[User]
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Based on the strength of the intermolecular forces in each substance, estimate from greatest to smallest the vapor pressures of each substance in liquid state at the same temperature.

A. propane > ethanal > ethene > methanol
B. ethene > propane > ethanal > methanol
C. ethanal > methanol > ethene > propane
D. methanol > ethanal > propane > ethene

[Assistant] B


[User]
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When in liquid state, which two substances are most likely to be miscible with water?

A. propane and ethene
B. methanol and propane
C. ethene and ethanal
D. methanol and ethanal

[Assistant] D


[User]
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Between propane and ethene, which will likely have the higher boiling point and why?

A. propane, because it has a greater molar mass
B. propane, because it has a more polarizable electron cloud
C. ethene, because of the double bond
D. ethene, because it is smaller in size

[Assistant] B


[User]
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The graph below shows the amount of potential energy between two hydrogen atoms as the distance between them changes. At which point in the graph would a molecule of $H_2$ be the most stable?

A. Point A
B. Point B
C. Point C
D. Point D

[Assistant] C


[User]
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Two alloys are shown in the diagrams below—bronze, and steel. Which of the following correctly describes the malleability of both alloys compared to their primary metals?

A. Bronze's malleability would be comparable to that of copper, but steel's malleability would be significantly lower than that of iron.
B. Bronze's malleability would be significantly higher than that of copper, but steel's malleability would be comparable to that of iron.
C. Both bronze and steel would have malleability values similar to those of their primary metals.
D. Both bronze and steel would have malleability values greater than those of their primary metals.

[Assistant] C


[User]
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The following diagram shows the relative atomic sizes of three different elements from the same period. Which of the following statements must be true?

A. The effective nuclear charge would be the greatest in element X.
B. The first ionization energy will be greatest in element X.
C. The electron shielding effect will be greatest in element Z.
D. The electronegativity value will be greatest in element Z.

[Assistant] D


[User]
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Two half-cells are set up as follows:

Half-Cell A: Strip of Cu(s) in $CuNO_3(aq)$

Half-Cell B: Strip of Zn(s) in $Zn(NO_3)_2(aq)$

When the cells are connected according to the following diagram, the following reaction occurs. Correctly identify the anode and cathode in this reaction as well as where oxidation and reduction are taking place.
 A. Cu is the anode where oxidation occurs, and Zn is the cathode where reduction occurs.
 B. Cu is the anode where reduction occurs, and Zn is the cathode where oxidation occurs.  C. Zn is the anode where oxidation occurs, and Cu is the cathode where reduction occurs.
 D. Zn is the anode where reduction occurs, and Cu is the cathode where oxidation occurs.

[Assistant] C


[User]
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Two half-cells are set up as follows:

Half-Cell A: Strip of Cu(s) in $CuNO_3(aq)$

Half-Cell B: Strip of Zn(s) in $Zn(NO_3)_2(aq)$

When the cells are connected according to the following diagram, the following reaction occurs. How many moles of electrons must be transferred to create 127 g of copper?

A. 1 mole of electrons
B. 2 moles of electrons
C. 3 moles of electrons
D. 4 moles of electrons

[Assistant] B


[User]
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Two half-cells are set up as follows:

Half-Cell A: Strip of Cu(s) in $CuNO_3(aq)$

Half-Cell B: Strip of Zn(s) in $Zn(NO_3)_2(aq)$

When the cells are connected according to the following diagram, the following reaction occurs. If the $Cu^+ + e^- → Cu(s)$ half reaction has a standard reduction potential of +0.52 V, what is the standard reduction potential for the $Zn^{2+} + 2e^- → Zn(s)$ half reaction?

A. +0.76 V
B. -0.76 V
C. +0.24 V
D. -0.24 V

[Assistant] B


[User]
<image>
Two half-cells are set up as follows:

Half-Cell A: Strip of Cu(s) in $CuNO_3(aq)$

Half-Cell B: Strip of Zn(s) in $Zn(NO_3)_2(aq)$

When the cells are connected according to the following diagram, the following reaction occurs. As the reaction progresses, what will happen to the overall voltage of the cell?

A. It will increase as [$Zn^{2+}$] increases.
B. It will increase as [$Cu^{+}$] increases.
C. It will decrease as [$Zn^{2+}$] increases.
D. The voltage will remain constant.

[Assistant] C


[User]
<image>
Two half-cells are set up as follows:

Half-Cell A: Strip of Cu(s) in $CuNO_3(aq)$

Half-Cell B: Strip of Zn(s) in $Zn(NO_3)_2(aq)$

When the cells are connected according to the following diagram, the following reaction occurs. What will happen in the salt bridge as the reaction progresses?

A. The Na+ ions will flow to the Cu/Cu+ half-cell.
B. The Br- ions will flow to the Cu/Cu+ half-cell.
C. Electrons will transfer from the Cu/Cu+ half-cell to the Zn/Zn2+ half-cell.
D. Electrons will transfer from the Zn/Zn2+ half-cell to the Cu/Cu+ half-cell.

[Assistant] A


[User]
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A solution of carbonic acid, $H_2CO_3$, is titrated with sodium hydroxide, NaOH. The following graph is produced. In addition to $OH^-$, what species are present in the solution during section III of the graph?

A. $H_2CO_3$, $HCO_3^-$, and $CO_3^{2-}$
B. $H_2CO_3$ and $HCO_3^-$
C. $HCO_3^-$ and $CO_3^{2-}$
D. $H_2CO_3$ and $CO_3^{2-}$

[Assistant] C


[User]
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A solution of carbonic acid, H2CO3, is titrated with sodium hydroxide, NaOH. The following graph is produced. What is the magnitude of the first dissociation constant?

A. 10e-2
B. 10e-4
C. 10e-6
D. 10e-8

[Assistant] C


[User]
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A solution of carbonic acid, H2CO3, is titrated with sodium hydroxide, NaOH. The following graph is produced. If the concentration of the sodium hydroxide is increased prior to repeating the titration, what effect, if any, would that have on the graph?

A. The graph would not change at all.
B. The pH values at the equivalence points would increase.
C. The equivalence points would be reached with less volume of NaOH added.
D. The slope of the equivalence points would decrease.

[Assistant] C


[User]
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Two solutions of potassium carbonate and sodium chloride are mixed together, and the particulate representation below shows what is present after the reaction has gone to completion. Which of the two original solutions is the limiting reagent and why?

A. The potassium carbonate, because of the polyatomic anion
B. The potassium carbonate, because there is no carbonate left after the reaction
C. The calcium chloride, because there is an excess of calcium ions post-reaction
D. The calcium chloride, because the component ions are smaller than those in potassium carbonate

[Assistant] B


[User]
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 The structure of two oxoacids is shown below. Which would be a stronger acid, and why?

A. HOCl, because the H–O bond is weaker than in HOF as chlorine is larger than fluorine
B. HOCl, because the H–O bond is stronger than in HOF as chlorine has a higher electronegativity than fluorine
C. HOF, because the H–O bond is stronger than in HOCl as fluorine has a higher electronegativity than chlorine
D. HOF, because the H–O bond is weaker than in HOCl as fluorine is smaller than chlorine

[Assistant] D


[User]
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The following diagrams show the Lewis structures of four different molecules. Which molecule would travel the farthest in a paper chromatography experiment using a polar solvent?

A. Methanol
B. Pentane
C. Acetone
D. Ether

[Assistant] A


[User]
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Four different acids are added to beakers of water, and the following diagrams represent the species present in each solution at equilibrium. Which acid has the highest pH?

A. Acid 1
B. Acid 2
C. Acid 3
D. Acid 4

[Assistant] C


[User]
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Lewis diagrams for the nitrate and nitrite ions are shown below. Choose the statement that correctly describes the relationship between the two ions in terms of bond length and bond energy.

A. Nitrite has longer and stronger bonds than nitrate.
B. Nitrite has longer and weaker bonds than nitrate.
C. Nitrite has shorter and stronger bonds than nitrate.
D. Nitrite has shorter and weaker bonds than nitrate.

[Assistant] C


[User]
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$NO_2$ gas is placed in a sealed, evacuated container and allowed to decompose via the following equation:

$2NO_2(g) ↔ 2NO(g) + O_2(g)$

The graph below indicates the change in concentration for each species over time. What is happening to the rate of the forward reaction at t = 60 s?

