Exam 3 - Pre-AP Chem - Shadrick
An exam covering electrons in atoms, periodic properties, ionization, the mole concept, and the kinetic-molecular theory.
Questions and Answers
- 1.
In which of the following states of matter can the molecules be compressed to a smaller volume?
- A.
Solid
- B.
Liquid
- C.
Gas
- D.
Liquid AND gas
Correct Answer
C. GasExplanation
In the gas state of matter, the molecules are spread out and have a lot of empty space between them. This means that there is room for the molecules to be compressed and brought closer together, resulting in a smaller volume. In contrast, in the solid and liquid states, the molecules are already tightly packed and do not have much room to be compressed further. Therefore, the correct answer is gas.Rate this question:
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- 2.
According to the kinetic-molecular theory, particles of matter are in motion in
- A.
Gases only
- B.
Gases and liquids
- C.
Solids, liquids, and gases
- D.
Solids only
Correct Answer
C. Solids, liquids, and gasesExplanation
According to the kinetic-molecular theory, particles of matter are in motion in solids, liquids, and gases. This theory states that all particles of matter are constantly moving and have kinetic energy. In solids, the particles vibrate in fixed positions, while in liquids, the particles are able to move past each other but still remain close together. In gases, the particles move freely and are far apart. Therefore, the kinetic-molecular theory applies to all three states of matter, solids, liquids, and gases.Rate this question:
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- 3.
If there are 760 mm Hg in 1 atmosphere, convert the pressure 0.75 atm to mm Hg.
- A.
1013 mm Hg
- B.
430 mm Hg
- C.
570 mm Hg
- D.
760 mm Hg
Correct Answer
C. 570 mm HgExplanation
To convert 0.75 atm to mm Hg, we can use the conversion factor of 760 mm Hg = 1 atm. By multiplying 0.75 atm by 760 mm Hg/1 atm, we get 570 mm Hg. Therefore, the pressure of 0.75 atm is equivalent to 570 mm Hg.Rate this question:
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- 4.
What instrument measures the pressure of an enclosed gas?
- A.
Barometer
- B.
Manometer
- C.
U-tube
- D.
Torrometer
Correct Answer
B. ManometerExplanation
A manometer is an instrument used to measure the pressure of an enclosed gas. It consists of a U-shaped tube filled with a liquid, such as mercury or water, and the gas pressure is determined by the difference in the heights of the liquid columns in the two arms of the tube. By measuring this difference, the pressure of the gas can be accurately determined. Therefore, a manometer is the correct instrument for measuring the pressure of an enclosed gas.Rate this question:
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- 5.
Convert the pressure 1.30 atmospheres to kilopascals. Remember that 1 atm = 101.3 kPa.
- A.
2 kPa
- B.
115 kPa
- C.
132 kPa
- D.
245 kPa
Correct Answer
C. 132 kPaExplanation
The correct answer is 132 kPa. To convert atmospheres to kilopascals, we can use the conversion factor 1 atm = 101.3 kPa. Therefore, to convert 1.30 atmospheres to kilopascals, we multiply 1.30 by 101.3, which gives us 132.99 kPa. Rounding this to the nearest whole number, we get 132 kPa.Rate this question:
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- 6.
How many moles are in 4.8 x 1025 atoms of W?
- A.
797 mol
- B.
79.7 mol
- C.
0.13 mol
- D.
0.013 mol
Correct Answer
B. 79.7 molExplanation
The given question is asking for the number of moles in 4.8 x 10^25 atoms of W. To find the number of moles, we need to divide the given number of atoms by Avogadro's number, which is approximately 6.022 x 10^23. When we divide 4.8 x 10^25 by 6.022 x 10^23, we get approximately 79.7 mol. Therefore, the correct answer is 79.7 mol.Rate this question:
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- 7.
How many molecules are in 2.10 mol CO2?
- A.
2.87 x 1024 molecules
- B.
3.79 x 1024 molecules
- C.
3.49 x 10-24 molecules
- D.
