Praxis Science III

1. Which two criteria are necessary and sufficient for something to be classified as matter?

It must occupy a fixed volume, and it must have mass.

It must take up space and it must have mass.

It must have no net electrical charge, and it must have weight.

It must take up space, and it must have weight.

The first answer choice is not correct because a gas is matter, but does not occupy a fixed volume. The third answer choice is not true because ions are matter, have net electrical charges, and matter that is not in the range of a gravitational force, does not have weight. The fourth choice is not correct because matter that is not in the range of a gravitational force does not have weight. The second answer choice therefore, is the correct answer.

Explanation

The first answer choice is not correct because a gas is matter, but does not occupy a fixed volume. The third answer choice is not true because ions are matter, have net electrical charges, and matter that is not in the range of a gravitational force, does not have weight. The fourth choice is not correct because matter that is not in the range of a gravitational force does not have weight. The second answer choice therefore, is the correct answer.

2. What does the symbol above mean in organic chemistry?

Not equal to.

Stoichiometrically equivalent to.

Triple bond.

Three anions.

The symbol stands for triple bond, which is usually a bond between two carbon atoms.

Explanation

The symbol stands for triple bond, which is usually a bond between two carbon atoms.

3. While cloud gazing, Bobby tells Susan that he can name three different types of clouds. If he was right, what were three types of clouds that Bobby named?

Nillostratus, cirrus, and cumulus.

Cumulus, stratus, and cirrus.

Nibostratus, columbus, and nimbus.

Cumbonimbulus, stratus and curious.

The three basic types of clouds are cumulus, stratus and cirrus. There are other more complex cloud types, but these are the three main types.

Explanation

The three basic types of clouds are cumulus, stratus and cirrus. There are other more complex cloud types, but these are the three main types.

4. Harold is the only one in his class with red hair. He has the highest grade in the class. James concludes that red hair makes Harold smarter than everyone in his class. Which of the following describes the error that James has made?

Harold is also the only one with blue eyes, which is more likely to be causing his intelligence.

Sally also has red hair, but dyes it.

Harold’s brother is a "D" student, and also has red hair.

Just because red hair and intelligence occur in the same person, does not mean that red hair causes intelligence.

A common mistake in science is to assume a causal link between things, when there is only an association. In the sample case, red hair is associated with good school performance. Much stronger evidence would be to administer a test of intelligence to a large group of people with red hair, and to a large group of people without red hair. If most people with red hair did significantly better than people without red hair, then it may be concluded that people with red hair do better on certain tests than those without red hair.

Explanation

A common mistake in science is to assume a causal link between things, when there is only an association. In the sample case, red hair is associated with good school performance. Much stronger evidence would be to administer a test of intelligence to a large group of people with red hair, and to a large group of people without red hair. If most people with red hair did significantly better than people without red hair, then it may be concluded that people with red hair do better on certain tests than those without red hair.

5. The earth's atmosphere consists of three major gases . Which is the most abundant gas?

Carbon dioxide.

Oxygen.

Nitrogen.

Argon.

Approximately 78 % of the earth's atmosphere is composed of nitrogen.

Explanation

Approximately 78 % of the earth's atmosphere is composed of nitrogen.

6. By chemical testing, you have determined that an unknown chemical is either barium chloride or sodium chloride. Trying to make the final elimination, another student asks. Why don't you just taste the two chemicals and the one that tastes salty will be sodium chloride or salt? What do you think of that idea?

It is a great idea for making the final determination.

It probably will not work.

It makes a lot of sense from a scientific standpoint.

It violates lab safety protocols.

Never taste or eat anything in a lab. It is a violation of the safety rules. Small amounts of sodium chloride are non-toxic, but barium chloride could be toxic.

Explanation

Never taste or eat anything in a lab. It is a violation of the safety rules. Small amounts of sodium chloride are non-toxic, but barium chloride could be toxic.

7. When the relative humidity of the air is high, which of the following does it mean?

The air is holding one-half (1/2) of the amount of water that it can hold.

Relative humidity refers to a measurement of how much water air can hold at a certain temperature. A high humidity indicates a high water content.

Explanation

Relative humidity refers to a measurement of how much water air can hold at a certain temperature. A high humidity indicates a high water content.

8. Out of the following list, which option is the most powerful way of conserving the Earth's resources and saving energy?

Cloning.

Recycling.

Using nanotechnology.

Logging.

Recycling is a powerful way of saving the Earth's resources and reducing overall energy consumption.

Explanation

Recycling is a powerful way of saving the Earth's resources and reducing overall energy consumption.

9. Kepler's First Law states which of the following?

That the orbit of every planet is a circle with the sun at its center.

That the orbit of any planet can be an ellipse if it is also influenced by another large heavenly body.

That the orbit of every planet is an ellipse with the sun at a focus.

That the radius of orbit of every planet decreases with every rotation, and that its time period correspondingly increases.

Kepler's First Law states that the orbit of every planet is an ellipse with the sun at a focus. If the two centers of the ellipse are close to each other, the orbit has a low eccentricity and appears almost circular, which is the case for many planets. But the elliptical nature of orbiting bodies can explain the orbits of all bodies around the sun.

Explanation

Kepler's First Law states that the orbit of every planet is an ellipse with the sun at a focus. If the two centers of the ellipse are close to each other, the orbit has a low eccentricity and appears almost circular, which is the case for many planets. But the elliptical nature of orbiting bodies can explain the orbits of all bodies around the sun.

10. A thirsty chemist accidentally makes some ice water from normal ice cubes and ice cubes using water containing deuterium instead of hydrogen. How can he simply determine which of the ice cubes are made of D2O before he takes a drink?

The D2O cubes float higher than H2O

The D2O cubes sink to the bottom.

The D2O cubes are radioactive

The D2O cubes will not be cubes because they have a different crystal structure

Deuterium is hydrogen with an extra neutron. It is not radioactive (tritium is). When deuterium is made into water, it is quite similar to water chemically but has different physical properties. Deuterated water is often called heavy water because of the neutron. In a glass of water, D2O cubes would sink to the bottom because of their density.

Explanation

Deuterium is hydrogen with an extra neutron. It is not radioactive (tritium is). When deuterium is made into water, it is quite similar to water chemically but has different physical properties. Deuterated water is often called heavy water because of the neutron. In a glass of water, D2O cubes would sink to the bottom because of their density.

11. The increase of CO2 in the atmosphere is mainly the result of which of the following?

Methane production by some bacteria.

The burning of fossil fuels and wood.

Respiration products from the human population.

The absorption of infrared radiation escaping from the Earth.

The CO2 concentration in the atmosphere has increased approximately twenty-five percent (25%) in the last 150 years with the increased burning of fossil fuels.

Explanation

The CO2 concentration in the atmosphere has increased approximately twenty-five percent (25%) in the last 150 years with the increased burning of fossil fuels.

12. Places at mid latitudes have distinct seasons.Why is it hotter in the summer and colder in the winter in the Northern Hemisphere?

The Earth is farther away from the sun in its orbit during the winter months than during the summer months.

The sun gives out more heat during the summer months.

Sea and air currents shift the temperature between summer and winter months.

Because of the axial tilt, the Northern Hemisphere is pointed towards the Sun for part of the year (summer) and away from the Sun for part of the year (winter). When a hemisphere is pointed towards the Sun, sunlight hits the ground at a more vertical angle and gives more energy per unit of area on the surface, resulting in warmer temperatures.

Explanation

Because of the axial tilt, the Northern Hemisphere is pointed towards the Sun for part of the year (summer) and away from the Sun for part of the year (winter). When a hemisphere is pointed towards the Sun, sunlight hits the ground at a more vertical angle and gives more energy per unit of area on the surface, resulting in warmer temperatures.

13. What evidence does not support the Plate Tectonic Theory?

Seismic activity.

Uplifted mountain regions.

Catastrophism.

Volcanic activity along subduction zones.

The Theory of Catastrophism is the idea that the Earth has been subjected to sudden, short-lived, violent events in the past, possibly worldwide in scope. Those events do not have a connection to the gradual change brought about by the Plate Tectonic Theory.

Explanation

The Theory of Catastrophism is the idea that the Earth has been subjected to sudden, short-lived, violent events in the past, possibly worldwide in scope. Those events do not have a connection to the gradual change brought about by the Plate Tectonic Theory.

14. Which of the following laws of thermodynamics is an expression of the principle of conservation of energy?

First law of thermodynamics

Second law of thermodynamics

Third law of thermodynamics

Zeroth law of thermodynamics

The first law of thermodynamics, an expression of the principle of conservation of energy, states that energy can be transformed (changed from one form to another), but it can neither be created nor destroyed. Alternatively, the increase in the internal energy of a system is equal to the amount of energy added by heating the system, minus the amount lost as a result of the work done by the system on its surroundings.

Explanation

The first law of thermodynamics, an expression of the principle of conservation of energy, states that energy can be transformed (changed from one form to another), but it can neither be created nor destroyed. Alternatively, the increase in the internal energy of a system is equal to the amount of energy added by heating the system, minus the amount lost as a result of the work done by the system on its surroundings.

15. There used to be nine planets until Pluto was downgraded to a dwarf planet. Which of the following lists includes the eight remaining planets in their order from the sun?

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Neptune, and Uranus.

Mercury, Venus, Mars, Earth, Jupiter, Saturn, Neptune, and Uranus.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Mercury, Mars, Earth, Venus, Jupiter, Saturn, Neptune, and Uranus.

The correct order of the eight remaining planets is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Explanation

The correct order of the eight remaining planets is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

16. What does the graph illustrate best?

Radioactive decay.

A biological population at punctuated equilibrium.

How the brightness of a star diminishes with distance.

The drastic collapse of a population.

The graph best illustrates the punctuated equilibrium of a population as it fluctuates over time. That may be in response to a predator or a seasonal cycle.

Explanation

The graph best illustrates the punctuated equilibrium of a population as it fluctuates over time. That may be in response to a predator or a seasonal cycle.

17. In scientific inquiry, an attitude of reserved doubt or suspended judgment toward information until all the evidence is carefully examined is called which of the following?

Positivism.

Relativism.

Skepticism.

The philosophy of Plato's Cave.

Skepticism in science means to reserve judgment until all the evidence is carefully examined.
That can be a positive attribute in the investigation of difficult ideas.

Explanation

Skepticism in science means to reserve judgment until all the evidence is carefully examined.
That can be a positive attribute in the investigation of difficult ideas.

18. Which is the largest ocean on earth?

The Atlantic.

The Pacific.

The Indian.

The Arctic.

The world's oceans in order of size, beginning with the largest, are: Pacific, Atlantic, Indian, Southern and Arctic oceans. The Pacific is about twice the size as the Atlantic Ocean.

Explanation

The world's oceans in order of size, beginning with the largest, are: Pacific, Atlantic, Indian, Southern and Arctic oceans. The Pacific is about twice the size as the Atlantic Ocean.

19. What are the elements with complete electron shell configurations called?

Noble gases.

Alkali metals.

Halogens.

Chalcogens.