A. It is increasing.
B. It is decreasing.
C. It is remaining constant.
D. It is zero.

[Assistant] C


[User]
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$NO_2$ gas is placed in a sealed, evacuated container and allowed to decompose via the following equation:

$2NO_2(g) ↔ 2NO(g) + O_2(g)$

The graph below indicates the change in concentration for each species over time. As the reaction progresses, what happens to the value of the equilibrium constant Kp if the temperature remains constant?

A. It stays constant.
B. It increases exponentially.
C. It increases linearly.
D. It decreases exponentially.

[Assistant] A


[User]
<image>
$NO_2$ gas is placed in a sealed, evacuated container and allowed to decompose via the following equation:

$2NO_2(g) ↔ 2NO(g) + O_2(g)$

The graph below indicates the change in concentration for each species over time. What would happen to the slope of the $NO_2$ line if additional $O_2$ were injected into the container?

A. It would increase, then level off.
B. It would decrease, then level off.
C. It would remain constant.
D. It would increase, then decrease.

[Assistant] A


[User]
<image>
$NO_2$ gas is placed in a sealed, evacuated container and allowed to decompose via the following equation:

$2NO_2(g) ↔ 2NO(g) + O_2(g)$

The graph below indicates the change in concentration for each species over time. Using the graph, how could you determine the instantaneous rate of disappearance of $NO_2$ at t = 30 s?

A. By determining the area under the graph at t = 30 s
B. By taking the slope of a line tangent to the $NO_2$curve at t = 30 s
C. By using the values at t = 30 s and plugging them into the Kp expression
D. By measuring the overall gas pressure in the container at t = 30 s.

[Assistant] B


[User]
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The reaction shown in the following diagram is accompanied by a large increase in temperature. If all molecules shown are in their gaseous state, which statement accurately describes the reaction?

A. It is an exothermic reaction in which entropy increases.
B. It is an exothermic reaction in which entropy decreases.
C. It is an endothermic reaction in which entropy increases.
D. It is an endothermic reaction in which entropy decreases.

[Assistant] A


[User]
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The contents in the three containers on the left in the diagram above are transferred to the container on the right. The volumes of the original containers are exactly the values indicated. The pressure in the first three containers is 1.0 atm. What is the pressure in the container on the right?

A. 3.0 atm
B. 4.0 atm
C. 1.1 atm
D. 0.50 atm

[Assistant] C


[User]
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The diagram above shows the structure of molecules of CS2 and COS. The boiling point of COS is 223 K, and the boiling point of CS2 is 319 K. Which of the following is the best explanation of why the boiling point of CS2 is higher?

A. The molar mass of CS2 is greater.
B. COS has weaker covalent bonds than CS2.
C. Only CS2 can form intermolecular dipole-dipole forces.
D. COS has stronger intermolecular forces because it is polar and CS2 is not.

[Assistant] A


[User]
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Which of the following best explains why the boiling point of 2-propanol is lower than the other two compounds in the diagram and table above?

A. Larger molecules get tangled and cannot escape each other.
B. It has weaker hydrogen bonds.
C. It is the lightest of the three.
D. It is a more symmetrical molecule.

[Assistant] C


[User]
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The Dumas method is a procedure for determining the molar mass of a gas. In this procedure the mass of a gas is divided by the moles of gas determined from the ideal gas equation (n = PV/RT). The molar masses of some compounds, such as acetic acid, illustrated above, show significant deviations from the “correct” values. Why does the presence of dimers as illustrated make it unlikely to obtain an accurate molar mass of acids, such as acetic acid?

A. Acetic acid, like all acids, will lose a hydrogen ion, so the molar mass is that of the acetate ion, which is less than that of acetic acid.
B. Acetic acid is a liquid at room temperature, and its boiling point is too high to get accurate results.
C. Acids are too reactive to give accurate results.
D. The presence of strong intermolecular forces (hydrogen bonding) makes the gas nonideal; therefore the ideal gas law is not applicable.

[Assistant] D


[User]
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Which of the labeled arrows in the diagram above represents the strongest intermolecular force?

A. A
B. B
C. C
D. D

[Assistant] B


[User]
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pH versus volume of titrant added
The diagram above represents the idealized titration curve for the reaction of pure sodium carbonate, Na2CO3, with a strong acid such as hydrochloric acid, HCl. E and F represent the pH at the endpoints corresponding to the formation of HCO3- and H2CO3, respectively. G and H correspond to the quantity of acid required to reach the endpoints.
A trial run used a sample of pure sodium carbonate. How does the volume of acid necessary to reach G from 0 compare to the volume of acid necessary to get from G to H?

A. They are the same.
B. It takes more to reach point G.
C. It takes more to get from G to H.
D. It is impossible to determine

[Assistant] A


[User]
<image>
pH versus volume of titrant added
The diagram above represents the idealized titration curve for the reaction of pure sodium carbonate, Na2CO3, with a strong acid such as hydrochloric acid, HCl. E and F represent the pH at the endpoints corresponding to the formation of HCO3- and H2CO3, respectively. G and H correspond to the quantity of acid required to reach the endpoints.
The analysis of a sample contaminated with NaHCO3 gave slightly different results. How does the volume of acid necessary to reach G from 0 compare to the volume of acid necessary to get from G to H for the second sample?

A. It takes more to get from G to H.
B. It takes more to reach point G.
C. They are the same.
D. It is impossible to determine.

[Assistant] C


[User]
<image>
pH versus volume of titrant added
The diagram above represents the idealized titration curve for the reaction of pure sodium carbonate, Na2CO3, with a strong acid such as hydrochloric acid, HCl. E and F represent the pH at the endpoints corresponding to the formation of HCO3- and H2CO3, respectively. G and H correspond to the quantity of acid required to reach the endpoints.
How could a student determine if there was a strong acid or a strong base contaminant in the original sample?

A. The presence of an acid contaminant would require less acid to reach H from G than to reach G from 0.
B. The presence of a base contaminant would require less acid to reach G from 0 than to reach F from G.
C. The presence of a base contaminant would require more acid to reach G from 0 than to reach F from G.
D. It is impossible to determine.

[Assistant] C


[User]
<image>
pH versus volume of titrant added
The diagram above represents the idealized titration curve for the reaction of pure sodium carbonate, Na2CO3, with a strong acid such as hydrochloric acid, HCl. E and F represent the pH at the endpoints corresponding to the formation of HCO3- and H2CO3, respectively. G and H correspond to the quantity of acid required to reach the endpoints.
In addition to water, what are the predominant species in solution at F?

A. $\ch{Na2CO3}$ and $\ch{HCl}$
B. $\ch{Na+}$, $\ch{Cl-}$, and $\ch{H2CO3}$
C. $\ch{HCO3-}$ and $\ch{H+}$
D.$ \ch{Na+}$, $\ch{Cl-}$, $\ch{H+}$, and $\ch{CO3^{2-}}$

[Assistant] B


[User]
<image>
pH versus volume of titrant added
The diagram above represents the idealized titration curve for the reaction of pure sodium carbonate, Na2CO3, with a strong acid such as hydrochloric acid, HCl. E and F represent the pH at the endpoints corresponding to the formation of HCO3- and H2CO3, respectively. G and H correspond to the quantity of acid required to reach the endpoints.
In addition to water, what are the predominant species in solution at F?

At what point on the graph for the titration of pure sodium carbonate is the pH =\ch{ pK_{a2}} for carbonic acid?

A. At point G
B. Halfway between the start and point G
C. At point H
D. Halfway between points G and H

[Assistant] D


[User]
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What is the reason that the lightest member of Group 15 does not follow the trend of the other members, which show that the boiling point decreases with decreasing atomic mass of the Group 15 element?
The graph shows the variation of boiling point with Group number for the hydrogen compounds of the four lightest members of Group 15 on the periodic table (NH3, PH3, AsH3 and SbH3).

A. Ionic bonds
B. Hybrid orbitals
C. Resonance structures
D. Hydrogen bonding


[User]
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A dimer consists of two closely associated molecules. In the gas phase, acetic acid tends to form dimers as illustrated on the left in the above diagram. Acetyl chloride, on the right in the above diagram, is not very efficient in forming dimers. Why is acetic acid better able to form dimers than acetyl chloride?

A. The molecular mass of acetyl chloride is higher than that of acetic acid making it harder for the acetyl chloride to form dimers.
B. It is easier to form a covalent bond between acetic acid molecules than between acetyl chloride molecules.
C. Acetic acid can form strong hydrogen bonds but acetyl chloride can only form weaker dipole-dipole attractions.
D. Acetic acid is an acidic compound but acetyl chloride is a neutral compound.

