Exam 3 - Pre-AP Chemistry - 13 Weeks Exam
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
Gas is the correct answer because in the gaseous state, the molecules are far apart and have high kinetic energy. This allows them to move freely and occupy a larger volume. However, since the molecules are not tightly packed, they can be compressed to a smaller volume by applying pressure. In contrast, in solids and liquids, the molecules are closely packed and have less freedom of movement, making it difficult to compress them to a smaller volume.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 are closely packed together and vibrate in fixed positions. In liquids, the particles are still close together but can move past each other, allowing the liquid to flow. In gases, the particles are far apart and move freely in all directions. Therefore, the correct answer is 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 the pressure from atm to mm Hg, we can use the conversion factor that 1 atm is equal to 760 mm Hg. Therefore, to convert 0.75 atm to mm Hg, we multiply 0.75 by 760. This gives us 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, usually mercury, and the gas pressure is determined by the difference in heights of the liquid in the two arms of the tube. This device is commonly used in various applications, such as in laboratories and industrial processes, to accurately measure and monitor gas pressure.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
To convert atmospheres to kilopascals, you need to multiply the given pressure (1.30 atmospheres) by the conversion factor (101.3 kPa/1 atm). By multiplying 1.30 atmospheres by 101.3 kPa/1 atm, you get 132.49 kPa. Since the question asks for the pressure in kilopascals, you should round the answer to the nearest whole number, which is 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 asks for the number of moles in a given number of atoms of W. To find the number of moles, we divide the given number of atoms by Avogadro's number, which is approximately 6.022 x 10^23. Therefore, 4.8 x 10^25 atoms divided by 6.022 x 10^23 atoms/mol is approximately 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
The molar mass of a substance is the mass of one mole of that substance. In this case, the molar mass of AuCl3 is 303.6 g. This means that if we were to take one mole of AuCl3, it would weigh 303.6 grams.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 can be calculated by adding up the atomic masses of each element: Ba (137.33 g/mol) + N (14.01 g/mol) + O (16.00 g/mol) x 3 = 261.33 g/mol. Dividing the given mass of 432 grams by the molar mass of Ba(NO3)2 gives a result of approximately 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
The elements in period 1 tend to have the highest ionization energy because they have the smallest atomic radii and the highest effective nuclear charge. The small atomic radii result in a stronger attraction between the electrons and the nucleus, making it more difficult to remove an electron. On the other hand, the elements in period 7 tend to have the lowest ionization energy because they have the largest atomic radii and the lowest effective nuclear charge. The larger atomic radii result in a weaker attraction between the electrons and the nucleus, making it easier to remove an electron.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 an element is the energy required to remove one electron from a neutral atom. In this case, the first ionization energy for sodium is 496 kJ/mol. This means that it takes 496 kJ of energy to remove one electron from a sodium atom.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
The octet rule states that atoms tend to gain, lose, or share electrons in order to achieve a stable electron configuration with a full outer shell of eight electrons. In this case, O- has an extra electron, giving it a total of nine electrons. Therefore, it does not have an octet.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 in order to achieve a stable octet, it needs 8 electrons in its outermost energy level. By gaining 3 electrons, nitrogen can fill its outer energy level and achieve a stable configuration similar to that of a noble gas.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
The atom in the diagram has a charge of +1. This is indicated by the positive sign next to the number 1. The plus sign represents a positive charge, while the number 1 indicates the magnitude of the charge.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 farther from the nucleus, resulting in a larger atomic radius. Therefore, 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, or lithium, has the largest atomic radius among the elements in the second period. This is because atomic radius generally decreases across a period from left to right due to increasing nuclear charge. However, Li has the smallest nuclear charge among the elements in the second period, resulting in a larger atomic radius compared to the other elements.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 because atomic radius generally decreases as you move across a period from left to right on the periodic table. This is due to an increase in the number of protons and electrons, which leads to a stronger attraction between the nucleus and the electrons, causing the atomic radius to decrease. Among the given elements, Cl is located on the right side of the periodic table and has the highest atomic number, indicating a smaller atomic radius compared to the others.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 the measure of an atom's ability to attract electrons towards itself in a chemical bond. Cs is a highly electropositive alkali metal with a large atomic size and low effective nuclear charge. These factors contribute to its low electronegativity value, indicating that Cs is less likely to attract electrons compared to the other elements listed (At, Ca, and F).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 has the highest electronegativity value among the given elements. Electronegativity is a measure of an atom's ability to attract electrons towards itself in a chemical bond. Fluorine, being the most electronegative element on the periodic table, has a strong attraction for electrons, making it highly reactive and capable of forming strong bonds with other elements. This high electronegativity 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