Noble gases are in Group 18 with complete electron shells. The term, noble gas was coined since they do not react with other substances under normal circumstances because of their full electron shells.

Explanation

Noble gases are in Group 18 with complete electron shells. The term, noble gas was coined since they do not react with other substances under normal circumstances because of their full electron shells.

20. Science classes sometimes promote the idea that all meaningful questions have quantitative right answers and that open-ended questions do not merit attention. What best illustrates that contention to be inaccurate?

The popular media.

The history of science and technology.

Current science course work and curriculum.

Nobel prize winners.

Any course in the history of science or technology can provide a great remedy to this belief. Science history shows that opened-ended questions, uncertainty, serendipity, and many different paths have lead to good science.

Explanation

Any course in the history of science or technology can provide a great remedy to this belief. Science history shows that opened-ended questions, uncertainty, serendipity, and many different paths have lead to good science.

21. Many claims concerning what science can and cannot do are made in the media today. Some claims are science fiction while others might be true one day. How is it possible to tell whether it is possible to clone a dinosaur from DNA in amber? I Look at the level of technical difficulty of the problem. II Seek expert judgments. III Become knowledgable of the technology that exists and is under development.

I only.

I and II only.

II and III only.

I, II, and III.

All of the above criteria will help determine that a Jurassic Park dinosaur cloned from DNA trapped in amber is very improbable. The technical complexity of such a task is enormous, and any expert will confirm that.

Explanation

All of the above criteria will help determine that a Jurassic Park dinosaur cloned from DNA trapped in amber is very improbable. The technical complexity of such a task is enormous, and any expert will confirm that.

22. Identify the specific element that corresponds to the following electron configuration. [Kr] 5s2 4d10 5p4

Bromine

Tellurium

Antimony

Strontium

Electrons 5s2 represent the fifth row on the Periodic Table and the second Column, Electrons 4d10 represent the ten elements in the middle of the Periodic Table (Transition Metals), and the 5p4 is the fifth row and Column 16, Tellurium.

Explanation

Electrons 5s2 represent the fifth row on the Periodic Table and the second Column, Electrons 4d10 represent the ten elements in the middle of the Periodic Table (Transition Metals), and the 5p4 is the fifth row and Column 16, Tellurium.

23. Under which of the following circumstance(s) is a teacher specifically and legally liable?

When a student sticks himself with a needle.

When a teacher leaves the classroom unattended, and an injury occurs.

When a student sneaks a snack into the classroom or laboratory during a biological experiment.

All of the above.

In the course of a day, whether involved in science or not, accidents can happen, and teachers cannot be held responsible. However, a teacher or administrator must be present at all times during an experiment. If the teacher leaves and an accident occurs, the teacher can be held legally accountable and liable.

Explanation

In the course of a day, whether involved in science or not, accidents can happen, and teachers cannot be held responsible. However, a teacher or administrator must be present at all times during an experiment. If the teacher leaves and an accident occurs, the teacher can be held legally accountable and liable.

24. A total of 800 joules of energy is added to ten (10) grams of a liquid, causing it to increase in temperature from 23oC to 63oC. What is the heat capacity of the liquid?

2 J/g oC.

4.18 J/g oC.

20 J/g oC.

80 J/g oC.

The equation, q = mCpDT can be solved for Cp to give: Cp = q/ mDT = 800/(10)(40) = 2 J/g oC.

Explanation

The equation, q = mCpDT can be solved for Cp to give: Cp = q/ mDT = 800/(10)(40) = 2 J/g oC.

25. In a safe lab, electricity and which of the following do not mix?

Open flames.

Water.

Chemicals.

Culture plates.

Electricity and water present a shock hazard. In a safe lab, water should be kept away from all electrical equipment.

Explanation

Electricity and water present a shock hazard. In a safe lab, water should be kept away from all electrical equipment.

26. In a debate, an opponent of organic farming argues that organic food is considered no more nutritious than food that is regularly grown. Which of the following might be an environmental and health-related argument that a pro-organic debator might make in response?

Pesticides used in conventional food affect other living organisms.

Organic food tastes better than conventional food.

Organic food is more visually attractive than conventional food.

Organic produce is easier to grow than conventional produce.

All of the above might be used in a debate about the merits of organic farming. However, only the argument about pesticides deals mainly with environmental and health concerns, as the question asks.

Explanation

All of the above might be used in a debate about the merits of organic farming. However, only the argument about pesticides deals mainly with environmental and health concerns, as the question asks.

27. The failure of a lens to focus all colors to the same point is called which of the following?

A spherical aberration.

A chromatic aberration.

A field curvature.

A tilt.

Chromatic aberration (also called achromatism) refers to the failure of a lens to focus all colors to the same point, and occurs because lenses have a different refractive index for different wavelengths of light (the dispersion of the lens). The refractive index decreases with increasing wavelength.

Explanation

Chromatic aberration (also called achromatism) refers to the failure of a lens to focus all colors to the same point, and occurs because lenses have a different refractive index for different wavelengths of light (the dispersion of the lens). The refractive index decreases with increasing wavelength.

28. From the above graph of heat applied versus temperature what approximately is the temperature of vaporization of zinc?

700 K

800 K

1200 K

1500 K

The graph shows the heat applied on the y-axis and the temperature on the x-axis. There are 2 discontinuities in the graph. One is close to 700 K and the other at approximately 1200 K. These discontinuities arise as at the point near 700 K zinc melts and changes state from solid to liquid and at around 1200 K zinc changes state from liquid to vapor. When the metal changes to vapor a lot of heat also called the heat of vaporization is required for the state change. This is the reason for the temperature remaining constant even when extra heat is applied. As the metal first melts and then vaporizes, the second discontinuity around 1200 K is the temperature of vaporization.

Explanation

The graph shows the heat applied on the y-axis and the temperature on the x-axis. There are 2 discontinuities in the graph. One is close to 700 K and the other at approximately 1200 K. These discontinuities arise as at the point near 700 K zinc melts and changes state from solid to liquid and at around 1200 K zinc changes state from liquid to vapor. When the metal changes to vapor a lot of heat also called the heat of vaporization is required for the state change. This is the reason for the temperature remaining constant even when extra heat is applied. As the metal first melts and then vaporizes, the second discontinuity around 1200 K is the temperature of vaporization.

29. Who is credited with the discovery of the double helix structure of DNA?

Linus Pauling.

Charles Darwin.

Jonas Salk.

James Watson and Francis Crick.

Watson and Crick are credited with the description of DNA as a double helix from their paper in the journal Nature in 1953. Watson, Crick and another researcher named Maurice Wilkins won the Nobel Prize in Medicine for that work. There is some controversy surrounding this achievement, since an X-ray crystallographer named Rosalind Franklin may have provided the critical information for that discovery, yet she was overlooked for the Prize, and in many historical accounts of the discovery.

Explanation

Watson and Crick are credited with the description of DNA as a double helix from their paper in the journal Nature in 1953. Watson, Crick and another researcher named Maurice Wilkins won the Nobel Prize in Medicine for that work. There is some controversy surrounding this achievement, since an X-ray crystallographer named Rosalind Franklin may have provided the critical information for that discovery, yet she was overlooked for the Prize, and in many historical accounts of the discovery.

30. A scientist carefully isolates a nerve cell from a rat, and places it in a dish filled with liquid. Over a matter of minutes, the cell appears to get bigger even though he has not changed the optics. Which of the following is the most likely explanation for that occurrence?

The liquid solution is hypotonic relative to the nerve cell.

The liquid solution is hypertonic relative to the nerve cell.

An electrical current has been applied to the nerve cell.

The nerve cell has detached from the bottom of the dish, and is floating.

The buffer solution that the scientist is using is apparently hypotonic relative to the nerve cell. In order to reach equilibrium, water has entered the nerve cell, an area of relatively high solute concentration. The way to experimentally avoid that, is to prepare a buffer that is the same osmolarity with that of the inside of the nerve cell. An electrical current does not change the size of a nerve cell to a detectable degree. Incidentally, if the nerve cell has detached, it will most likely appear to be out of focus, rather than simply larger.

Explanation

The buffer solution that the scientist is using is apparently hypotonic relative to the nerve cell. In order to reach equilibrium, water has entered the nerve cell, an area of relatively high solute concentration. The way to experimentally avoid that, is to prepare a buffer that is the same osmolarity with that of the inside of the nerve cell. An electrical current does not change the size of a nerve cell to a detectable degree. Incidentally, if the nerve cell has detached, it will most likely appear to be out of focus, rather than simply larger.

31. Approximately how many days are there in an Earth year?

356.

365.

356.25.

365.25.

The accurate number is 365.2425, meaning solar days. That is why there is a Leap Year with a day added every four years.

Explanation

The accurate number is 365.2425, meaning solar days. That is why there is a Leap Year with a day added every four years.

32. What type of terrestrial biome supports the growth of large, deciduous trees?

Desert.

Temperate forest.

Taiga.

Tundra.

Temperate forests grow in mid-latitude regions where there is sufficient moisture to support the growth of large, broad-leaf deciduous trees, such as in the Eastern region of the United States, most of Central Europe, and part of Eastern Asia.

Explanation

Temperate forests grow in mid-latitude regions where there is sufficient moisture to support the growth of large, broad-leaf deciduous trees, such as in the Eastern region of the United States, most of Central Europe, and part of Eastern Asia.

33. Given an unknown liquid, Bethany wants to design an experiment that will determine whether the solution is ionic or not. Which one of the following tests will be most helpful to her?

Probe the liquid with a conductivity meter.

Heat the liquid to determine its boiling point.

Cool the liquid and determine its freezing point.

Probe the liquid with an oxygen level meter.

Ionic solutions always conduct electricity well, so the best test will be a conductivity test.
If the solution has a high conductivity rate, then it is an ionic solution.

Explanation

Ionic solutions always conduct electricity well, so the best test will be a conductivity test.
If the solution has a high conductivity rate, then it is an ionic solution.

34. Convert a temperature of 100 oC to absolute temperature in oK, to the nearest whole number.

373oK.

212oK.

459oK.

180oK.

Conversion from degrees Centigrade to degrees Kelvin is accomplished by adding 273.15 (273 to the nearest whole number). The second answer is the equivalent temperature in degrees Fahrenheit. The third answer is the number that should be added to a temperature in degrees Fahrenheit to convert to degrees Rankine. The fourth answer is an intermediate number in the conversion of 100oC to oF.

Explanation

Conversion from degrees Centigrade to degrees Kelvin is accomplished by adding 273.15 (273 to the nearest whole number). The second answer is the equivalent temperature in degrees Fahrenheit. The third answer is the number that should be added to a temperature in degrees Fahrenheit to convert to degrees Rankine. The fourth answer is an intermediate number in the conversion of 100oC to oF.

35. What is a very important consideration when considering the ethics of pre-natal testing?

Will it be used to unnecessarily end a life?

Is it economically feasible?

Is it technically feasible?

Is it practical?

Tough choices, but any consideration that involves ending a life should be carefully considered. Would it be ethical to end the life of a boy before he is born because you already have three boys ?