[Assistant] C


[User]
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Two compounds with the formula C2H2Cl2 appear in the above diagram. These two compounds are isomers. The molecules are planar and have the approximate structures shown in the diagram. The boiling point of trans-1, 2-dichloroethene is 47.5°C and the boiling point of cis-1,2-dichloroethene is 60.3°C. Which of the following best explains why cis-1,2-dichloroethene has a higher boiling point than its isomer, trans-1, 2-dichloroethene?

A. The higher boiling isomer is more polar than the other isomer.
B. The higher boiling isomer is better able to form hydrogen bonds than the other isomer.
C. The higher boiling isomer has a greater molar mass.
D. The higher boiling isomer has greater London dispersion forces than the other isomer.

[Assistant] A


[User]
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Use the following information on the bases in the following diagram to answer questions.
https://img.crackap.com/ap/chemistry/a5/Image00543.jpg

Ammonia is only present as a reference. Questions only refer to the other three bases.
https://img.crackap.com/ap/chemistry/a5/Image00544.jpg

All the bases in the diagram behave as Brønsted-Lowry bases in the same way; in each case, they accept a hydrogen ion to the same atom. How is this acceptance of a hydrogen ion accomplished?

A. A hydrogen ion attaches to the lone pair on the nitrogen atom.
B. The hydroxide ion reacts with the hydrogen ion to form water.
C. The hydrogen ion forms a hydrogen bond to the base.
D. The hydrogen ion combines with a hydrogen atom from the base to form H2 gas

[Assistant] A


[User]
<image>
Use the following information on the bases in the following diagram to answer questions.
https://img.crackap.com/ap/chemistry/a5/Image00543.jpg

Ammonia is only present as a reference. Questions only refer to the other three bases.
https://img.crackap.com/ap/chemistry/a5/Image00544.jpg

Which of the following explains why the pH of a hydroxylamine solution is lower than any of the other solutions?

A. The $-OH$ is capable of donating a hydrogen ion, which will lower the pH.
B. The presence of carbon makes the bases less stable.
C. The presence of the very electronegative oxygen inhibits the nitrogen atom from donating its electron pair.
D. There is insufficient information to explain this observation.

[Assistant] C


[User]
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Which of the compounds in the above diagram is capable of participating in hydrogen bonding?

A. $C_3H_9N$
B. $CH_3F$
C. $C_2H_6O$
D. $C_4H_11$

[Assistant] D


[User]
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Ammonia is the best-known nitrogen-hydrogen compound; however, there are a number of other nitrogen-hydrogen compounds, three of which are in the above diagram. Which of these has the longest average N-N bond length?

A. $N_2H_2$
B. $N_3H_3$
C. $N_4H_4$
D. They are all the same.

[Assistant] C


[User]
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Use the information on the acids in the following diagram to answer questions.

Sample solutions of each of the three acids were titrated with 0.10 M sodium hydroxide, NaOH. Each of the acid solutions had a concentration of 0.10 M. Which of the acid titrations had the highest pH at the endpoint?

A. Formic acid
B. Benzoic acid
C. Chloroacetic acid
D. They all had a pH of 7 at the endpoint.

[Assistant] B


[User]
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Use the information on the acids in the following diagram to answer questions.

A student prepares three buffer solutions. Each solution is 1.0 M in one of the acids in the table and 1.0 M in its corresponding sodium salt. Which of the solutions has the greatest buffer capacity with respect to added NaOH and why?

A. The benzoic acid buffer because it is the strongest acid.
B. The chloroacetic acid buffer because it is the strongest acid.
C. The formic acid buffer because it donate both of its hydrogen atoms.
D. All are the same.

[Assistant] D


[User]
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Cyclopropane, pictured above, is a relatively unstable compound. As seen in the diagram, the carbon atoms form the corners of an equilateral triangle and each carbon atom has two hydrogen atoms attached to complete an octet of electrons around the carbon atoms. Based upon this structure, why is cyclopropane a relatively unstable compound?

A. Hydrocarbon compounds are relatively unstable in general.
B. Compounds that have identical atoms bonded to each other are relatively unstable.
C. The bonds do not match the angles.
D. There is no resonance to stabilize the compound.

[Assistant] C


[User]
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Refer to the following information.

$N_2O_4(g)\rightleftarrows 2NO_2(g)$

$N_2O_4(g)$ decomposes into $NO_2(g)$ according to the equation above. A pure sample of $N_2O_4(g)$ is placed into a rigid, evacuated, 0.500 L container. The initial pressure of the $N_2O_4(g)$ is 760 atm. The temperature is held constant until the $N_2O_4(g)$ reaches equilibrium with its decomposition products. The figure below shows how the pressure of the system changes while reaching equilibrium. Why does the pressure rise in this experiment?

A. The intermolecular attractions inside the container decrease, so the molecules strike the walls more frequently.
B. The intermolecular attractions inside the container increase, which increases the force as molecules collide with the walls of the container.
C. The average kinetic energy increases as the reaction continues.
D. The number of particles striking the container walls per unit time increases.

[Assistant] D


[User]
<image>
Refer to the following information.

$N_2O_4(g)\rightleftarrows 2NO_2(g)$

$N_2O_4(g)$ decomposes into $NO_2(g)$ according to the equation above. A pure sample of $N_2O_4(g)$ is placed into a rigid, evacuated, 0.500 L container. The initial pressure of the $N_2O_4(g)$ is 760 atm. The temperature is held constant until the $N_2O_4(g)$ reaches equilibrium with its decomposition products. The figure below shows how the pressure of the system changes while reaching equilibrium. The figure above gives us information about all the following except

A. the activation energy
B. the reaction rate
C. the position of equilibrium
D. the order of reaction

[Assistant] A


[User]
<image>
Refer to the following information.

$N_2O_4(g)\rightleftarrows 2NO_2(g)$

$N_2O_4(g)$ decomposes into $NO_2(g)$ according to the equation above. A pure sample of $N_2O_4(g)$ is placed into a rigid, evacuated, 0.500 L container. The initial pressure of the $N_2O_4(g)$ is 760 atm. The temperature is held constant until the $N_2O_4(g)$ reaches equilibrium with its decomposition products. The figure below shows how the pressure of the system changes while reaching equilibrium. By how much will the equilibrium pressure increase if this reaction goes to completion?

A. 760 torr
B. 900 torr
C. 634 torr
D. 886 torr

[Assistant] C


[User]
<image>
Refer to the following information.

$N_2O_4(g)\rightleftarrows 2NO_2(g)$

$N_2O_4(g)$ decomposes into $NO_2(g)$ according to the equation above. A pure sample of $N_2O_4(g)$ is placed into a rigid, evacuated, 0.500 L container. The initial pressure of the $N_2O_4(g)$ is 760 atm. The temperature is held constant until the $N_2O_4(g)$ reaches equilibrium with its decomposition products. The figure below shows how the pressure of the system changes while reaching equilibrium. What can be said about the equilibrium constant, Kp, for this reaction?

A. $K_p$ > 1
B. $K_p$< 1
C. $K_p$= 1
D. The data do not allow us to estimate the value of $K_p$.

[Assistant] B


[User]
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Refer to the following information.

This formation equation for the reaction synthesizing RbBr(s) can be separated into a series of steps. Which of the steps in the table above are endothermic?

A. ΔH°(1) and ΔH°(2) only
B. ΔH°(1), ΔH°(2), and ΔH°(3) only
C. ΔH°(3) only
D. ΔH°(3) and ΔH°(4) only

[Assistant] B


[User]
<image>
Refer to the following information.

This formation equation for the reaction synthesizing RbBr(s) can be separated into a series of steps. If this reaction goes to completion, producing RbBr from the reactants, and if you use the overall chemical equation to estimate the entropy change for this process, which of the following statements is correct?

A. The reaction is favorable and driven by the enthalpy change since the entropy decreases in this process.
B. The reaction is unfavorable since the entropy change is a large negative value.
C. The reaction is favorable and driven by both enthalpy and entropy changes.
D. The reaction is unfavorable because of the enthalpy and entropy changes.

[Assistant] A


[User]
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n-pentane ($C_5H_{12}$ or $CH_3CH_2CH_2CH_2CH_3$) and 2,2-dimethylpropane ($C_5H_{12}$ or $(CH_3)_4C$), shown above as space-filling models, each have the same number of carbon and hydrogen atoms but the atoms are arranged differently. n-pentane boils at 36.1 °C, and 2,2-dimethylpropane boils at 9.5 °C. Which statement best explains these data?