C. Increase in the number of protonsExplanation
As the atomic number increases within a group in the periodic table, the number of protons in the nucleus also increases. This increase in the number of protons leads to a stronger attraction between the protons in the nucleus and the electrons in the outermost energy level. As a result, it becomes more difficult to remove an electron from the atom, leading to an increase in ionization energy. Therefore, the correct answer is that an increase in the number of protons contributes to the decrease in ionization energy within a group.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 the correct answer because it represents the mass of one atom of argon. The other options do not accurately represent the mass of one atom of argon.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 (such as atoms or molecules) that are in constant motion. It also states that these particles undergo completely elastic collisions with each other and that they are constantly moving, except at absolute zero. However, the theory does not make any statement about the creation or destruction of atoms in a chemical reaction. Therefore, the statement "Atoms cannot be created or destroyed in a chemical reaction" is NOT a part of the Kinetic-Molecular Theory.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 statement "The average distance between particle collisions is called mean free path" is true. In a gas or liquid, particles are constantly moving and colliding with each other. The mean free path is the average distance that a particle travels between collisions with other particles. It is a measure of how crowded or dense the particles are in a given space.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 atmospheric pressure and the pressure of the contained gas. Since the height difference is 100 mm and the atmospheric pressure is 760 mm Hg, the pressure of the contained gas would 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
Based on the information given, the gas has a fixed pressure of 700 Torr. The difference between the two columns of mercury measures 100 mm. The height of a column of mercury is directly proportional to the atmospheric pressure. Therefore, if the difference in height is 100 mm, it means that the atmospheric pressure is 100 Torr higher than the pressure of the gas. Adding this difference to the fixed pressure of the gas (700 Torr) gives us 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
At 0oC, both solid ice and liquid water are at the same temperature. However, the kinetic energy of the particles in a substance is directly related to its temperature. Since the temperature is the same for both solid ice and liquid water, they would 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 an object with a higher temperature to an object with a lower temperature. In this scenario, the coffee is hotter than the table, so the heat will flow from the coffee to the table in order to equalize their temperatures.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 used in chemistry to represent a large number (6.022 x 10^23) of particles. In this context, a mole of marbles would refer to a collection of marbles that is equal to this enormous number. Since the number is so large, it would require a container that is as big as the entire world to fit all the marbles. Thus, the correct answer is "the whole world."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 gas in a closed system. Unlike a mercury barometer or an open manometer, it does not rely on atmospheric pressure as a factor in its measurement. Instead, it measures the pressure difference between the gas being measured and a reference gas. Therefore, atmospheric pressure does not affect the readings of a closed manometer.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 belongs to Group 1 in the periodic table, which means it has one valence electron. Sodium is highly reactive and tends to lose this valence electron to achieve a stable electron configuration, 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 is a metal and tends to lose electrons to form cations, while sodium is also a metal and has a tendency to lose electrons. 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 in Group 14 of the periodic table, meaning it has 4 valence electrons. Valence electrons are the electrons in the outermost energy level of an atom and are responsible for the atom's chemical properties. Since silicon is in Group 14, it has 4 valence electrons in its outermost energy level.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
The correct answer is 6. Chromium is a transition metal and is located in Group 6 of the periodic table. It has an atomic number of 24, which means it has 24 electrons. To determine the number of valence electrons, we look at the electron configuration of chromium, which is [Ar] 3d5 4s1. The 4s and 3d orbitals are the valence orbitals, and in this case, there are a total of 6 valence electrons.Rate this question:
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