1.26 x 1024 molecules
Correct Answer
D. 1.26 x 1024 moleculesExplanation
The number of molecules in a given amount of substance can be calculated using Avogadro's number, which is approximately 6.022 x 10^23 molecules/mol. In this case, we have 2.10 mol of CO2. To find the number of molecules, we multiply the number of moles by Avogadro's number: 2.10 mol * 6.022 x 10^23 molecules/mol = 1.26 x 10^24 molecules. Therefore, the correct answer is 1.26 x 10^24 molecules.Rate this question:
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- 8.
What is the mass of one mole of AuCl3?
- A.
96 g
- B.
130 g
- C.
232.5 g
- D.
303.6 g
Correct Answer
D. 303.6 gExplanation
One mole of AuCl3 has a mass of 303.6 g. This is because the molar mass of AuCl3 is calculated by adding up the atomic masses of one atom of gold (Au) and three atoms of chlorine (Cl). The atomic mass of Au is 196.97 g/mol, and the atomic mass of Cl is 35.45 g/mol. Therefore, the molar mass of AuCl3 is (196.97 g/mol) + 3(35.45 g/mol) = 303.6 g/mol.Rate this question:
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- 9.
What is the number of moles in 432 grams of Ba(NO3)2?
- A.
0.237 mol
- B.
0.605 mol
- C.
1.65 mol
- D.
3.66 mol
Correct Answer
C. 1.65 molExplanation
The number of moles in a substance can be calculated by dividing the mass of the substance by its molar mass. In this case, the molar mass of Ba(NO3)2 is calculated by adding the atomic masses of each element in the compound. The molar mass of Ba(NO3)2 is 261.34 g/mol. Dividing the given mass of 432 grams by the molar mass gives a result of approximately 1.65 mol. Therefore, the correct answer is 1.65 mol.Rate this question:
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- 10.
What period of elements on the Periodic Table tends to have the highest ionization energy? the lowest?
- A.
1, 7
- B.
7, 1
- C.
2, 3
- D.
18, 1
Correct Answer
A. 1, 7Explanation
Elements in Group 1 (1) tend to have the lowest ionization energy because they have only one valence electron, which is relatively easy to remove. On the other hand, elements in Group 7 (7) tend to have the highest ionization energy because they have seven valence electrons and are close to achieving a stable octet. Removing an electron from these elements requires a significant amount of energy. Therefore, the elements in Group 1 have the lowest ionization energy, while the elements in Group 7 have the highest ionization energy.Rate this question:
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- 11.
In this diagram, what is the first ionization energy for sodium?
- A.
496 kJ/mol
- B.
521 kJ/mol
- C.
738 kJ/mol
- D.
899 kJ/mol
Correct Answer
A. 496 kJ/molExplanation
The first ionization energy for sodium is 496 kJ/mol. This is the amount of energy required to remove one electron from a sodium atom in its gaseous state. A lower ionization energy indicates that it is easier to remove an electron, which is the case for sodium compared to the other options given.Rate this question:
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- 12.
Which of the following ions does NOT have an octet?
- A.
Al3+
- B.
Cl-
- C.
Mg2+
- D.
O-
Correct Answer
D. O-Explanation
Oxygen typically forms an octet by gaining two electrons to achieve a stable electron configuration. However, in the case of O-, it has an extra electron, resulting in a total of nine electrons. This ion has an odd number of electrons and does not have an octet, making it the correct answer.Rate this question:
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- 13.
How does a nitrogen atom most commonly achieve an octet of electrons?
- A.
By gaining 5 electrons
- B.
By gaining 3 electrons
- C.
By losing 5 electrons
- D.
By losing 3 electrons
Correct Answer
B. By gaining 3 electronsExplanation
A nitrogen atom most commonly achieves an octet of electrons by gaining 3 electrons. Nitrogen has 5 valence electrons, and it needs 3 more electrons to complete its outer shell and achieve stability. By gaining 3 electrons, nitrogen can fill its outer shell and reach a total of 8 electrons, which is the octet configuration commonly found in stable atoms.Rate this question:
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- 14.