A. The long chains of n-pentane make it more difficult for them to reach the liquid surface and vaporize.
B. The long chains of n-pentane provide more sites for London attractive forces for neighboring molecules to have an effect on each other.
C. The compact structure of the 2,2-dimethylpropane directs the attractive forces internally in the molecule.
D. The bonds in the n-pentane are weaker, allowing small parts of the molecule to vaporize easily.

[Assistant] B


[User]
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Refer to the following information.

Four different acid solutions of 0.0100 M are prepared, and their pH values are recorded on a laptop computer. One of the solutions contains more than just an acid. At the point designated as "add," all four solutions are diluted with an equal volume of water. The bottom line represents solution 1, and the top line represents solution 4. Which of the four acids is best described as a strong acid?

A. Solution 1
B. Solution 2
C. Solution 3
D. Solution 4

[Assistant] A


[User]
<image>
Refer to the following information.

Four different acid solutions of 0.0100 M are prepared, and their pH values are recorded on a laptop computer. One of the solutions contains more than just an acid. At the point designated as "add," all four solutions are diluted with an equal volume of water. The bottom line represents solution 1, and the top line represents solution 4. Which acid(s) will require the most 0.0050 M NaOH to neutralize 25.0 mL of a 0.010 M solution of the acid?

A. Solution 1
B. Solution 2
C. Solution 3
D. They will all require the same volume of NaOH.

[Assistant] D


[User]
<image>
Refer to the following information.

Four different acid solutions are prepared, and their pH values are determined and tabulated below. Using the data in the table above, which is the weakest acid?

A. Acid 1
B. Acid 2
C. Acid 3
D. Acid 4

[Assistant] D


[User]
<image>
Refer to the following information.

Four different acid solutions are prepared, and their pH values are determined and tabulated below. Which of the four acids is best described as a strong acid?

A. Acid 1
B. Acid 2
C. Acid 3
D. Acid 4

[Assistant] B


[User]
<image>
Refer to the following information.

Four different acid solutions are prepared, and their pH values are determined and tabulated below. Which of the following operations will produce an effective buffer solution?

A. 50.0 mL of 0.010 M acid 3 mixed with 50.0 mL of 0.010 M acid 2
B. 50.0 mL of 0.010 M acid 2 mixed with 25.0 mL of 0.010 M NaOH
C. 50.0 mL of 0.0050 M acid 4 mixed with 0.25 mL of 0.0050 M NaOH
D. 50.0 mL of 0.0010 M acid 2 mixed with 55.0 mL of 0.0010 M NaOH

[Assistant] B


[User]
<image>
Refer to the following information.

Four different acid solutions are prepared, and their pH values are determined and tabulated below. Each of the acids were titrated with NaOH to the end point. The end point pH values are shown on the last line of the table. The end point pH values

A. suggest that acid 3 is strong and all the rest are weak
B. suggest that all the acids are weak
C. suggest that acid 1 is most likely polyprotic
D. suggest serious problems with the pH meter

[Assistant] C


[User]
<image>
The graph above shows the distribution of kinetic energies of a system containing a large number of SO2 molecules at 300 K. Which letter shows the average kinetic energy of this system?

A. A
B. B
C. C
D. D

[Assistant] C


[User]
<image>
Three 1-liter flasks are connected to a 3-liter flask by valves. The 3-liter flask is evacuated to start and the entire system is at 585 K. The first flask contains oxygen, the second hydrogen, and the third nitrogen. The pressure of hydrogen is 1.65 atm. The amounts of gas molecules are proportional to their representations in the flasks. If valve 2 is opened first and then the rest of the valves are opened, what will the pressure be after the first valve is opened and after they all are opened? Assume the connections have negligible volume.

Valve 2 Opened   All Valves Opened

A. 1.0 atm   0.5 atm
B. 0.41 atm   0.82 atm
C. 0.81 atm   1.65 atm
D. 2.0 atm   1.0 atm

[Assistant] B


[User]
<image>
A mass spectrum of a naturally occurring sample of an element is shown above. What is the element?

A. Ca
B. Ne
C. K
D. Not enough information is provided.

[Assistant] B


[User]
<image>
Refer to the titration curve below, which is of a weak base titrated with a strong acid. The pH was measured with a pH meter after small volumes of 0.125 M HCl were added to 25.0 mL of a weak base. Data from that experiment are shown in the above graph. Which of the following describes the base that is being titrated?

A. The base is dibasic since two end points are observed.
B. The concentration of the base is exactly 0.125 M.
C. The concentration of the base is slightly more than 0.125 M.
D. The concentration of the base is slightly less than 0.125 M.

[Assistant] D


[User]
<image>
Refer to the titration curve below, which is of a weak base titrated with a strong acid. The pH was measured with a pH meter after small volumes of 0.125 M HCl were added to 25.0 mL of a weak base. Data from that experiment are shown in the above graph. Between which two points on the titration curve can the solution be described as a buffer?

A. None, it is impossible for a titration solution to also be a buffer solution.
B. A to F
C. A to D
D. D to F

[Assistant] C


[User]
<image>
Refer to the titration curve below, which is of a weak base titrated with a strong acid. The pH was measured with a pH meter after small volumes of 0.125 M HCl were added to 25.0 mL of a weak base. Data from that experiment are shown in the above graph. For the best results with a visual indicator (one that changes color), what will optimize the results?

A. Add the indicator two drops before the end point.
B. Choose an indicator that has a pK that is close to the end point pH.
C. Choose an indicator that has complementary colors.
D. Choose a polyprotic indicator.

[Assistant] B


[User]
<image>
Refer to the titration curve below, which is of a weak base titrated with a strong acid. The pH was measured with a pH meter after small volumes of 0.125 M HCl were added to 25.0 mL of a weak base. Data from that experiment are shown in the above graph. If the student uses a pH indicator that changes color from pH 6 to 8, which statement best characterizes the expected observations?

A. The observed color change will be distinct, and the calculated molarity of the base will be accurate.
B. The color will change slowly, and the end point volume will be low.
C. The color will change slowly, and the calculated molarity of the base will be low.
D. The observed color change will be distinct, but the calculated molarity of the base will be high.

[Assistant] B


[User]
<image>
Refer to the titration curve below, which is of a weak base titrated with a strong acid. The pH was measured with a pH meter after small volumes of 0.125 M HCl were added to 25.0 mL of a weak base. Data from that experiment are shown in the above graph. Which arrow points to the place on the curve where pH = pKaof the conjugate acid of the base?

A. A
B. E
C. C
D. F

[Assistant] C


[User]
<image>
In the diagram above, which labeled arrow is pointing toward a covalent bond and which is pointing toward a hydrogen bond?

Covalent Bond   Hydrogen Bond

A. 1   2
B. 2   1
C. 3   4
D. 4   3

[Assistant] D


[User]
<image>
Morphine, $C_{17}H_{19}NO_3$ (shown above), has a $K_b = 8.0 × 10^{-7}$. If a 0.00100 M solution of morphine is prepared, the expected pH will be in which one of the following pH ranges?

A. 2 to 4
B. 4 to 6
C. 8 to 10
D. 10 to 12

[Assistant] C


[User]
<image>
The volume of a gas is charted over time, giving the above results. Which of the following options provides a possibel explinatin of what was happening to the gas during each phase of the graph?

A. During phase I, the temperature decreased while the pressure increased. During phase II, the temperature was held constant as the pressure decreased.
B. During phase I, the temperature increased while the pressure was held constant. During phase II, the temperature and pressure both decreased.
C. During phase I, the temperature was held constant while the pressure increased. During phase II, the temperature and pressure both decreased.
D. During phase I, the temperature and pressure both increased. During phase II, the temperature was held constant while the pressure decreased.

[Assistant] B


[User]
<image>
The above experiment was performed several times, and the data was gathered as shown in the figure. What is the rate law for this reaction?

A. rate = k[NO][Br$_2$]$^2$
B. rate = k[NO]$^2$[Br$_2$]$^2$
C. rate = k[NO][Br$_2$]
D. rate = k[NO]$^2$[Br$_2$]

[Assistant] D


[User]
<image>
Regarding reaction II, to achieve the products present in the above diagram how many moles of each reactant must be present prior to the reaction?

A. 1.0 mol of CH$_4$ and 2.0 mol of H$_2$O
B. 2.0 mol of CH$_4$ and 2.0 mol of H$_2$O
C. 2.0 mol of CH$_4$ and 3.0 mol of H$_2$O
D. 3.0 mol of CH$_4$ and 2.0 mol of H$_2$O

[Assistant] C


[User]
<image>
Identify the three gases represented on the Maxwell-Boltzmann diagram above. Assume all gases are at the same temperature.