Explanation

Tough choices, but any consideration that involves ending a life should be carefully considered. Would it be ethical to end the life of a boy before he is born because you already have three boys ?

36. Why are astronauts able to walk on the moon?

Because they use jet propulsion.

Because they wear magnetic shoes.

Because the cohesion between their shoes and the moon is dust.

Because of slight gravity on the moon.

The moon actually has a slight gravity that is approximately one-sixth (1/6) that of the Earth's. The astronauts are able to carry much more weight, jump higher, and hit golf balls farther because of the slight lunar gravity.

Explanation

The moon actually has a slight gravity that is approximately one-sixth (1/6) that of the Earth's. The astronauts are able to carry much more weight, jump higher, and hit golf balls farther because of the slight lunar gravity.

37. Why is using simple solar distillers a more elegant solution than a more high tech solution for addressing Third World water quality problems?

Solar distillers are easy to use.

Third World countries cannot afford or support high tech solutions.

High tech solutions are too complicated to use.

Other solutions are implemented too slowly.

Sustainable answers to local problems are more likely if they are affordable and can be supported by local technological skills. The solar still is inexpensive, easy to use, does not require electricity, and can easily be supported by the technological skills of a Third World country.

Explanation

Sustainable answers to local problems are more likely if they are affordable and can be supported by local technological skills. The solar still is inexpensive, easy to use, does not require electricity, and can easily be supported by the technological skills of a Third World country.

38. As a project, students will be studying the effect of light on the algae growth. Which of the following is the independent variable?

The salt content of the water.

The color of the algae.

The intensity of the light.

The size of the algae.

The independent variable is the variable that is being tested in an experiment. The dependent variable is what is being measured. Ideally, all other variables should be controlled, or made the same in both groups. The intensity of light could be altered by using various filters on a lamp, and would be the independent variable. The algae size might be the dependant variable, and other factors like the water content and the algae color used for the experiment could be controlled.

Explanation

The independent variable is the variable that is being tested in an experiment. The dependent variable is what is being measured. Ideally, all other variables should be controlled, or made the same in both groups. The intensity of light could be altered by using various filters on a lamp, and would be the independent variable. The algae size might be the dependant variable, and other factors like the water content and the algae color used for the experiment could be controlled.

39. The unit of measurement of the optical power of a lens is which of the following?

Diopter.

Meter.

Radians.

Degree.

A diopter, (or dioptre), is a unit of measurement of the optical power of a lens or curved mirror. It is equal to the reciprocal of the focal length measured in meters (that is, 1/meter). For example, a 3 diopter lens brings parallel rays of light to focus at 1/3 meter.

Explanation

A diopter, (or dioptre), is a unit of measurement of the optical power of a lens or curved mirror. It is equal to the reciprocal of the focal length measured in meters (that is, 1/meter). For example, a 3 diopter lens brings parallel rays of light to focus at 1/3 meter.

40. The coefficient of thermal conductivity of a metallic rod depends on

Length of the rod

Nature of the metal

Cross-sectional area of the rod

The temperature difference between the ends of the rods

The coefficient of thermal conductivity depends only on the nature of the metal. The other options including length of the rod, cross-sectional area of the rod and temperature difference between the two ends only affects the amount of heat that is being transferred from one end to the other.

Explanation

The coefficient of thermal conductivity depends only on the nature of the metal. The other options including length of the rod, cross-sectional area of the rod and temperature difference between the two ends only affects the amount of heat that is being transferred from one end to the other.

41. Which is the correct name of the compound K2S?

Potassium sulfate.

Potassium sulfur.

Potassiate sulfur.

Potassium sulfide.

Sulfur has a charge of negative 2 and as a monoatomic ion, that indicates that the suffix -ide should be used. Potassium has a charge of positive 1, which means that it retains the name potassium. The two coming together creates a neutral molecule, so both retain those names and the correct form is potassium sulfide.

Explanation

Sulfur has a charge of negative 2 and as a monoatomic ion, that indicates that the suffix -ide should be used. Potassium has a charge of positive 1, which means that it retains the name potassium. The two coming together creates a neutral molecule, so both retain those names and the correct form is potassium sulfide.

42. Cody was trying to show that the mountain pine beetle populations were higher after a year with a mild winter. What would be the best data collection method for his study?

Mountain pine beetle populations by state for the year 2008 with the average temperature of each state.

Average Montana mountain pine beetle populations for the years 1995 to 1999 with the coldest recorded temperature for those years.

More years of data with more specific average temperatures would make the Colorado data better. Data for only one year, the lowest temperature, or projected temperatures would be of lesser value.

Explanation

More years of data with more specific average temperatures would make the Colorado data better. Data for only one year, the lowest temperature, or projected temperatures would be of lesser value.

43. Which water cycle phase is represented in the graphic?

Transpiration.

Precipitation.

Evaporation.

Condensation.

The water cycle phase represented in the graphic is the one in which water vapor is condensed into the clouds. It takes place after evaporation and before precipitation.

Explanation

The water cycle phase represented in the graphic is the one in which water vapor is condensed into the clouds. It takes place after evaporation and before precipitation.

44. Human blood pH is closest to which of the following values?

6.8.

7.0.

7.1.

7.4.

The lungs and the kidney are constantly adjusting to keep the pH of blood close to 7.4. The lungs can increase or decrease respiration rate to increase or decrease pH, respectively. The kidneys can absorb, secrete, or excrete various compounds to keep blood pH within a narrow range.

Explanation

The lungs and the kidney are constantly adjusting to keep the pH of blood close to 7.4. The lungs can increase or decrease respiration rate to increase or decrease pH, respectively. The kidneys can absorb, secrete, or excrete various compounds to keep blood pH within a narrow range.

45. Which of the following is true of the primary growth of a tree?

It occurs through the activity of the vascular cambium.

It occurs through the activity of the root cap.

It occurs only in the first year of the life of the tree.

It occurs through the activity of the apical meristem.

The apical meristem consists of a small mound of rapidly dividing cells. The cells just below the shoot apical meristem elongate and then mature into differentiated cells of the primary plant stem (or tree trunk in this case). The growth period in cells of the shoot (in both length and diameter) may last longer than the growth period in the root; so growth in the shoot can be detected quite a distance behind the growing tip of the apical meristem.

Explanation

The apical meristem consists of a small mound of rapidly dividing cells. The cells just below the shoot apical meristem elongate and then mature into differentiated cells of the primary plant stem (or tree trunk in this case). The growth period in cells of the shoot (in both length and diameter) may last longer than the growth period in the root; so growth in the shoot can be detected quite a distance behind the growing tip of the apical meristem.

46. Theoretically, the absolute lowest temperature is

-273 K

-273.15 °F

0 K

273 K

Absolute zero which is 0 K or -273.15 °C or -459.68 °F is the temperature when there is no more energy able to be removed. This is the point on the thermodynamic (absolute) temperature scale where all kinetic motion in the particles comprising matter ceases and they are at complete rest in the “classic” (non-quantum mechanical) sense. The Kelvin scale, which a scale of thermodynamic temperature, sets its zero point at absolute zero.

Explanation

Absolute zero which is 0 K or -273.15 °C or -459.68 °F is the temperature when there is no more energy able to be removed. This is the point on the thermodynamic (absolute) temperature scale where all kinetic motion in the particles comprising matter ceases and they are at complete rest in the “classic” (non-quantum mechanical) sense. The Kelvin scale, which a scale of thermodynamic temperature, sets its zero point at absolute zero.

47. The meteorological effect of a coastline with high mountains will cause which of the following?

Higher winds.

Higher precipitation.

Lower winds.

Lower precipitation.

High mountains in a coastal region will usually cause greater precipitation and heavy, water-ladened clouds must dump some of their water to be able to pass. That is true on the West coasts of both North and South America.

Explanation

High mountains in a coastal region will usually cause greater precipitation and heavy, water-ladened clouds must dump some of their water to be able to pass. That is true on the West coasts of both North and South America.

48. When it is below freezing, rain turns into snow. About how many inches of snow are there in one inch of rain?

Average ten (10) inches of snow to one (1) inch of rain.

Average one (1) inch of snow to ten (10) inches of rain.

They are about equal.

Snow to liquid equivalents can vary immensely.

The average equivalent is ten (10) inches of snow being the same as one (1) inch of rain. That varies slightly, depending on how wet the snow is.

Explanation

The average equivalent is ten (10) inches of snow being the same as one (1) inch of rain. That varies slightly, depending on how wet the snow is.

49. What is oxidation number of sulfur in H2SO4?

-2

+2

+6

-6

The sum of the charge numbers must equal zero in a compound. Oxygen is -8,
Hydrogen is +2, therefore, Sulfur is +6

Explanation

The sum of the charge numbers must equal zero in a compound. Oxygen is -8,
Hydrogen is +2, therefore, Sulfur is +6

50. What name is given to the molecule that should technically be known as dihydrogen dioxide?

Hydrogen peroxide.

Water.

Ammonia.

Hydrogen sulfide.

The name, dihydrogen dioxide indicates that the molecule has two molecules of hydrogen and two of oxygen, thereby given the chemical symbol, H2O2. That is the chemical symbol for hydrogen peroxide. Water is H2O; ammonia is NH3; and hydrogen sulfide is H2S.

Explanation

The name, dihydrogen dioxide indicates that the molecule has two molecules of hydrogen and two of oxygen, thereby given the chemical symbol, H2O2. That is the chemical symbol for hydrogen peroxide. Water is H2O; ammonia is NH3; and hydrogen sulfide is H2S.

51. Kelly observed strange beads of dirt with small holes next to them on his front lawn after every rain. What kind of scientific investigation could he conduct to find out what formed those holes and beads?

Research the problem on the Internet.

Carefully observe the lawn for a long, continuous period after a rain.

Ask everyone he knows how they think the beads were formed.

Go to the libray and look for books on lawn maintenance.

Carefully observing the lawn would be the most scientific way to answer his question. All the other methods involve research only.

Explanation

Carefully observing the lawn would be the most scientific way to answer his question. All the other methods involve research only.

52. The relative density of ice is 0.9 and that of sea-water is 1.125. What fraction of the whole volume of an iceberg appears above the surface of the sea?

One-fifth (1/5).

Two-fifths (2/5).

Three-fifths (3/5).

Four-fifths (4/5).

Density of ice is 900 kgm-3. Density of sea water is 1125 kgm-3. If V is the total volume of the iceberg and n is the fraction of the volume of the iceberg that appears above the surface of sea water, then the volume of the submerged part of the iceberg is (1-n)V. From the Principle of Flotation, we have (1-n)Vx1125xg=900Vxg. 1-n=900/1125, n=0.2=1/5.

Explanation

Density of ice is 900 kgm-3. Density of sea water is 1125 kgm-3. If V is the total volume of the iceberg and n is the fraction of the volume of the iceberg that appears above the surface of sea water, then the volume of the submerged part of the iceberg is (1-n)V. From the Principle of Flotation, we have (1-n)Vx1125xg=900Vxg. 1-n=900/1125, n=0.2=1/5.