What charge does the atom in this diagram have?
- A.
-1
- B.
+2
- C.
+1
- D.
+3
Correct Answer
C. +1Explanation
Based on the given options, the atom in the diagram has a charge of +1.Rate this question:
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- 15.
How does the atomic radius change from top to bottom in a group in the Periodic Table?
- A.
It tends to decrease.
- B.
It tends to increase.
- C.
It first increases, then decreases.
- D.
It first decreases, then increases.
Correct Answer
B. It tends to increase.Explanation
The atomic radius refers to the size of an atom. As you move down a group in the periodic table, the number of energy levels or shells increases. This means that the outermost electrons are further away from the nucleus, resulting in an increase in atomic radius. Therefore, the correct answer is that the atomic radius tends to increase from top to bottom in a group.Rate this question:
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- 16.
Which element in the second period has the largest atomic radius?
- A.
Ra
- B.
Li
- C.
K
- D.
Ne
Correct Answer
B. LiExplanation
Li is the element in the second period with the largest atomic radius. This is because atomic radius generally decreases across a period from left to right due to increasing nuclear charge and electron-electron repulsion. However, Li is an exception to this trend. It has a larger atomic radius compared to Be because it has an extra electron shell, which increases the distance between the nucleus and the outermost electrons, resulting in a larger atomic radius.Rate this question:
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- 17.
Which of the following elements has the smallest atomic radius?
- A.
S
- B.
Cl
- C.
Se
- D.
Br
Correct Answer
B. ClExplanation
The correct answer is Cl. Atomic radius refers to the size of an atom, which is determined by the distance between the nucleus and the outermost electron shell. As we move across a period in the periodic table from left to right, the atomic radius generally decreases. Chlorine (Cl) is located to the right of sulfur (S), selenium (Se), and bromine (Br), so it has the smallest atomic radius among these elements.Rate this question:
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- 18.
Of the following elements, which has the lowest electronegativity value?
- A.
Cs
- B.
At
- C.
Ca
- D.
F
Correct Answer
A. CsExplanation
Cs (Cesium) has the lowest electronegativity value among the given elements. Electronegativity is a measure of an atom's ability to attract electrons towards itself in a chemical bond. Cs is located towards the bottom left of the periodic table, in the alkali metal group, and has a large atomic radius. These factors contribute to its low electronegativity value. In contrast, At (Astatine) is a halogen and has a higher electronegativity value compared to Cs. Ca (Calcium) is an alkaline earth metal and has a higher electronegativity value than Cs. F (Fluorine) is the most electronegative element and has the highest electronegativity value among the given options.Rate this question:
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- 19.
Of the following elements, which has the highest electronegativity value?
- A.
Li
- B.
C
- C.
Br
- D.
F
Correct Answer
D. FExplanation
Fluorine (F) has the highest electronegativity value among the given elements. Electronegativity refers to an atom's ability to attract electrons towards itself in a chemical bond. Fluorine is the most electronegative element in the periodic table, meaning it has the strongest ability to attract electrons. This is due to its small atomic size and high effective nuclear charge.Rate this question:
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- 20.
Which of the following factors contributes to the decrease in ionization energy within a group in the periodic table, as the atomic number increases?
- A.
Increase in atomic size
- B.
Increase in the number of neutrons
- C.
Increase in the number of protons
- D.
Fewer electrons in the highest occupied energy level
Correct Answer
A. Increase in atomic sizeExplanation
As the atomic number increases within a group in the periodic table, the size of the atoms also increases. This is because each successive element has an additional electron shell, which results in a larger atomic radius. As the atomic size increases, the outermost electron is farther away from the positively charged nucleus, resulting in a weaker attraction between the electron and the nucleus. This weaker attraction requires less energy to remove the outermost electron, leading to a decrease in ionization energy.Rate this question:
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- 21.
One atom of argon would have a mass of how many grams?
- A.
39.9 g
- B.