A. I \( \mathrm{H_2} \) II \( \mathrm{N_2} \) III \( \mathrm{F_2} \)
B. I \( \mathrm{H_2} \) II \( \mathrm{F_2} \) III \( \mathrm{N_2} \)
C. I \( \mathrm{F_2} \) II \( \mathrm{N_2} \) III \( \mathrm{H_2} \)
D. I \( \mathrm{N_2} \) II \( \mathrm{F_2} \) III \( \mathrm{H_2} \)

[Assistant] C


[User]
<image>
The above diagrams shows the decomposition of hydrogen peroxide in a sealed container in the presence of a catalyst. What is the overall order for the reaction?

A. Zero order
B. First order
C. Second order
D. Third order

[Assistant] B


[User]
<image>
One of the resonance structures for the nitrite ion is shown above. What is the formal charge on each atom?

A. O$_x$ -1; N +2; O$_y$ -1
B. O$_x$ +1; N -1; O$_y$ 0
C. O$_x$ 0; N 0 ; O$_y$ -1
D.O$_x$ -1; N 0 ; O$_y$ 0

[Assistant] D


[User]
<image>
The following diagram supports which of the following conclusions about the reaction shown below?

A. There is an increase in entropy.
B. Mass is conserved in all chemical reactions.
C. The pressure increases after the reaction goes to completion.
D. The enthalpy value is positive.

[Assistant] B


[User]
<image>
The concentrations of the reactants and products in the reaction represented by the above graph are found to be changing very slowly. Which of the following statements best describes the reaction given that the reaction is exergonic? (ΔG < 0)

A. The reaction is under kinetic control.
B. The reaction has reached a state of equilibrium.
C. The reaction is highly exothermic in nature.
D. The addition of heat will increase the rate of reaction significantly.

[Assistant] A


[User]
<image>
What is the equilibrium expression for the reaction

A. \( K = \frac{[CO_2]^3}{[O_2]^5} \)
B. \( K = \frac{[C_3H_8][O_2]^5}{[CO_2]^3[H_2O]^4} \)
C. \( K = \frac{[C_3H_8]}{[H_2O]^4} \)
D. \( K = \frac{[O_2]^5}{[CO_2]^3} \)

[Assistant] A


[User]
<image>
Given the two standard reduction equations and their potentials below, write the thermodynamically favored chemical reaction and its standard cell potential.

A. $\text{Ag}^+ (\text{aq}) + \text{Mg}^{2+} (\text{aq}) \rightarrow \text{Ag}(\text{s}) + \text{Mg}(\text{s}) & -1.57\ V $
B. $\text{Ag}^+ (\text{aq}) + \text{Mg}(\text{s}) \rightarrow \text{Ag}(\text{s}) + \text{Mg}^{2+} (\text{aq}) & +3.17\ V$
C. $2\text{Ag}^+ (\text{aq}) + \text{Mg}(\text{s}) \rightarrow 2\text{Ag}(\text{s}) + \text{Mg}^{2+} (\text{aq}) & +3.17\ V$
D. $2\text{Ag}^+ (\text{aq}) + \text{Mg}(\text{s}) \rightarrow 2\text{Ag}(\text{s}) + \text{Mg}^{2+} (\text{aq}) & +3.97\ V$

[Assistant] C


[User]
<image>
In the diagram above, which labeled arrow is pointing toward a hydrogen bond?

A. 1
B. 2
C. 3
D. 4

[Assistant] C


[User]
<image>
The graph above shows the distribution of kinetic energies of a large number of Ne atoms at 500 K. Which letter shows the average kinetic energy of this system?
A. A
B. B
C. C
D. D

[Assistant] C


[User]
<image>
Consider the following possible mechanism for the reaction above: \[ \text{2SO}_2(g) + \text{O}_2(g) \rightarrow \text{2SO}_3(g) \] Consider the possible mechanism in the figure for the reaction above. Which of the following statements is true?

A. This mechanism has no free radicals.
B. \(\text{O}_2(g)\) is an intermediate.
C. \(\text{SO}(g)\) is a catalyst for this reaction.
D. The mechanism does not add up to the overall reaction.

[Assistant] A


[User]
<image>
Three 1-liter flasks are connected to a 3-liter flask by valves. The 3-liter flask is evacuated to start and the entire system is at 298K. The first flask contains helium, the second argon, and the third krypton. The pressure of the argon is 633 torr. The amounts of gas are proportional to their representations in the flasks. If all the valves to the center flask are opened, what will the pressure of the system be? Assume the connections have negligible volume.

A. 633 torr
B. 316 torr
C. 1266 torr
D. 211 torr

[Assistant] B


[User]
<image>
A portion of a mass spectrum of neon is presented above. Estimate the average mass of naturally occurring atoms of neon, assuming that the height of each line represents the relative amount of each mass.

A. 20.3
B. 20.0
C. 21.0
D. Not enough information is provided

[Assistant] A


[User]
<image>
The above graph shows a titration curve of a weak base titrated with a strong acid. The pH was measured with a pH meter after small volumes of 0.075 M HCl were added to 25.0 mL of a weak base. Data from that experiment are shown in the graph. Which arrow points to the end point of this titration?

A. A
B. E
C. C
D. F

[Assistant] B


[User]
<image>
The above graph shows a titration curve of a weak base titrated with a strong acid. The pH was measured with a pH meter after small volumes of 0.075 M HCl were added to 25.0 mL of a weak base. Data from that experiment are shown in the graph. Which arrow points to the place on the curve where the pH is equal to 14 - pK$_b$?

A. A
B. E
C. C
D. F

[Assistant] C


[User]
<image>
The above graph shows a titration curve of a weak base titrated with a strong acid. The pH was measured with a pH meter after small volumes of 0.075 M HCl were added to 25.0 mL of a weak base. Data from that experiment are shown in the graph. Find the two points on the curve that indicate the region where the solution can be described as a buffer. What is the change in pH from the first point to the second?

A. 0.5 pH unit
B. 1 pH unit
C. 2 pH units
D. 3 pH units.

[Assistant] C


[User]
<image>
The above graph shows a titration curve of a weak base titrated with a strong acid. The pH was measured with a pH meter after small volumes of 0.075 M HCl were added to 25.0 mL of a weak base. Data from that experiment are shown in the graph. Which of the following describes the base that is being titrated?

A. The base is dibasic since two end points are observed.
B. The concentration of the base is 0.075 $M$.
C. The concentration of the base is slightly more than 0.075 $M$.
D. The concentration of the base is slightly less than 0.075 $M$.

[Assistant] D


[User]
<image>
Refer to the figure.  The Lewis electron-dot structures for sulfur trioxide and for the sulfite ion are given above. Which statement best describes the geometry of these two substances?

A. The sulfite ion has a triangular pyramid shape, and the sulfur trioxide is a planar triangle.
B. Both substances are flat, triangular, planar shapes.
C. Both substances are triangular pyramids.
D. SO$_3$ is a triangular pyramid, and SO$_3^{2-}$ is a planar triangle.

[Assistant] A


[User]
<image>
Refer to the figure. Which statement below describes the charge, polarity, and resonance characteristics of the sulfite ion and of the sulfur trioxide species shown above?

A. The sulfite ion has two negative charges along with a shape that makes it a dipole. Sulfur trioxide is symmetrical and nonpolar. In addition, as written, both have three resonance structures.
B. The sulfite ion and sulfur trioxide are both polar with the only difference being that one is an ion and the other is not.
C. Sulfur trioxide has three resonance structures, and the sulfite ion has no resonance structures.
D. Sulfite ions have a nonbonding electron pair domain, while sulfur trioxide has all electron domains as bonding domains.

[Assistant] B


[User]
<image>
Use the arrangement of atoms suggested in the skeleton structure above to construct the Lewis structure for the SO$_3$ molecule. Which of the following statements about this molecule is incorrect?

A. Sulfur trioxide has three resonance structures.
B. Sulfur trioxide has a planar triangle shape.
C. Sulfur trioxide is nonpolar.
D. The S–O bond order is 5/3.

[Assistant] D


[User]
<image>
Use the arrangement of atoms suggested in the skeleton structure above to construct the Lewis structure for the sulfite ion. Be sure to minimize the formal charges. Which of the following statements is incorrect?

A. The sulfite ion has a double bond.
B. The sulfite ion has a triangular pyramid shape.
C. The sulfite ion is nonpolar.
D. The S–O bond order is 4/3.