53. Why are eukaryotic cells within an organism different? For example, skin cells are different from neurons.

They contain different DNA

They contain different genes

Each has chromosomes unique to the cell

Different genes are expressed in each cell type

The entire genome is present in every cell formed by mitosis in the body. Obviously the genes and DNA must be the same. Therefore, what make cells different from one another is the genes that are expressed in each cell. Even though all the genes for a skin cell are present in nerve cells and vice versa, many of the genes that are expressed in a nerve cell are different from a skin cell.

Explanation

The entire genome is present in every cell formed by mitosis in the body. Obviously the genes and DNA must be the same. Therefore, what make cells different from one another is the genes that are expressed in each cell. Even though all the genes for a skin cell are present in nerve cells and vice versa, many of the genes that are expressed in a nerve cell are different from a skin cell.

54. Which of the following configurations of resistors has the least total resistance? (All the resistors used are of 1 ohm)

A

B

C

D

Looking at the configuration A, the resistors are in series has a total resistance of 1+1+1=3 ohm. In configuration B the 2 in parallel form a resistor of ½ ohm which in series with a 1 ohm resistor gives the total resistance as 1.5 ohm. In configuration C the three resistors are in parallel and give a resistance of 1/3 ohm. In configuration D one of the resistances is shorted and hence the configuration reduces to two resistances in parallel giving a total Resistance of 1/2 ohm. Therefore, the configuration C has the least resistance.

Here remember that for resistances in series: Req=R1+R2+R3+....Rn , for resistances in parallel: Req-1=R1-1+R2-1+R3-1+....Rn-1.

Explanation

Looking at the configuration A, the resistors are in series has a total resistance of 1+1+1=3 ohm. In configuration B the 2 in parallel form a resistor of ½ ohm which in series with a 1 ohm resistor gives the total resistance as 1.5 ohm. In configuration C the three resistors are in parallel and give a resistance of 1/3 ohm. In configuration D one of the resistances is shorted and hence the configuration reduces to two resistances in parallel giving a total Resistance of 1/2 ohm. Therefore, the configuration C has the least resistance.

Here remember that for resistances in series: Req=R1+R2+R3+....Rn , for resistances in parallel: Req-1=R1-1+R2-1+R3-1+....Rn-1.

55. Which disease might have the potential to cause society the most harm?

Marlburg Virus.

The seasonal flu virus.

Leprosy bacteria.

A new variant of swine flu.

The most threatening danger lies in a pandemic of a new swine flu variant. The last time that it occurred, over 20 million people were estimated to have died.

Explanation

The most threatening danger lies in a pandemic of a new swine flu variant. The last time that it occurred, over 20 million people were estimated to have died.

56. What is DNA wrapped around in a nucleosome?

Ribosome

Ligase

Histone

Helicase

One of the reasons that such an enormous molecule of DNA can form a chromosome is because of the existence of histones. Histones are small proteins, mostly form alpha helices, which acts as a spool of sorts for DNA. They also promote unwinding for DNA translation and replication.

Explanation

One of the reasons that such an enormous molecule of DNA can form a chromosome is because of the existence of histones. Histones are small proteins, mostly form alpha helices, which acts as a spool of sorts for DNA. They also promote unwinding for DNA translation and replication.

57. Choose the correct option. In planetary motion

The speed along the orbit remains the same

The angular speed remains constant

The total angular momentum remains constant

The radius of the orbit remains constant

The orbits of planets are elliptical. The speed of the planet and its angular speed or angular frequency keeps changing. Since no net torque acts on the planet, its angular momemtum remains constant.

Explanation

The orbits of planets are elliptical. The speed of the planet and its angular speed or angular frequency keeps changing. Since no net torque acts on the planet, its angular momemtum remains constant.

58. What is apparently wrong with the data below? 1 2 3 4 5 1 4 9 14 25

The value 25 should be 15 based on the other numbers.

It is linear.

The value 14 should be 16 based on the other numbers.

There are not enough numbers collected.

This data set appears to show a series of pairs in which the second member is equal to the square of the first: (1,1)( 2,4)(3,9) and (5,25); but (4,14) does not follow the pattern. The pattern should be (4,16) .

Explanation

This data set appears to show a series of pairs in which the second member is equal to the square of the first: (1,1)( 2,4)(3,9) and (5,25); but (4,14) does not follow the pattern. The pattern should be (4,16) .

59. Every day an average of two people are born for every one that dies, leaving a ratio of 2 to 1 for births to deaths. What would happen to this ratio if the average life expectancy were to double?

It would go to 4 to 1.

It would go to 1 to 1.

It would not change.

It would go to 1 to 4.

Doubling life expectancy would lower the death rate by about one-half. This would change the ratio to two (2) to 0.5, or four (4) births to one (1) death.

Explanation

Doubling life expectancy would lower the death rate by about one-half. This would change the ratio to two (2) to 0.5, or four (4) births to one (1) death.

60. Based on the drawing above, what season in the Northern Hemisphere is being illustrated?

Winter.

Spring.

Summer.

Fall.

The Earth has a 23° tilt either away from the Northern Hemisphere in the winter, or toward the Northern Hemisphere in the summer. The illustration shows the winter tilt.

Explanation

The Earth has a 23° tilt either away from the Northern Hemisphere in the winter, or toward the Northern Hemisphere in the summer. The illustration shows the winter tilt.

61. Which of the following does not describe the forces of competition on species?

Competition between species occurs when both strive to obtain a limited resource.

Competition may result in the displacement of one of the species.

Competitors cannot exist together.

Competing species may reach an equilibrium in population size.

Competitors can exist together although one may be more adversely affected than the other. Anytime there is a limited resource-not enough for everyone-competition will develop. If one species is more successful at obtaining the limited resource, the other species may become extinct or be forced to relocate. If both species are equally successful at obtaining the limited resource, they should experience the same level of death rate and relocation.

Explanation

Competitors can exist together although one may be more adversely affected than the other. Anytime there is a limited resource-not enough for everyone-competition will develop. If one species is more successful at obtaining the limited resource, the other species may become extinct or be forced to relocate. If both species are equally successful at obtaining the limited resource, they should experience the same level of death rate and relocation.

62. On messenger RNA (mRNA), how many nucleotides are in each codon?

1

3

8

20

There are three nucleotides in each codon in mRNA. For example, when the ribosome comes to the three nucleotides Uracil-adenine-uracil (UAU), this codon is translated into the amino acid tyrosine. The ribosome moves down the mRNA three more nucleotides and then translates the next codon or stops when it reaches a stop codon such as UGA.

Explanation

There are three nucleotides in each codon in mRNA. For example, when the ribosome comes to the three nucleotides Uracil-adenine-uracil (UAU), this codon is translated into the amino acid tyrosine. The ribosome moves down the mRNA three more nucleotides and then translates the next codon or stops when it reaches a stop codon such as UGA.

63. The latent heat of fusion of water at 0oC is 334 J/g, and its latent heat of vaporization at the same temperature is 2501 J/g. What is the latent heat of sublimation of water at 0oC?

334 J/g.

2167 J/g.

2501 J/g.

2835 J/g.

The latent heat of sublimation of a substance at a given temperature is the sum of the latent heat of fusion and the latent heat of vaporization of that substance at that temperature. Thus, the latent heat of sublimation of water at 0oC must be 334 + 2501 J/g = 2835 J/g.

Explanation

The latent heat of sublimation of a substance at a given temperature is the sum of the latent heat of fusion and the latent heat of vaporization of that substance at that temperature. Thus, the latent heat of sublimation of water at 0oC must be 334 + 2501 J/g = 2835 J/g.

64. If the "reactant side" of a chemical reaction equation is: 2 NH3(g) + 3 N2O(g) → , then how many atoms of nitrogen must be present on the "product side" of the equation?

Five (5).

Six (6).

Seven (7).

Eight (8).

There must be the same number of atoms of any element on the reactant side and the product side of a chemical reaction equation. There are eight (8) atoms of nitrogen shown on the reactant side, so there must also be eight (8) atoms of nitrogen on the product side.

Explanation

There must be the same number of atoms of any element on the reactant side and the product side of a chemical reaction equation. There are eight (8) atoms of nitrogen shown on the reactant side, so there must also be eight (8) atoms of nitrogen on the product side.

65. What is one of the toughest ethical questions about using technology to extend human life?

Determining who should live and who should die.

Determining how this technology should be financed?

Determining how long we can extend life?

Determining what is and what isn't a good quality life?

All of these are tough ethical questions, but the toughest appears to be who should determine who dies and who lives. We cannot know how long lives can be extended. Money should not be an issue, and it is very hard to determine the quality of a life. But it is even harder to determine the fairest way to decide who should live and who should die.

Explanation

All of these are tough ethical questions, but the toughest appears to be who should determine who dies and who lives. We cannot know how long lives can be extended. Money should not be an issue, and it is very hard to determine the quality of a life. But it is even harder to determine the fairest way to decide who should live and who should die.

66. When white light is refracted in glass, which of the constituent colors is refracted the most?

Red.

Violet.

Blue.

Yellow.

The refractive index of glass is inversely proportional to the square of the wavelength of light. The wavelength of red light is the highest, and that of violet is the lowest. Violet-colored light therefore, is refracted the most.

Explanation

The refractive index of glass is inversely proportional to the square of the wavelength of light. The wavelength of red light is the highest, and that of violet is the lowest. Violet-colored light therefore, is refracted the most.

67. The equation for the dissociation of nitrous acid is: HNO2 = H+ + NO2 - . If a solution of nitrous acid which is 0.0026N has a pH of 3, what is Ka for nitrous acid?

2 x 10-4.

2 x 10-5.

4 x 10-4.

4 x 10-5.

In the sample case,
Ka = [H+][NO2 -] / [HNO2]. Also: [H+] = [NO2 -] = 10-pH = 10-3 = 0.001.
In addition: [HNO2] = normality - [H+] = 0.0026 - 0.0001 = 0.0025.
Substituting values: Ka = (10-3 )( 10-3 )/(0.0025) = (1 x 10-4 )/(0.25) = 4 x 10-4.

Explanation

In the sample case,
Ka = [H+][NO2 -] / [HNO2]. Also: [H+] = [NO2 -] = 10-pH = 10-3 = 0.001.
In addition: [HNO2] = normality - [H+] = 0.0026 - 0.0001 = 0.0025.
Substituting values: Ka = (10-3 )( 10-3 )/(0.0025) = (1 x 10-4 )/(0.25) = 4 x 10-4.

68. Which of the following refers to the genetic divergence of one or more populations from a single parent species inhabiting the same geographic region, to a degree such that those populations become different species?

Peripatric speciation.

Allopatric speciation.

Parapatric speciation.

Sympatric speciation.

Sympatric speciation is the only one of the four (4) modes of speciation in which one species is originally contained with the range of another.

Explanation

Sympatric speciation is the only one of the four (4) modes of speciation in which one species is originally contained with the range of another.

69. An observer moves toward a stationary sound source with a velocity that is one-tenth (1/10th) of the velocity of sound. The apparent increase in frequency is which of the following?

Zero.

Five percent (5%).

Ten percent (10%).

Zero point one percent (0.1%).