2.40 x 10-25 g
- C.
6.63 x 10-23 g
- D.
1.66 x 10-24 g
Correct Answer
C. 6.63 x 10-23 gExplanation
The correct answer is 6.63 x 10-23 g. This is because the atomic mass of argon is approximately 39.9 atomic mass units (amu), and since 1 amu is equivalent to 1.66 x 10-24 g, we can calculate the mass of one atom of argon by multiplying the atomic mass by the conversion factor. Therefore, 39.9 amu * 1.66 x 10-24 g/amu = 6.63 x 10-23 g.Rate this question:
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- 22.
Which of the following is NOT a part of the Kinetic-Molecular Theory?
- A.
All gases are composed of particles.
- B.
Atoms cannot be created or destroyed in a chemical reaction.
- C.
Molecules undergo completely elastic collisions.
- D.
Molecules and atoms are constantly moving, except at absolute zero.
Correct Answer
B. Atoms cannot be created or destroyed in a chemical reaction.Explanation
The Kinetic-Molecular Theory explains the behavior of gases based on the idea that gases are composed of particles (atoms or molecules) that are in constant motion. It states that these particles undergo completely elastic collisions, meaning that no energy is lost during collisions. Additionally, it states that molecules and atoms are constantly moving, except at absolute zero temperature. The statement "Atoms cannot be created or destroyed in a chemical reaction" is not a part of the Kinetic-Molecular Theory, as it pertains more to the Law of Conservation of Mass, which states that matter cannot be created or destroyed in a chemical reaction.Rate this question:
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- 23.
Which of these statements about elastic collisions is true?
- A.
The average distance between particle collisions is called mean free path.
- B.
In an elastic collision, the colliding objects fuse together and stop moving.
- C.
Two cars crashing in a parking lot is an example of an elastic collision.
Correct Answer
A. The average distance between particle collisions is called mean free path.Explanation
The correct answer is: The average distance between particle collisions is called mean free path.
In physics, the mean free path is the average distance traveled by a particle between successive collisions with other particles. It is a measure of how far a particle can travel before it collides with another particle. This concept is commonly used in the study of gases, where the mean free path determines the likelihood of collisions and the behavior of particles. It is not related to elastic collisions, where colliding objects bounce off each other without any loss of kinetic energy.Rate this question:
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- 24.
In this diagram, the height difference in the two columns of mercury is 100 mm. If the measured atmospheric pressure is 760 mm Hg, what is the pressure of the contained gas?
- A.
100 mm Hg
- B.
660 mm Hg
- C.
760 mm Hg
- D.
860 mm Hg
Correct Answer
D. 860 mm HgExplanation
The height difference in the two columns of mercury represents the pressure difference between the atmosphere and the contained gas. Since the height difference is 100 mm and the atmospheric pressure is 760 mm Hg, the pressure of the contained gas must be 760 mm Hg + 100 mm Hg = 860 mm Hg.Rate this question:
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- 25.
In this diagram, the gas has a fixed pressure of 700 Torr. In the difference between the two columns of mercury measures 100 mm, calculate the current atmospheric pressure.
- A.
800 Torr
- B.
700 Torr
- C.
600 Torr
- D.
100 Torr
Correct Answer
A. 800 TorrExplanation
The atmospheric pressure can be calculated by adding the pressure due to the gas and the pressure due to the mercury column. Since the gas has a fixed pressure of 700 Torr, we only need to consider the pressure due to the mercury column. The pressure due to a column of mercury is directly proportional to the height of the column. In this case, the height of the mercury column is given as 100 mm. Since 1 mm of mercury is equivalent to 1 Torr, the pressure due to the mercury column is 100 Torr. Adding this to the gas pressure of 700 Torr gives a total atmospheric pressure of 800 Torr.Rate this question:
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- 26.
Which of the following would have particles with the greatest average kinetic energy?
- A.
Solid ice at -50oC
- B.
Solid ice at 0oC
- C.
Liquid water at 0oC
- D.