[Assistant] C


[User]
<image>
Ethanoic acid (\ce{HC2H3O2} \quad \text{or} \quad \ce{CH3CO2H} \quad \text{or} \quad \ce{CH3COOH}
) has a much lower vapor pressure than ethanol (\ce{CH3CH2OH}). What is the most reasonable explanation?

A. The polarizability of two oxygen atoms increases the London forces of attraction in ethanoic acid compared with ethanol.
B. Hydrogen bonding in ethanoic acid is the strongest attractive force and is mainly responsible for the observed data.
C. Ethanol has an –OH group and can hydrogen bond; therefore, the London forces must cause the effect.
D. Both ethanol and ethanoic acid have an –OH, so the difference is the dipole of the second oxygen that increases the attractive forces.

[Assistant] B


[User]
<image>
Vitamin C is oxidized slowly to dehydroascorbic acid by the oxygen in air. It is catalyzed by ions such as \ce{Cu^2+} and \ce{Fe^3+}
. The reaction can be followed by measuring the ultraviolet absorbance at 243 nm.

Which of the following is the best interpretation of the data given above?

A. The data support a first-order reaction.
B. The data support a second-order reaction.
C. The data support a zero-order reaction.
D. The overall order is 14.

[Assistant] A


[User]
<image>
Choose the description of the point on the distribution curve that is the most plausible.

A. Point A represents absolute zero where all motions stops.
B. Point C is proportional to temperature
C. Point B is where the transition state occurs.
D. At point D, the products of the reaction are found.

[Assistant] B


[User]
<image>
Three 1-liter flasks are connected to a 3-liter flask by valves as shown in the diagram above. The 3-liter flask has the relative number of helium atoms as indicated. At the start, the entire system is at 585K. The first flask contains oxygen; the second contains hydrogen, and the third contains nitrogen. The pressure of hydrogen is 3.00 atm. The number of gas molecules is proportional to their representations in the flasks. If the valves are all opened, what will be the pressure in the system? Assume the connections have negligible volume.

A. 1.0 atm
B. 2.0 atm
C. 3.0 atm
D. 4.0 atm

[Assistant] B


[User]
<image>
A mass spectrum of a naturally occurring sample of an element is shown above. What is the element?

A. Cl
B. S
C. Ar
D. There are two peaks, so there must be two compounds.

[Assistant] A


[User]
<image>
In the diagram above, which labeled arrow is pointing toward a covalent bond and which is pointing toward a hydrogen bond?

A. 1     2
B. 2     1
C. 3     4
D. 4     3

[Assistant] D


[User]
<image>
Space-filling representations of carbon tetrachloride and carbon tetrabromide are shown above. The carbon can be seen in the carbon tetrachloride and is hidden by the bromine in carbon tetrabromide. Which of the following is the most reasonable statement? (Assume that the temperatures of CCl$_4$ and CBr$_4$ are the same in these comparisons.)

A. CCl$_4$ has a higher surface tension compared with CBr$_4$
B. CCl$_4$has a higher vapor pressure compared with CBr$_4$.
C. CCl$_4$ has a higher boiling point compared with CBr$_4$.
D. CCl$_4$ has a higher viscosity compared with CB$_4$.

[Assistant] B


[User]
<image>
Which of the labeled arrows in the diagram above represents the strongest intermolecular force of the four indicated?

A. Arrow A
B. Arrow B
C. Arrow C
D. Arrow D

[Assistant] A


[User]
<image>
According to the data in the table above, which of the compounds has the strongest intermolecular forces?

A. Propylamine
B. Ethyl methyl ether
C. Trimethyl amine
D. Ethyl methyl amine

[Assistant] A


[User]
<image>
Each of the ions in the table form stable oxides (Na$_4$O, CdO, and La$_4$O$_3$). Lanthanum oxide,  La$_4$O$_3$, has a melting point significantly higher than that of the other oxides. Which of the following is the best explanation of why this is true?

A. Lanthanum is a lanthanide element and the melting points of these elements are always high.
B. There is more oxygen in the formula  La$_4$O$_3$ than in the other formulas.
C. Lanthanum had the highest charge; therefore, it has the highest lattice energy.
D. Alkali metals like sodium and transition metals like cadmium tend to have low melting points.

[Assistant] C


[User]
<image>
The diagram above shows the structure of molecules of CS$_2$ and COS. The boiling point of COS is 223 K, and the boiling point of CS2 is 319 K. Which of the following is the best explanation of why the boiling point of CS$_2$ is higher?

A. The molar mass of CS$_2$ is greater.
B. COS has weaker covalent bonds than CS$_2$.
C. Only CS$_2$ can form intermolecular dipole-dipole forces.
D. COS has stronger intermolecular forces because it is polar and CS$_2$ is not.

[Assistant] A


[User]
<image>
Which of the labeled arrows in the diagram above represents the strongest intermolecular force?

A. A
B. B
C. C
D. D

[Assistant] B


[User]
<image>
A dimer consists of two closely associated molecules. In the gas phase, acetic acid tends to form dimers as illustrated on the left in the above diagram. Acetyl chloride, on the right in the above diagram, is not very efficient in forming dimers. Why is acetic acid better able to form dimers than acetyl chloride?

A. The molecular mass of acetyl chloride is higher than that of acetic acid making it harder for the acetyl chloride to form dimers.
B. It is easier to form a covalent bond between acetic acid molecules than between acetyl chloride molecules.
C. Acetic acid can form strong hydrogen bonds but acetyl chloride can only form weaker dipole-dipole attractions.
D. Acetic acid is an acidic compound but acetyl chloride is a neutral compound.

[Assistant] C


[User]
<image>
Which of the compounds in the above diagram is capable of participating in hydrogen bonding?

A. C$_3$H$_9$ N
B. CH$_3$F
C. C$_2$H$_6$O
D. C$_4$H$_11$

[Assistant] D


[User]
<image>
In the diagram above, which labeled arrow is pointing toward a hydrogen bond?

A. 1
B. 2
C. 3
D. 4

[Assistant] C


[User]
<image>
The graph above shows the distribution of kinetic energies of a large number of Ne atoms at 500 K. Which letter shows the average kinetic energy of this system?
A. A
B. B
C. C
D. D

[Assistant] C


[User]
<image>
The above graph shows a titration curve of a weak base titrated with a strong acid. The pH was measured with a pH meter after small volumes of 0.075 M HCl were added to 25.0 mL of a weak base. Data from that experiment are shown in the graph. Which arrow points to the end point of this titration?

A. A
B. E
C. C
D. F

[Assistant] B


[User]
<image>
The above graph shows a titration curve of a weak base titrated with a strong acid. The pH was measured with a pH meter after small volumes of 0.075 M HCl were added to 25.0 mL of a weak base. Data from that experiment are shown in the graph. Which arrow points to the place on the curve where the pH is equal to 14 - pK$_b$?

A. A
B. E
C. C
D. F

[Assistant] C


[User]
<image>
The Lewis diagram for nitric acid, $HNO_3$, is above. Which of the following statements is true regarding nitric acid?
A. $HNO_3$ molecules are planar.
B. The nitrogen atom carries a negative formal charge.
C. All N-O bonds are of identical length.
D. There is a third equivalence resonance structure that is not shown.

[Assistant] A


[User]
<image>
The photoelectron below spectrum is for a neutral fluorine atom. Compared to that spectrum, the spectrum for a fluoride ion would have
A. one more peak
B. one less peak
C. the same number of peaks, but the rightmost peak would be taller
D. the same number of peaks, but the leftmost peak would be taller

[Assistant] C


[User]
<image>
A student is attempting to use a distillation apparatus, shown below, to separate a mixture of propanol (boiling point: 97°C) and propionic acid (boiling point: 141°C). Which temperature should the apparatus be set at to obtain as pure a distillate of propanol as possible?
A. 85°C
B. 105°C
C. 125°C
D. 145°C

[Assistant] B


[User]
<image>
Given the half-reactions below, what would the coefficient on the $NO(g)$ be when the full reaction below is balanced?
A. 1
B. 2
C. 3
D. 4

[Assistant] B


[User]
<image>
A Lewis diagram of the hydrogen phosphate ion is shown below. Based on this diagram, which of the atoms would have a negative formal charge?
A. P
B. Ox
C. Oy
D. Oz

[Assistant] D


[User]
<image>
The $K_a$ values for three different weak acids are given below. If the acid is polyprotic, all of the $K_a$ values for that acid are given. If each acid were to be titrated with 0.10 M NaOH, which solution would have the highest pH at the endpoint of the titration when each acid has fully reacted?
A. Formic
B. Sulfurous
C. Citric
D. All titrations would have identical pHs at the endpoint.