F'=F(1+u/v). In the question, the observer moves toward the stationary source at 1/10 the speed of sound u/v=1/10. Therefore F'=(11/10)F and the increase in frequency is (F'-F)/F=0.1=10%.

Explanation

F'=F(1+u/v). In the question, the observer moves toward the stationary source at 1/10 the speed of sound u/v=1/10. Therefore F'=(11/10)F and the increase in frequency is (F'-F)/F=0.1=10%.

70. Human cloning has the potential to provide organs for the sick, but also to create severely deformed beings. There are many ethical points that need to be considered. What do you think that the best course on human cloning should be?

Allow it in every case.

Restrict it in every case.

Restrict it with some degree of freedom.

Continue doing what we are doing now.

Totally unrestricted use or totally restricted use seem unwise. Doing what we are already doing is not working. It would seem that restriction with carefully considered exceptions is the best course of action. .

Explanation

Totally unrestricted use or totally restricted use seem unwise. Doing what we are already doing is not working. It would seem that restriction with carefully considered exceptions is the best course of action. .

71. Which of the following is true regarding the movement of sap from a sugar source to a sugar sink?

Occurs through the apoplast of sieve-tube members.

May translocate sugars from the breakdown of stored starch up to the leaves

Is primarily a passive process.

Results mainly from diffusion.

The sieve tubes of the phloem carry food and other solutes from a sugar source to a sugar sink. The source is a plant organ that produces sugar by photosynthesis or the breakdown of starch (leaves are usually the source), whereas a sugar sink is a plant organ that consumes or stores sugar (growing roots, shoot tips, and fruits are sugar sinks supplied by phloem). A storage plant organ, such as tubers or bulbs, can either be a source or a sink, depending on the season.

Explanation

The sieve tubes of the phloem carry food and other solutes from a sugar source to a sugar sink. The source is a plant organ that produces sugar by photosynthesis or the breakdown of starch (leaves are usually the source), whereas a sugar sink is a plant organ that consumes or stores sugar (growing roots, shoot tips, and fruits are sugar sinks supplied by phloem). A storage plant organ, such as tubers or bulbs, can either be a source or a sink, depending on the season.

72. Which of the following best defines a closed population?

A community capable of sustaining itself under prevailing conditions.

A population that remains constant without measurable change.

A community in which individuals compete for the same limited resources.

An interbreeding group in a population.

A closed population is one that remains constant without measurable change. A community capable of sustaining itself under prevailing conditions is a climax kind. A community in which individuals compete for the same limited resources is a competition. An interbreeding group in a population is a deme.

Explanation

A closed population is one that remains constant without measurable change. A community capable of sustaining itself under prevailing conditions is a climax kind. A community in which individuals compete for the same limited resources is a competition. An interbreeding group in a population is a deme.

73. The most common salt in the ocean is which of the following?

KCl.

MgCl.

NaCl.

CaCl.

Sodium Chloride (NaCl ), or common table salt, is the most common salt in the ocean. It makes up about three percent (3%) by weight of common sea water.

Explanation

Sodium Chloride (NaCl ), or common table salt, is the most common salt in the ocean. It makes up about three percent (3%) by weight of common sea water.

74. Normal fruit flies have red eyes, but a scientist notices that a male fly has white eyes. He breeds the male with white eyes to three females with red eyes. Their offspring are listed in the table above. What can be said about the inheritance of white eyes in fruit flies?

That they are X-linked recessive.

That they are Y-linked recessive.

That they are autosomal dominant.

That they are autosomal recessive.

That is a classic experiment conducted by a geneticist named Dr. Morgan. From an experiment similar to it, he theorizes that the gene responsible for white eyes in male fruit flies is on the X chromosome, and that it is recessive. The inheritance is still 3:1; yet only males are affected and only half of that group. When the recessive gene is present in females, the other X chromosome dominates, and red eyes prevail. However, when there is only one copy of the X chromosome in males, the recessive gene is expressed. The reason that only some males have the gene is based on the classic principle of Mendel's Law of Independent Assortment of Genes.

Explanation

That is a classic experiment conducted by a geneticist named Dr. Morgan. From an experiment similar to it, he theorizes that the gene responsible for white eyes in male fruit flies is on the X chromosome, and that it is recessive. The inheritance is still 3:1; yet only males are affected and only half of that group. When the recessive gene is present in females, the other X chromosome dominates, and red eyes prevail. However, when there is only one copy of the X chromosome in males, the recessive gene is expressed. The reason that only some males have the gene is based on the classic principle of Mendel's Law of Independent Assortment of Genes.

75. A +1 diopter lens with a +3 diopter lens would give which of the following?

+ 0.75 diopter lens.

+4 diopter lens.

+3 diopter lens.

+.33 diopter lens.

Stacking lenses combines their power. A +1 diopter lens combined with a +3 diopter lens forms a +4 diopter system. This is how spectacle lenses work, by combining with the eye lens to form a lens with the required power.

Explanation

Stacking lenses combines their power. A +1 diopter lens combined with a +3 diopter lens forms a +4 diopter system. This is how spectacle lenses work, by combining with the eye lens to form a lens with the required power.

76. If you react 0.243 grams of Magnesium, how much hydrogen will be produced? Mg(s) + 2HCl(aq) à MgCl2(aq) + H2(g).

0.02 grams.

0.20 grams.

2.00 grams.

0.01 grams.

If you react 0.243 grams of magnesium, it will become 0.01 moles of magnesium. (0.243g/24.3g/mol). For every mole of magnesium reacted, a hydrogen mole is produced. Hence, 0.01 moles of H2 are generated, and are equivalent to 0.02 grams of hydrogen (0.01 mol x 2.0 g/mol).

Explanation

If you react 0.243 grams of magnesium, it will become 0.01 moles of magnesium. (0.243g/24.3g/mol). For every mole of magnesium reacted, a hydrogen mole is produced. Hence, 0.01 moles of H2 are generated, and are equivalent to 0.02 grams of hydrogen (0.01 mol x 2.0 g/mol).

77. Given the equation: N2(g) + O2(g) ßà 2NO(g) At 25oC the value of the equilibrium constant is 1 X 10-30. What happens to this equation?

The production of nitrogen and oxygen is favored

The production of nitrogen oxide is favored

Only the production of nitrogen is favored

Only the production of oxygen is favored

Because the equilibrium constant is so very small, very few products will be formed. The reverse reaction is favored, increasing the amount of nitrogen and oxygen.

Explanation

Because the equilibrium constant is so very small, very few products will be formed. The reverse reaction is favored, increasing the amount of nitrogen and oxygen.

78. When you deduce an explanation that follows from observations you have made, which of the following science process skills are you using?

Observation

Inference

Classification

Prediction

Inference is the process of coming up with or deducing an explanation for something based on observations which have been made. Prediction relates to anticipating the outcome of a process rather than describing its cause or mechanism.

Explanation

Inference is the process of coming up with or deducing an explanation for something based on observations which have been made. Prediction relates to anticipating the outcome of a process rather than describing its cause or mechanism.

79. How many particles of MgCl2 are there in 50g of magnesium chloride? Assume atomic masses of Mg = 24, and Cl = 35.

(50 / 94)

(50 / 94) * 6 x 1023

(50 / 59)

(50 / 59) * 6 x 1023

The atomic mass of (1 x 24) + (2 x 35) = 24 + 70 = 94.

To turn this into the number of moles requires the formula mass/atomic mass = 50/94. Then according to Avogadro’s constant there are 6 x 1023 particles in every mole.

Therefore the equation would be (50 / 94) * 6 x 1023.

Explanation

The atomic mass of (1 x 24) + (2 x 35) = 24 + 70 = 94.

To turn this into the number of moles requires the formula mass/atomic mass = 50/94. Then according to Avogadro’s constant there are 6 x 1023 particles in every mole.

Therefore the equation would be (50 / 94) * 6 x 1023.

80. An earthquake that registers an 8 on the Richter scale is how many times more powerful than one that registers a 5 on the Richter scale?

Three times.

1000 times.

30 times.

9 times.

The Richter scale is logarithmic, so an 8 is 108 and a 5 is 105. This means that an 8 is 103 times
larger than a 5, or 1000 times more powerful.

Explanation

The Richter scale is logarithmic, so an 8 is 108 and a 5 is 105. This means that an 8 is 103 times
larger than a 5, or 1000 times more powerful.

81. A radio tuner has a frequency range from 500kHz to 5MHz. If its LC circuit has an effective inductance of 400μH, what is the range of its variable capacitor? (Take π2=10).

2.5pF to 250pF.

5pF to 500pF.

7.5pF to 750pF.

10pF to 1000pF.

Frequency of oscillation of an LC circuit is ν=ω/2π=1/(2π√LC), or C=1/(4π2ν2L) in which L=400μH=400x10-6H. For ν=500kHz=500x103 Hz, C=1/(4π2x(500x103)2x400x106)= 250x10-12 F. Similarly, for ν= 1MHz=106 Hz, C=2.5pF. The range of the capacitor therefore, is 2.5pF to 250pF.

Explanation

Frequency of oscillation of an LC circuit is ν=ω/2π=1/(2π√LC), or C=1/(4π2ν2L) in which L=400μH=400x10-6H. For ν=500kHz=500x103 Hz, C=1/(4π2x(500x103)2x400x106)= 250x10-12 F. Similarly, for ν= 1MHz=106 Hz, C=2.5pF. The range of the capacitor therefore, is 2.5pF to 250pF.

82. Helen noticed that bridges had more ice on them than regular roads during the winter. She formulated a suggested explanation that it was because the road got colder there than elsewhere, and decided to slow down when crossing bridges. This reasonable proposal for why bridges are more icy than roads is an example of which of the following?

A scientific fact.

An inference.

A hypothesis.

An observation.

A suggested explanation or reasonable proposal for predicting causal correlations for a phenomenon is called a hypothesis. A hypothesis is a working explanation that can be tested using experimental procedures to determine its validity.

Explanation

A suggested explanation or reasonable proposal for predicting causal correlations for a phenomenon is called a hypothesis. A hypothesis is a working explanation that can be tested using experimental procedures to determine its validity.

83. The yellow light given off by sodium vapor lights has a wavelength of 589 nm. What is the frequency of this radiation?

5.09 X 1014 s-1

3.00 X 108 m/s

6.626 X 10-34 J-s

1.0 X 109 m

The speed of light is a constant, 3.00 X 108 m/s. The product of the frequency (n) and the wavelength (l) is equal to the speed of light (c). Therefore, the frequency is equal to the speed of light (c) / wavelength (l) or, [ 3.00 X 108m/s / 589 nm ] [ 1 nm / 10-9 m ] = 5.09 X 1014 s-1.
Because the wavelength is given in nanometers, you must convert it to meters. ( s-1 is an abbreviation for 1/sec.) (Round off the 589 to 600 to make the division easier.) 6.626 X 10-34 J-s is known as Planck’s constant measured in Joule-seconds.