Both solid ice at 0oC and liquid water at 0oC are the same
Correct Answer
D. Both solid ice at 0oC and liquid water at 0oC are the sameExplanation
Both solid ice at 0oC and liquid water at 0oC have the same average kinetic energy because they are at the same temperature. The temperature of a substance is directly proportional to the average kinetic energy of its particles. Since both solid ice and liquid water are at the same temperature, their particles have the same average kinetic energy.Rate this question:
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- 27.
Imagine a cup of hot coffee sitting on a table. In which direction will heat flow?
- A.
The heat will always rise.
- B.
The heat will flow from the coffee to the table.
- C.
The heat will flow from the table to the coffee.
- D.
Heat does not flow.
Correct Answer
B. The heat will flow from the coffee to the table.Explanation
Heat always flows from a higher temperature to a lower temperature. In this case, the coffee is hotter than the table, so the heat will flow from the coffee to the table.Rate this question:
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- 28.
A mole of marbles would fit in a container the size of
- A.
A large aquarium.
- B.
A high school gymnasium.
- C.
Texas.
- D.
The whole world.
Correct Answer
D. The whole world.Explanation
A mole is a unit of measurement in chemistry that represents 6.022 x 10^23 particles. Since a mole of marbles would consist of an incredibly large number of marbles, it would require a container of enormous size to fit them all. The only option that can accommodate this vast quantity is the whole world, as it is the largest possible container.Rate this question:
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- 29.
In which of the following instruments is atmospheric pressure NOT a factor?
- A.
Mercury barometer
- B.
Closed manometer
- C.
Open manometer
- D.
Digital barometer
Correct Answer
B. Closed manometerExplanation
A closed manometer is an instrument used to measure the pressure of a closed system, where the atmospheric pressure does not have any influence or impact. Unlike a mercury barometer or an open manometer, which rely on the balancing of atmospheric pressure with the pressure being measured, a closed manometer is specifically designed to measure the pressure within a closed system, independent of atmospheric pressure. Therefore, atmospheric pressure is not a factor in a closed manometer. A digital barometer, on the other hand, can measure atmospheric pressure.Rate this question:
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- 30.
An ion of sodium would tend to take a charge of
- A.
+1
- B.
+11
- C.
-1
- D.
-2
Correct Answer
A. +1Explanation
An ion of sodium would tend to take a charge of +1 because sodium is an alkali metal with one valence electron. It is more stable and achieves a full outer electron shell by losing this electron, resulting in a positive charge of +1.Rate this question:
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- 31.
Which of the following elements would tend to form an anion?
- A.
Uranium
- B.
Sodium
- C.
Phosphorus
- D.
Argon
Correct Answer
C. PhosphorusExplanation
Phosphorus would tend to form an anion because it is a nonmetal and has a tendency to gain electrons to achieve a stable electron configuration. Anions are formed when atoms gain electrons, resulting in a negative charge. Uranium and sodium are both metals, which typically lose electrons to form cations (positive ions). Argon is a noble gas and is already stable with a full outer electron shell, so it does not tend to form ions.Rate this question:
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- 32.
How many valence electrons would be found in an atom of silicon?
- A.
4
- B.
2
- C.
14
- D.
6
Correct Answer
A. 4Explanation
Silicon is an element with atomic number 14, which means it has 14 electrons. In a neutral atom, the number of electrons is equal to the number of protons. To determine the number of valence electrons, we look at the outermost energy level, which for silicon is the third energy level. The third energy level can hold a maximum of 8 electrons, but silicon only has 4 electrons in this level. Therefore, the correct answer is 4 valence electrons.Rate this question:
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- 33.
How many valence electrons would be found in an atom of chromium?
- A.
1
- B.
2
- C.
6
- D.
5
Correct Answer
A. 1Explanation
Chromium is a transition metal and its atomic number is 24. The number of valence electrons in an atom is determined by the group number it belongs to in the periodic table. Chromium is in group 6, so it has 6 valence electrons. Therefore, the answer 1 is incorrect.Rate this question:
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