[Assistant] B


[User]
<image>
A piece of potassium metal is added to a solution of hydrochloric acid, and the metal starts to react. Which of the following is the correct net ionic equation for the reaction that is occurring?
A. $2H^+(aq) + K^+(aq) + 3e^- \rightarrow H_2(g) + K(s)$
B. $2H^+(aq) + 2K^+(aq) + 4e^- \rightarrow 2K(s) + H_2(g)$
C. $2H^+(aq) + K(s) \rightarrow K^+(aq) + H_2(g)$
D. $2H^+(aq) + 2K(s) \rightarrow 2K^+(aq) + H_2(g)$

[Assistant] D


[User]
<image>
The Lewis diagram of the bisulfite ion, $HSO^{3-}$, is drawn below. Which of the following descriptions correctly compares the bond lengths of the three sulfur-oxygen bonds found in bisulfite?
A. All bonds are the same length.
B. Of the three bonds, there is one longer one and two shorter ones of identical length.
C. Of the three bonds, there are two longer ones of identical length and one shorter one.
D. All three bonds are different lengths.

[Assistant] B


[User]
<image>
A sample of hydrogen peroxide, $H_2O_2$, will decompose over time. The graph below charts the concentration of an $H_2O_2$ sample over time. What is the rate law for the overall reaction?
A. Rate = k
B. Rate = k[$H_2O_2$]
C. Rate = k[$H_2O_2$]2
D. Rate = k[$H_2O$][$O_2$]

[Assistant] B


[User]
<image>
A semiconductor with a silicon lattice is doped by the addition of another element, symbolized by the letter X in the diagram below. Which of the following statements best describes the possible identity of the element as well as the type of doping that is occurring?
A. Boron, which has less valence electrons than silicon and creates positive "holes" in the lattice
B. Phosphorus, which has extra valence electrons and creates a mobile negative charge in the lattice
C. Aluminum, which has metalloid properties that lend to increased conductivity when added to a semiconductor
D. Carbon, which has an equal number of valence electrons as silicon and strengthens the conducting lattice

[Assistant] A


[User]
<image>
Given the bond enthalpy values in the data table below, determine the enthalpy change for the reaction above it.
A. -1220 kJ/mol
B. -400 kJ/mol
C. 400 kJ/mol
D. 1220 kJ/mol

[Assistant] A


[User]
<image>
$[NO]$ (M)       $[O_2]$ (M)
The reaction below is run with the concentration of both reactants at 0.10 M. Which of the following values for the initial concentration of both reactants would lead to an initial reaction rate which is double that of the first trial?
A.      0.15       0.15
B.      0.20       0.20
C.      0.20       0.050
D.      0.050       0.20

[Assistant] C


[User]
<image>
Two batteries are constructed via the diagram below. The concentration of the solutions and the mass of the electrodes are identified in the data below the diagram. How would the voltage and the battery life for the two batteries compare?Voltage       Battery Life
A. X <Y       X <Y
B. X <Y       X =Y
C. X =Y       X = Y
D. X =Y       X < Y

[Assistant] D


[User]
<image>
$Cu^{2+}$ ions appear blue in solution, and the $NO_3^-$ ion is colorless. The absorbance of a $Cu(NO_3)_2$ solution is measured at various wavelengths using a spectrophotometer. To determine the concentration of a $Cu(NO_3)_2$ solution of unknown concentration, what wavelength of light would produce the best results?
A. 350 nm
B. 500 nm
C. 640 nm
D. 800 nm

[Assistant] C


[User]
<image>
The diagram below supports which of the following conclusions about the reaction shown below?
A. There is an increase in entropy.
B. Mass is conserved in all chemical reactions.
C. The pressure increases after the reaction goes to completion.
D. The enthalpy value is positive.

[Assistant] B


[User]
<image>
Ox       N       Oy
One of the resonance structures for the nitrite ion is shown below. What is the formal charge on each atom?
A.      -1       +1       -1
B.      +1       -1       0
C.      0       0       -1
D.      -1       0       0

[Assistant] D


[User]
<image>
Identify the three gases represented on the Maxwell-Boltzmann diagram below. Assume all gases are at the same temperature.I       II       III
A.      $H_2$       $N_2$       $F_2$
B.      $H_2$       $F_2$       $N_2$
C.      $F_2$       $N_2$       $H_2$
D.      $N_2$       $F_2$       $H_2$

[Assistant] C


[User]
<image>
If the $H_2C_2O_4$ were to be replaced with an identical volume of $H_2SO_4$, what volume of $NaOH$ would be required to fully neutralize the acid?
A 0.10 M solution of $NaOH$ is titrated into 20 mL of $H_2C_2O_4$, a diprotic acid, of an unknown concentration. The pH of the $H_2C_2O_4$ solution is monitored as the $NaOH$ is added to it, resulting in the below graph.
A. 10 mL
B. 20 mL
C. 40 mL
D. 60 mL

[Assistant] B


[User]
<image>
5mL      15mL      25mL

Phenolphthalein is an acid-base indicator with a pKa of 9.1. Its protonated form is often abbreviated as $HIn$, while its conjugate base is abbreviated as $In^-$. At the following volumes of NaOH added, select the option that accurately describes which form of the indicator will be present in a greater concentration.
A 0.10 M solution of NaOH is titrated into 20 mL of $H_2C_2O_4$, a diprotic acid, of an unknown concentration. The pH of the $H_2C_2O_4$ solution is monitored as the NaOH is added to it, resulting in the below graph.
A. $HIn$      $HIn$      $In^-$
B. $HIn$      $In^-$      $In^-$
C. $In^--$     $In^-$      $HIn$
D. $In^-$      $HIn$      $HIn$

[Assistant] A


[User]
<image>
At the point at which 20 mL of NaOH has been added, which of the following species is present in the greatest concentration in solution?

A 0.10 M solution of NaOH is titrated into 20 mL of $H_2C_2O_4$, a diprotic acid, of an unknown concentration. The pH of the $H_2C_2O_4$ solution is monitored as the NaOH is added to it, resulting in the below graph.
A. $H^+$
B. $OH^-$
C. $HC_2O_4^-$
D. $C_2O_4^{2-}$

[Assistant] D


[User]
<image>
What is the concentration of the $H_2C_2O_4$ solution?

A 0.10 M solution of NaOH is titrated into 20 mL of $H_2C_2O_4$, a diprotic acid, of an unknown concentration. The pH of the $H_2C_2O_4$ solution is monitored as the NaOH is added to it, resulting in the below graph.
A. 0.025 M
B. 0.050 M
C. 0.10 M
D. 0.20 M

[Assistant] B


[User]
<image>
Data considering the conductivity of four different substances in their various phases is given in the table below. Of the four options, which substance is most likely to be $NaCl$?
A. Substance A
B. Substance B
C. Substance C
D. Substance D

[Assistant] B


[User]
<image>
As shown below, four identical containers hold the same number of moles of four different gases at 298 K. If ideal behavior is NOT assumed, in which container would the pressure be the lowest?
A. $H_2O$
B. $CH_4$
C. $Ne$
D. $He$

[Assistant] A


[User]
<image>
Based on the mass spectrum shown below, which of the following can be concluded about zirconium?
A. The most common charge on a zirconium ion is +2.
B. Zirconium nuclei can have different number of protons.
C. The average atomic mass of a zirconium atom is 90 amu.
D. The most common isotope of zirconium has 50 neutrons.

[Assistant] D


[User]
<image>
The system below is at equilibrium. If it were to be diluted, what would happen to the moles of reactants and the moles product after equilibrium is reestablished?Mole Reactants      Moles Product
A. Increase      Increase
B. Increase      Decrease
C. Decrease      Decrease
D. No Change      No Change

[Assistant] B


[User]
<image>
A sample of some $N_2O_5$ gas is placed in a sealed container and allowed to decompose. The concentration of the $N_2O_5$ is tracked over time, and the results are plotted on the above graph. Which of the following represents the possible units on the rate constant for this reaction?
A. $s^{-1}$
B. $sM^{-1}$
C. $Ms^{-1}$
D. $Ms^{-2}$

[Assistant] A


[User]
<image>
Vapor Pressure @ 25°C (torr)

Substance
Three different liquids are mixed together in a flask, and that flask is then hooked up to a distillation apparatus, as shown below. The liquids are initially at 25°C, and the heat is turned up until the mixture starts to boil. Which liquid would be the first to separate out of the mixture?
A. $H_2O$
B. $CH_3OH$
C. $C_6H_{12}$
D. Distillation would be an ineffective method of separating the mixture.