Explanation

The speed of light is a constant, 3.00 X 108 m/s. The product of the frequency (n) and the wavelength (l) is equal to the speed of light (c). Therefore, the frequency is equal to the speed of light (c) / wavelength (l) or, [ 3.00 X 108m/s / 589 nm ] [ 1 nm / 10-9 m ] = 5.09 X 1014 s-1.
Because the wavelength is given in nanometers, you must convert it to meters. ( s-1 is an abbreviation for 1/sec.) (Round off the 589 to 600 to make the division easier.) 6.626 X 10-34 J-s is known as Planck’s constant measured in Joule-seconds.

84. Meteorologists commonly use which tool to measure the temperature and wind speed in the Earth's atmosphere at high altitude?

Doppler radar.

Rockets.

Satellites.

Weather balloons.

Doppler radar is used to measure wind speed and moisture content, but the most common tool used is the weather balloon. It can be used to measure temperature and wind speed high in the Earth's atmosphere.

Explanation

Doppler radar is used to measure wind speed and moisture content, but the most common tool used is the weather balloon. It can be used to measure temperature and wind speed high in the Earth's atmosphere.

85. Any charge can be divided into multiples of a minimum charge which is which of the following?

1.6x10-19C.

1C.

4πε0 C.

1/(4πε0) C.

The charge of a single electron is 1.6x10-19C. All charges are multiples of that value, since no charge smaller than that quantity has been found.

Explanation

The charge of a single electron is 1.6x10-19C. All charges are multiples of that value, since no charge smaller than that quantity has been found.

86. Charles Darwin is famous for developing the Theory of Evolution, but what other scientist was working on the same idea at the same time?

Lamarck.

Pomeroy.

Wallace.

Huxley.

Alfred Wallace independently proposed a theory of evolution due to natural selection, which prompted Darwin to publish his own theory.
Thomas Henry Huxley, an English biologist, became know as "Darwin's Bulldog" for his advocacy of evolution. His 1860 debate with Samuel Wilberforce was a key moment in the wider acceptance for the theory. Jean-Baptist Lemarck was a French naturalist and an early proponent for the idea of evolution. His theory involved a "ladder of complexity" for organisms.

Explanation

Alfred Wallace independently proposed a theory of evolution due to natural selection, which prompted Darwin to publish his own theory.
Thomas Henry Huxley, an English biologist, became know as "Darwin's Bulldog" for his advocacy of evolution. His 1860 debate with Samuel Wilberforce was a key moment in the wider acceptance for the theory. Jean-Baptist Lemarck was a French naturalist and an early proponent for the idea of evolution. His theory involved a "ladder of complexity" for organisms.

87. Alfred Wegner is famous for which geological theory?

Plate Tectonics Theory.

Uniformitarianism Theory.

The Continental Drift Theory.

Mineral Hardness Theory.

Alfred Wegner was the first person to publicly note how the Continents seemed to fit together. This led to the Theory of Continental Drift, an idea not well received at the time.

Explanation

Alfred Wegner was the first person to publicly note how the Continents seemed to fit together. This led to the Theory of Continental Drift, an idea not well received at the time.

88. What is the capacitance of a single spherical conductor?

Zero.

1/4πr.

4πr.

4πε0r.

In a single spherical conductor, the electric field is normal to the surface of the sphere. The potential is given by V=(1/4πε0)Q/r . Since C=Q/V, the capacitance is 4πε0r where ε0 is the permittivity of free space equal to 8.854x10-12 F/m.

Explanation

In a single spherical conductor, the electric field is normal to the surface of the sphere. The potential is given by V=(1/4πε0)Q/r . Since C=Q/V, the capacitance is 4πε0r where ε0 is the permittivity of free space equal to 8.854x10-12 F/m.

89. Which person in history can be considered to be the Father of the Modern Scientific Method?

Galileo.

Aristotle.

Roger Bacon.

Isaac Newton.

Galileo is most generally credited with being the father of the scientific method. By developing the tools of observation, hypothesis, mathematical deduction and confirmatory experiment, he founded the scientific methodology that we still use today.

Explanation

Galileo is most generally credited with being the father of the scientific method. By developing the tools of observation, hypothesis, mathematical deduction and confirmatory experiment, he founded the scientific methodology that we still use today.

90. Approximately how high is the higest mountain on Earth?

About 6,000 meters.

About 100,000 meters.

About 10,000 meters.

About 29,000 meters.

Mount Everest is 29,029 feet high, which is about 10,000 meters.

Explanation

Mount Everest is 29,029 feet high, which is about 10,000 meters.

91. How many ml of a 34,000 mg/L solution of sodium nitrate (NaNO3) will be required to contain 0.1 moles of sodium nitrate? (You may use 85.0 as the molecular weight of sodium nitrate).

200 ml.

250 ml.

300 ml.

350 ml.

The molar concentration of the solution is (34 g/L)/(85 g/mole) = 0.4 moles/L. The number of ml containing 0.1 moles is [(0.1 moles)/(0.4 moles/L)]*(1000 ml/L) = 250 ml.

Explanation

The molar concentration of the solution is (34 g/L)/(85 g/mole) = 0.4 moles/L. The number of ml containing 0.1 moles is [(0.1 moles)/(0.4 moles/L)]*(1000 ml/L) = 250 ml.

92. In an experiment, data was collected about the level of chemicals present in alluvial wells in alluvial wells in Kansas. Researchers were specifically interested in the amount of nitrate and chloride and whether the two were linked. The data collected was plotted on a scatter plot, which is shown above. Which of the following conclusions would be reasonable based on the data shown?

Conclusion II: In wells where there was an increased level of chloride, there was generally an increased level of nitrate

Conclusion III: In wells where there was an increased level of chloride, there was generally a decreased level of nitrate

Conclusion IV: It is not possible to draw any conclusions from the data

There appears to be an upwards diagonal trend in the pattern of the data points on the graph. A line has also been drawn in to show the general trend in the data. This shows some level of a positive correlation between chloride and nitrate. The association is not terribly strong, but the association is present.

Explanation

There appears to be an upwards diagonal trend in the pattern of the data points on the graph. A line has also been drawn in to show the general trend in the data. This shows some level of a positive correlation between chloride and nitrate. The association is not terribly strong, but the association is present.

93. Two thin lenses of focal lengths f1 and f2 are separated by a distance d. What is the focal length fc of the combined system?

Fc-1=f1-1-f2-1-df1-1f2-1.

Fc-1=f1-1+f2-1-df1-1f2-1.

Fc-1=f1-1+f2-1+df1-1f2-1.

Fc-1=f1-1*f2-1+df1-1f2-1.

If two thin lenses are separated by a distance d in air, the focal length for the combined system given is : fc-1=f1-1+f2-1-df1-1f2-1.

Explanation

If two thin lenses are separated by a distance d in air, the focal length for the combined system given is : fc-1=f1-1+f2-1-df1-1f2-1.

94. What theories is Albert Einstein not famous for?

The Photoelectric Effect.

The Theories of Relativity (General and Special).

The Quantum Uncertainty Principle.

The Theory of Density Fluctuation in Gases and Liquids.

Einstein's name is synonomous with genius, and has many theories connected to it. The Quantum (or Heisenburg) Uncertainty Principle however, is not one.

Explanation

Einstein's name is synonomous with genius, and has many theories connected to it. The Quantum (or Heisenburg) Uncertainty Principle however, is not one.

95. How many orders of magnitude difference are there between ten (10) milligrams and 100 kilograms?

10,000,000.

Three (3).

Nine (9).

Seven (7).

First, you must know the prefixes of the metric system: There are 1,000 milligrams in a gram, and 1,000 grams in a kilogram. One way of answering this question is to convert both values into the same unit as follows:

100 kilograms = 100,000,000 milligrams, which is sevenfold greater than ten (10).

Scientists use scientific notation to work with numbers that have many zeros, in order to avoid mistakes, and to make the math more efficient. In our question:
100 kilograms = 1 X 105 grams;

10 milligrams = 1 X 10-2 grams;

Taking the absolute difference 5-(-2) = 7 orders of magnitude.

Explanation

First, you must know the prefixes of the metric system: There are 1,000 milligrams in a gram, and 1,000 grams in a kilogram. One way of answering this question is to convert both values into the same unit as follows:

100 kilograms = 100,000,000 milligrams, which is sevenfold greater than ten (10).

Scientists use scientific notation to work with numbers that have many zeros, in order to avoid mistakes, and to make the math more efficient. In our question:
100 kilograms = 1 X 105 grams;

10 milligrams = 1 X 10-2 grams;

Taking the absolute difference 5-(-2) = 7 orders of magnitude.

96. Every so often, wind and currents can reiniforce themselves to produce an extremely large wave. This type of wave is called which of the following?

A tidal wave.

A rogue wave.

A tsunami.

A big wave.

Rogue waves can be generated with the reinforcement of wind and currents up to 120 feet high on the open ocean. It was once thought that rogue waves were very rare, but satellites have shown them to be more common.

Explanation

Rogue waves can be generated with the reinforcement of wind and currents up to 120 feet high on the open ocean. It was once thought that rogue waves were very rare, but satellites have shown them to be more common.

97. Which of the following cardiovascular system parts is associated with oxygen leaving the blood; and carbon dioxide entering the blood?

Arteries.

Veins.

Peripheral capillaries.

Pulmonary (alveolar) capillaries.

Capillaries are blood vessels of very small diameter with very thin walls that are extremely efficient at allowing gases and nutrients to cross into and out of blood. The pulmonary capillaries are associated with carbon dioxide, leaving blood and oxygen entering it, while the peripheral capillaries distribute oxygen to tissue, and remove the cellular respiration waste product, carbon dioxide.

Explanation

Capillaries are blood vessels of very small diameter with very thin walls that are extremely efficient at allowing gases and nutrients to cross into and out of blood. The pulmonary capillaries are associated with carbon dioxide, leaving blood and oxygen entering it, while the peripheral capillaries distribute oxygen to tissue, and remove the cellular respiration waste product, carbon dioxide.

98. For any particular trait, the pair of alleles of each parent separate and only one allele from each parent passes to an offspring. This idea is known as Mendel's Principle of which of the following?

Regular distribution.

Parental inheritance.

Transmission.

Segregation.

Genes occur in pairs, and during the process of gamete (sex cell) production, the members of each pair separate, or segregate, so that each sperm and ovum cell receives one member of each pair.

Explanation

Genes occur in pairs, and during the process of gamete (sex cell) production, the members of each pair separate, or segregate, so that each sperm and ovum cell receives one member of each pair.

99. A term used in popular culture to describe the psychological reaction of an individual or society to the fast pace of technological or social change is called which of the following?

Technophycosis.

Future shock.

Deltataxis.

Web's conundrum.

Future shock is a term that was coined by writer Alvin Toffler in 1970. It describes the psychological reaction of individuals or a society, to the fast pace of technological and social change.

Explanation

Future shock is a term that was coined by writer Alvin Toffler in 1970. It describes the psychological reaction of individuals or a society, to the fast pace of technological and social change.

100. Which of the following refers to the study of factors that can change gene expression or phenotype without changing the genetic sequence itself?

Eugenics.

Epigenetics.

Paragenetics.

Population genetics.

Epigenetics refers to changes in gene expression that are stable between cell divisions and sometimes between generations. Epigenetic gene expression traits can sometimes be heritable without requiring a change in DNA sequence.

Explanation

Epigenetics refers to changes in gene expression that are stable between cell divisions and sometimes between generations. Epigenetic gene expression traits can sometimes be heritable without requiring a change in DNA sequence.

101. Which of the following molecules is an alkene?

CH2CH2.

C2H6.

C5H8.

C2H5OH

CH2CH2 is ethene and has a double bond. An organic molecule with a double bond between carbons is an alkene. C2H6 is ethane and alkane, and has all single bonds. C5H8 is pentyne, and has a triple bond, making it an alkyne. C2H5OH is ethyl alcohol.

Explanation

CH2CH2 is ethene and has a double bond. An organic molecule with a double bond between carbons is an alkene. C2H6 is ethane and alkane, and has all single bonds. C5H8 is pentyne, and has a triple bond, making it an alkyne. C2H5OH is ethyl alcohol.

102. Two small and heavy spheres, each of mass M, are placed a distance r apart on a horizontal surface. The gravitational field intensity at the mid point of the line joining the centers of the spheres is

Zero

GM2/r2

GM2/2r2

GM2/4r2

Gravitational field intensity at a point is defined as the the gravitational field experienced by a unit mass placed at that point. Since the spheres have the same mass, the gravitational forces exerted by the each sphere on a unit mass placed at the mid-point will be equal and opposite. Hence, the net gravitational field is zero.

Explanation

Gravitational field intensity at a point is defined as the the gravitational field experienced by a unit mass placed at that point. Since the spheres have the same mass, the gravitational forces exerted by the each sphere on a unit mass placed at the mid-point will be equal and opposite. Hence, the net gravitational field is zero.

103. Sodium has an atomic number of 11. How many electrons does a sodium ion have?

10

11

12

22

Sodium is positively charged when it is an ion (a cation). Therefore it must have one less electron in its cation state. We know that since the atomic number of sodium is 11, it must have 11 protons and 11 electrons in its nonionic form. As a cation, sodium has one less electron or ten electrons.

Explanation

Sodium is positively charged when it is an ion (a cation). Therefore it must have one less electron in its cation state. We know that since the atomic number of sodium is 11, it must have 11 protons and 11 electrons in its nonionic form. As a cation, sodium has one less electron or ten electrons.

104. The study of rock layers and how they relate to one another is which of the following?

Stratigraphy.

Stratilology

Sedimentary science.

Stratification science.

Stratigraphy is the study of rock layers and layering, or stratification. It is mostly used in the study of sedimentary or layered volcanic rocks.

Explanation

Stratigraphy is the study of rock layers and layering, or stratification. It is mostly used in the study of sedimentary or layered volcanic rocks.

105. The carbon dioxide in a carbonated beverage is an example of a gas dissolved in a liquid. Which of the following will increase the rate of dissolution of a gas in a liquid? A. Increase the temperature of the mixture. B. Increase the gas pressure on the liquid. C. Stir the mixture. D. Use more liquid and gas.

A and B only

B and C only

A, B, and C only

B, C, and D only

Increasing the gas pressure on the liquid and stirring the mixture would increase the rate of dissolution of a gas into a liquid. However, decreasing the temperature, would help rather than increasing the temperature. The total amount of liquid and gas would have no effect.

Explanation

Increasing the gas pressure on the liquid and stirring the mixture would increase the rate of dissolution of a gas into a liquid. However, decreasing the temperature, would help rather than increasing the temperature. The total amount of liquid and gas would have no effect.

106. Which molecule is never bound to the active site of an enzyme?

Substrate

Product

Competitive inhibitor

Noncompetitive inhibitor

The substrate binds to the active site of an enzyme and is converted into the product. The product is temporarily bound to the active site but dissociates quickly. A competitive inhibitor challenges or competes with the substrate for position at the active site of the enzyme. Thus a competitive inhibitor physically prevents the substrate from binding to the enzyme by binding instead. A noncompetitive inhibitor binds at a site other than the active site and changes the conformation of the protein so the substrate cannot bind.

Explanation

The substrate binds to the active site of an enzyme and is converted into the product. The product is temporarily bound to the active site but dissociates quickly. A competitive inhibitor challenges or competes with the substrate for position at the active site of the enzyme. Thus a competitive inhibitor physically prevents the substrate from binding to the enzyme by binding instead. A noncompetitive inhibitor binds at a site other than the active site and changes the conformation of the protein so the substrate cannot bind.

107. The Biotic Theory is best described by which of the following?

Changes in climate act as density-dependent agents.

Populations may be limited by changes in the behavior and physiology of the individuals in the population.

Populations are limited by the predators that exist in the same geographical area.

Natural enemies are thought to be the major limiting factor in population growth.

This is an integral part of the Biotic Theory: Natural enemies will result in a decreased population size. Climatic Theory: Climate is not density-dependent. It affects all organisms equally, regardless of population size. Self-Regulation Theory: Populations may be limited by changes in the behavior and physiology of the individuals in the population. That includes genetics, and has to do with reproduction. A high number of predators will affect the number of prey eventually-but, it does not describe the Biotic Theory.

Explanation

This is an integral part of the Biotic Theory: Natural enemies will result in a decreased population size. Climatic Theory: Climate is not density-dependent. It affects all organisms equally, regardless of population size. Self-Regulation Theory: Populations may be limited by changes in the behavior and physiology of the individuals in the population. That includes genetics, and has to do with reproduction. A high number of predators will affect the number of prey eventually-but, it does not describe the Biotic Theory.

108. When the following redox equation in an acidic solution is balanced, what is the coefficient in front of the chlorine gas? Cr2O72-(aq) + Cl-1(aq) à Cr3+(aq) + Cl2(g)

6

3

2

1

The balanced equation is:
14 H+(aq) +Cr2O72-(aq) +6 Cl-1(aq) à 2 Cr3+(aq) +7 H2O(l) + 3Cl2(g)
In acidic solutions redox reactions need H+ ions added to either side of the equation to balance hydrogens. Water is added to balance the oxygen atoms in the original equation.

Explanation

The balanced equation is:
14 H+(aq) +Cr2O72-(aq) +6 Cl-1(aq) à 2 Cr3+(aq) +7 H2O(l) + 3Cl2(g)
In acidic solutions redox reactions need H+ ions added to either side of the equation to balance hydrogens. Water is added to balance the oxygen atoms in the original equation.

109. A motor with an armature of resistance 2Ω is designed to operate at 220V. At full speed, it develops a back emf of 210V. When the motor is switched on, what is the current in the armature if a starter is not used?

Zero.

5.0A.

110A.

220A.

When the motor is switched on, Eb=0 since the initial speed of the armature is zero. If a starter is not used, the starting current in the armature will be Is= Ea/Ra= 220/2=110A, which is sure to burn out the armature. Hence, a starter must be used with the armature when the motor is initially switched on.

Explanation

When the motor is switched on, Eb=0 since the initial speed of the armature is zero. If a starter is not used, the starting current in the armature will be Is= Ea/Ra= 220/2=110A, which is sure to burn out the armature. Hence, a starter must be used with the armature when the motor is initially switched on.

110. A missile is fired at your town from maximum range from a place in the enemy country that is 100km away. What is the velocity at which the missile strikes the target, assuming that g=10m/s2?

102m/s.

103m/s.

104m/s.

105m/s.

Given that Rmax=100km=105m. Since the missile is fired from maximum range, the angle of projection is 45°. The initial velocity of the missile is v0=√(g x Rmax)= √(10x105)= 103 m/s.The final velocity is the same as the velocity of projection, which is 103m/s.

Explanation

Given that Rmax=100km=105m. Since the missile is fired from maximum range, the angle of projection is 45°. The initial velocity of the missile is v0=√(g x Rmax)= √(10x105)= 103 m/s.The final velocity is the same as the velocity of projection, which is 103m/s.

111. Tidal waves, or tsunamis can be caused by any of the following forces, EXCEPT which of the following?

Seismic activity.

Landslides.

Tidal bores.

Volcanoes.

A tidal bore occurs when the leading edge of an incoming tide forms a wave as it travels up a river or narrow bay against the direction of the current. Tidal bores are sometimes called "tidal waves", but they are not true tsunamis.

Explanation

A tidal bore occurs when the leading edge of an incoming tide forms a wave as it travels up a river or narrow bay against the direction of the current. Tidal bores are sometimes called "tidal waves", but they are not true tsunamis.

112. Which of the following names can be applied to the chemical formula Cu2HPO4? I: Cupric biphosphate. II: Cuprous biphosphate. III: Copper (II) biphosphate. IV: Copper (I) biphosphate.

I and III.

II and III.

I and IV.

II and IV.

First you need to determine the charge of the copper ion.

The key to determining this is to know that HPO4 (biphosphate) has a charge of -2

Since HPO4 has a charge of -2, each of two copper ions must have a charge of +1 to make sure the net charge of the molecule is zero

Cu+1 + Cu+1 + (HPO4)-2 = Cu2HPO4

When the copper ion has a charge +1, the name given is "cuprous" or "copper (I)".

So the name of this molecule can be either Cuprous biphosphate or Copper (I) biphosphate

Explanation

First you need to determine the charge of the copper ion.

The key to determining this is to know that HPO4 (biphosphate) has a charge of -2

Since HPO4 has a charge of -2, each of two copper ions must have a charge of +1 to make sure the net charge of the molecule is zero

Cu+1 + Cu+1 + (HPO4)-2 = Cu2HPO4

When the copper ion has a charge +1, the name given is "cuprous" or "copper (I)".

So the name of this molecule can be either Cuprous biphosphate or Copper (I) biphosphate

113. Which is the correct ionic formula for a molecule of sulfite?

SO32- .

SO3-.

SO42-.

SO4- .

Most oxygen-containing anions end in the suffix, ‘-ate’, but if there is a similar molecule with less oxygen ions, the correct suffix to use is ‘-ite’. Therefore, SO42- is sulfate while SO32- has one less oxygen atom, is sulfite. Neither of those is associated with a single negative charge; but rather are both associated with a charge of 2-.

Explanation

Most oxygen-containing anions end in the suffix, ‘-ate’, but if there is a similar molecule with less oxygen ions, the correct suffix to use is ‘-ite’. Therefore, SO42- is sulfate while SO32- has one less oxygen atom, is sulfite. Neither of those is associated with a single negative charge; but rather are both associated with a charge of 2-.

114. The rule in geology that states that newer layers will generally be on the top and older layers on the bottom is called which of the following?

The rule of sedimentation.

The law of supposition.

The law of stratification.

Uniformitarianism.

The law of supposition states that when you look at a cross-section of sedimentary rock, the older layers are on the bottom, and the newer layers on the top. That Law is used in geology to age sedimentary rock, and the fossils found within them.

Explanation

The law of supposition states that when you look at a cross-section of sedimentary rock, the older layers are on the bottom, and the newer layers on the top. That Law is used in geology to age sedimentary rock, and the fossils found within them.

115. The displacement of a body from a reference point is given by √x= 2t+3, where x is in meters and t is in seconds. What is the acceleration of the body?

2m/s2.

3m/s2.

6m/s2.

8m/s2.

√x= 2t+3. Squaring both sides, x=4t2+12t+9. Differentiating with respect to t, dx/dt=8t+12. Differentiating with respect to time again, d2x/dt2=8. Hence, the acceleration is 8m/s2.

Explanation

√x= 2t+3. Squaring both sides, x=4t2+12t+9. Differentiating with respect to t, dx/dt=8t+12. Differentiating with respect to time again, d2x/dt2=8. Hence, the acceleration is 8m/s2.

116. Two blocks of mass, m1 and m2 are placed in contact on a frictionless surface. When a force F is applied on the block with mass m1, how much force does it apply on the other block?

(m1/m2)•F.

(m2/m1)•F.

M1•F/(m1+m2).

M2•F/(m1+m2).

When a force is applied on the block of mass m1, because it is in contact with block m2, both of them move with the same acceleration F/(m1+m2). The force on the block with mass m1 is m1•F/(m1+m2). The force exerted by the block on the other is m2•F/(m1+m2).

Explanation

When a force is applied on the block of mass m1, because it is in contact with block m2, both of them move with the same acceleration F/(m1+m2). The force on the block with mass m1 is m1•F/(m1+m2). The force exerted by the block on the other is m2•F/(m1+m2).

117. Stellar parallax shift can be used to measure the distance between a star and the Earth. So when the parallax shift is larger, which of the following is occurring?

The closer the star is to Earth.

The farther the star is from Earth.

The smaller the parallax angle.

The easier it is to determine the distance.

The greater a star shift on a background of stars, the larger the parallax angle; and the closer that the star is to Earth. Through the application of trigonometry we are able to determine that the larger the shift angle, the shorter the distance to Earth.

Explanation

The greater a star shift on a background of stars, the larger the parallax angle; and the closer that the star is to Earth. Through the application of trigonometry we are able to determine that the larger the shift angle, the shorter the distance to Earth.

118. The motion of a body is given by dv/dt=6-3v, in which v is the velocity in m/s at a time, t. If the body were at rest at t=0, what would the body speed be with the acceleration at half the initial value?

1m/s.

2m/s.

3m/s.

6m/s.

The acceleration is given by a=dv/dt=6-3v. The initial acceleration is 6m/s2. When it is half that value, 3=6-3v, or v=1m/s.

Explanation

The acceleration is given by a=dv/dt=6-3v. The initial acceleration is 6m/s2. When it is half that value, 3=6-3v, or v=1m/s.

119. According to current theory, only two things are necessary for the creation of a star. What are they?

Hydrogen and helium.

Gravity and hydrogen.

Interstellar gas and gravity.

Hydrogen and oxygen.

Hydrogen and gravity are all that is necessary to initiate the burning of a new star. The collapsing of hydrogen by gravity creates a stellar pressure that balances the collapsing forces, and then fusion is initiated, creating a new star.

Explanation

Hydrogen and gravity are all that is necessary to initiate the burning of a new star. The collapsing of hydrogen by gravity creates a stellar pressure that balances the collapsing forces, and then fusion is initiated, creating a new star.

120. The Series RLC circuit in the figure is connected to a variable frequency 200V source. L=5H, C=80 μF and R=40Ω. The current amplitude of the circuit at resonance is which of the following?

50/√2 A.

5A.

5√2 A.

10A.

Current amplitude at resonance is I0= V0/Z= V0/R= √2 Vrms/R= √2 x 200/40= 5√2 A.

Explanation

Current amplitude at resonance is I0= V0/Z= V0/R= √2 Vrms/R= √2 x 200/40= 5√2 A.

PRAXIS Science III

1. Which two criteria are necessary and sufficient for something to be classified as matter?

2.

What first name or nickname would you like us to use?

2. What does the symbol above mean in organic chemistry?

3. While cloud gazing, Bobby tells Susan that he can name three different types of clouds. If he was right, what were three types of clouds that Bobby named?

4. Harold is the only one in his class with red hair. He has the highest grade in the class. James concludes that red hair makes Harold smarter than everyone in his class. Which of the following describes the error that James has made?

5. The earth's atmosphere consists of three major gases . Which is the most abundant gas?

7. When the relative humidity of the air is high, which of the following does it mean?

8. Out of the following list, which option is the most powerful way of conserving the Earth's resources and saving energy?

9. Kepler's First Law states which of the following?

10. A thirsty chemist accidentally makes some ice water from normal ice cubes and ice cubes using water containing deuterium instead of hydrogen. How can he simply determine which of the ice cubes are made of D2O before he takes a drink?

11. The increase of CO2 in the atmosphere is mainly the result of which of the following?

12. Places at mid latitudes have distinct seasons.Why is it hotter in the summer and colder in the winter in the Northern Hemisphere?

13. What evidence does not support the Plate Tectonic Theory?

14. Which of the following laws of thermodynamics is an expression of the principle of conservation of energy?

15. There used to be nine planets until Pluto was downgraded to a dwarf planet. Which of the following lists includes the eight remaining planets in their order from the sun?

16. What does the graph illustrate best?

17. In scientific inquiry, an attitude of reserved doubt or suspended judgment toward information until all the evidence is carefully examined is called which of the following?

18. Which is the largest ocean on earth?

19. What are the elements with complete electron shell configurations called?

20. Science classes sometimes promote the idea that all meaningful questions have quantitative right answers and that open-ended questions do not merit attention. What best illustrates that contention to be inaccurate?

22. Identify the specific element that corresponds to the following electron configuration. [Kr] 5s2 4d10 5p4

23. Under which of the following circumstance(s) is a teacher specifically and legally liable?

24. A total of 800 joules of energy is added to ten (10) grams of a liquid, causing it to increase in temperature from 23oC to 63oC. What is the heat capacity of the liquid?

25. In a safe lab, electricity and which of the following do not mix?

26. In a debate, an opponent of organic farming argues that organic food is considered no more nutritious than food that is regularly grown. Which of the following might be an environmental and health-related argument that a pro-organic debator might make in response?

27. The failure of a lens to focus all colors to the same point is called which of the following?

28. From the above graph of heat applied versus temperature what approximately is the temperature of vaporization of zinc?

29. Who is credited with the discovery of the double helix structure of DNA?

30. A scientist carefully isolates a nerve cell from a rat, and places it in a dish filled with liquid. Over a matter of minutes, the cell appears to get bigger even though he has not changed the optics. Which of the following is the most likely explanation for that occurrence?

31. Approximately how many days are there in an Earth year?

32. What type of terrestrial biome supports the growth of large, deciduous trees?

33. Given an unknown liquid, Bethany wants to design an experiment that will determine whether the solution is ionic or not. Which one of the following tests will be most helpful to her?

34. Convert a temperature of 100 oC to absolute temperature in oK, to the nearest whole number.

35. What is a very important consideration when considering the ethics of pre-natal testing?

36. Why are astronauts able to walk on the moon?

37. Why is using simple solar distillers a more elegant solution than a more high tech solution for addressing Third World water quality problems?

38. As a project, students will be studying the effect of light on the algae growth. Which of the following is the independent variable?

39. The unit of measurement of the optical power of a lens is which of the following?

40. The coefficient of thermal conductivity of a metallic rod depends on

41. Which is the correct name of the compound K2S?

42. Cody was trying to show that the mountain pine beetle populations were higher after a year with a mild winter. What would be the best data collection method for his study?

43. Which water cycle phase is represented in the graphic?

44. Human blood pH is closest to which of the following values?

45. Which of the following is true of the primary growth of a tree?

46. Theoretically, the absolute lowest temperature is

47. The meteorological effect of a coastline with high mountains will cause which of the following?

48. When it is below freezing, rain turns into snow. About how many inches of snow are there in one inch of rain?

49. What is oxidation number of sulfur in H2SO4?

50. What name is given to the molecule that should technically be known as dihydrogen dioxide?

51. Kelly observed strange beads of dirt with small holes next to them on his front lawn after every rain. What kind of scientific investigation could he conduct to find out what formed those holes and beads?

52. The relative density of ice is 0.9 and that of sea-water is 1.125. What fraction of the whole volume of an iceberg appears above the surface of the sea?

53. Why are eukaryotic cells within an organism different? For example, skin cells are different from neurons.

54. Which of the following configurations of resistors has the least total resistance? (All the resistors used are of 1 ohm)

55. Which disease might have the potential to cause society the most harm?

56. What is DNA wrapped around in a nucleosome?

57. Choose the correct option. In planetary motion

58. What is apparently wrong with the data below? 1 2 3 4 5 1 4 9 14 25

59. Every day an average of two people are born for every one that dies, leaving a ratio of 2 to 1 for births to deaths. What would happen to this ratio if the average life expectancy were to double?

60. Based on the drawing above, what season in the Northern Hemisphere is being illustrated?

61. Which of the following does not describe the forces of competition on species?

62. On messenger RNA (mRNA), how many nucleotides are in each codon?

63. The latent heat of fusion of water at 0oC is 334 J/g, and its latent heat of vaporization at the same temperature is 2501 J/g. What is the latent heat of sublimation of water at 0oC?

64. If the "reactant side" of a chemical reaction equation is: 2 NH3(g) + 3 N2O(g) → , then how many atoms of nitrogen must be present on the "product side" of the equation?

65. What is one of the toughest ethical questions about using technology to extend human life?

66. When white light is refracted in glass, which of the constituent colors is refracted the most?

67. The equation for the dissociation of nitrous acid is: HNO2 = H+ + NO2 - . If a solution of nitrous acid which is 0.0026N has a pH of 3, what is Ka for nitrous acid?

68. Which of the following refers to the genetic divergence of one or more populations from a single parent species inhabiting the same geographic region, to a degree such that those populations become different species?

69. An observer moves toward a stationary sound source with a velocity that is one-tenth (1/10th) of the velocity of sound. The apparent increase in frequency is which of the following?

70. Human cloning has the potential to provide organs for the sick, but also to create severely deformed beings. There are many ethical points that need to be considered. What do you think that the best course on human cloning should be?

71. Which of the following is true regarding the movement of sap from a sugar source to a sugar sink?

72. Which of the following best defines a closed population?

73. The most common salt in the ocean is which of the following?

74. Normal fruit flies have red eyes, but a scientist notices that a male fly has white eyes. He breeds the male with white eyes to three females with red eyes. Their offspring are listed in the table above. What can be said about the inheritance of white eyes in fruit flies?

75. A +1 diopter lens with a +3 diopter lens would give which of the following?

76. If you react 0.243 grams of Magnesium, how much hydrogen will be produced? Mg(s) + 2HCl(aq) à MgCl2(aq) + H2(g).

77. Given the equation: N2(g) + O2(g) ßà 2NO(g) At 25oC the value of the equilibrium constant is 1 X 10-30. What happens to this equation?

78. When you deduce an explanation that follows from observations you have made, which of the following science process skills are you using?

79. How many particles of MgCl2 are there in 50g of magnesium chloride? Assume atomic masses of Mg = 24, and Cl = 35.