[Assistant] B


[User]
<image>
1.0 mole of $NO_2(g)$ is bubbled through excess water, causing the above reaction to take place. Which of the following statements correctly describes the energy change that will occur during the reaction?
A. 135 kJ of energy will be emitted.
B. 45 kJ of energy will be emitted.
C. 135 kJ of energy will be absorbed.
D. 405 kJ of energy will be absorbed.

[Assistant] B


[User]
<image>
A beaker is filled with some 1.0 M $CuSO_4$, and two carbon electrodes are placed in the beaker with a battery wired between them, as shown below. As current is run through the system, solid copper plates out onto the carbon cathode. Which of the following changes would increase the amount of solid copper that is plated out of solution?
A. Replacing the 1.0 M $CuSO_4$ solution with 1.0 M $CuCl_2$
B. Using a 9.0 V battery instead of a 1.5 V battery
C. Decreasing the pH of the solution
D. Changing out the carbon electrodes with platinum electrodes

[Assistant] B


[User]
<image>
The photoelectron spectrum of an element is below. Based on the spectrum, what is the charge on the most common ion of the element?
A. -2
B. -1
C. +1
D. +2

[Assistant] D


[User]
<image>
A beaker of saturated zinc iodate is left out overnight. The following morning, some water is found to have evaporated. Assuming the temperature remained constant at 25°C, which of the following options correctly identifies the changes in the $[Zn^{2+}]$ and the mass of the zinc iodate present in the beaker compared to the previous night?
Zinc iodate dissociates in water via the following equilibrium process $[Zn^{2+}]$       Mass Zn(IO3)2
A.      Increase       Decrease
B.      Increase       No Change
C.      No Change       Increase
D.      No Change       Decrease

[Assistant] C


[User]
<image>
Zinc iodate dissociates in water via the following equilibrium process. Which of the following solutions would zinc iodate be the LEAST soluble in?
A. 1.0 M BaCl2
B. 1.0 M NaIO3
C. 1.0 M K2CO3
D. Pure water

[Assistant] B


[User]
<image>
What is the approximate molar solubility of zinc iodate at 25°C?
Zinc iodate dissociates in water via the following equilibrium process
A. $1.0 \times 10^{-2}$ M
B. $2.0 \times 10^{-3}$ M
C. $4.0 \times 10^{-6}$ M
D. $1.0 \times 10^{-6}$ M

[Assistant] A


[User]
<image>
When the oxidation-reduction reaction below is completely balanced, what is the coefficient on the $MnO_4^-$ ion?
A. 1
B. 2
C. 3
D. 4

[Assistant] B


[User]
<image>
The mass spectrum below shows the distribution of various isotopes of strontium. Based on the data, which of the following conclusions can be drawn?
A. Strontium most commonly forms ions with a charge of +2.
B. Strontium isotopes with a mass of 86 or 87 are very unstable.
C. The number of protons in a strontium atom nucleus can vary.
D. The most common isotope of strontium has 50 neutrons.

[Assistant] D


[User]
<image>
The Lewis diagrams for both ethanol and octane are drawn below. Ethanol's boiling point is 78°C, while octane's is 125°C. This is best explained by the fact that
A. octane has hydrogen bonding, while ethanol does not
B. octane has a significantly higher molar mass than ethanol
C. octane's temporary dipoles are stronger than those in ethanol
D. octane is more symmetrical than ethanol

[Assistant] C


[User]
<image>
If a small, pinhole-size leak were to be drilled into each container, the container with which gas would experience the fastest pressure decrease?
10.0 g each of three different gases are present in three glass containers of identical volume, as shown below. The temperature of all three flasks is held constant at 298 K.
A. $SO_2$
B. $CH_4$
C. $NCl_3$
D. All three containers would decrease pressure at the same rate.

[Assistant] B


[User]
<image>
10.0 g each of three different gases are present in three glass containers of identical volume, as shown below. The temperature of all three flasks is held constant at 298 K.Which of the gases would have the greatest density?
A. $SO_2$
B. $CH_4$
C. $NCl_3$
D. All three gases would have the same density.

[Assistant] D


[User]
<image>
The container with which gas would have the greatest pressure?
10.0 g each of three different gases are present in three glass containers of identical volume, as shown below. The temperature of all three flasks is held constant at 298 K.
A. $SO_2$
B. $CH_4$
C. $NCl_3$
D. All four containers would have the same pressure.

[Assistant] B


[User]
<image>
$SiCl_4$      $PCl_3$
The Lewis diagrams for $SiCl_4$ and $PCl_3$ are drawn below. What are the approximate bond angles between the terminal chlorine atoms in each structure?
A. 90      90
B. 109.5°     < 109.5°
C. 90°     109.5°
D. < 109.5°     > 90°

[Assistant] B


[User]
<image>
X     Y     Z
The formate ion, $HCO_2^-$, is best represented by the Lewis diagram below. Each bond is labeled with a different letter.What is the bond order for each bond?
A. 1     1     2
B. 2     2     1
C. 1     1.5     1.5
D. 1.33     1.33     1.33

[Assistant] C


[User]
<image>
Initial pH      Equivalence pH      Ending pH
A student titrates some 1.0 M $HCl$ into 20.0 mL of methylamine ($CH_3NH_2$), a weak base which only accepts a single proton. The following titration curve results:The methylamine is replaced by 20.0 mL of sodium hydroxide of an identical concentration. If the sodium hydroxide is titrated with the 1.0 M $HCl$, which of the following options accurately describes the pH levels at various points during the titration when compared to the pH levels at the same point in the $HCl$/methylamine titration?
A. lower     same     higher
B. higher     higher     same
C. same     higher     same
D. higher     lower     lower

[Assistant] B


[User]
<image>
The buffer region of this titration is located
A student titrates some 1.0 M $HCl$ into 20.0 mL of methylamine ($CH_3NH_2$), a weak base which only accepts a single proton. The following titration curve results:
A. below 3.0 mL
B. between 3.0 mL and 14.0 mL
C. between 14.0 mL and 16.0 mL
D. above 16.0 mL

[Assistant] B


[User]
<image>
What is the approximate $pK_b$ for methylamine?
A student titrates some 1.0 M HCl into 20.0 mL of methylamine ($CH_3NH_2$), a weak base which only accepts a single proton. The following titration curve results:
A. 3.5
B. 5.5
C. 10.5
D. 12.5

[Assistant] A


[User]
<image>
What is the concentration of the methylamine?
A student titrates some 1.0 M HCl into 20.0 mL of methylamine ($CH_3NH_2$), a weak base which only accepts a single proton. The following titration curve results:
A. 0.50 M
B. 0.75 M
C. 1.0 M
D. 1.25 M

[Assistant] B


[User]
<image>
Silver sulfate, $Ag_2SO_4$, has a solubility product constant of $1.0 \times 10^{-5}$. The below diagram shows the products of a precipitation reaction in which some silver sulfate was formed.Which ion concentrations below would have led the precipitate to form?
A. $[Ag^+] = 0.01 M$ $[SO_4^{2-}] = 0.01 M$
B. $[Ag^+] = 0.10 M$ $[SO_4^{2-}] = 0.01 M$
C. $[Ag^+] = 0.01 M$ $[SO_4^{2-}] = 0.10 M$
D. This is impossible to determine without knowing the total volume of the solution.

[Assistant] B


[User]
<image>
Silver sulfate, $Ag_2SO_4$, has a solubility product constant of $1.0 \times 10^{-5}$. The below diagram shows the products of a precipitation reaction in which some silver sulfate was formed.If the beaker above were left uncovered for several hours
A. some of the $Ag_2SO_4$ would dissolve
B. some of the spectator ions would evaporate into the atmosphere
C. the solution would become electrically imbalanced
D. additional $Ag_2SO_4$ would precipitate

[Assistant] D


[User]
<image>
Silver sulfate, $Ag_2SO_4$, has a solubility product constant of $1.0 \times 10^{-5}$. The below diagram shows the products of a precipitation reaction in which some silver sulfate was formed.What is the identity of the excess reactant?
A. $AgNO_3$
B. $Ag_2SO_4$
C. $NaNO_3$
D. $Na_2SO_4$

[Assistant] A


[User]
<image>
The following curve is obtained during the titration of 30.0 mL of 1.0 M $NH_3$, a weak base, with a strong acid:What ions are present in significant amounts during the first buffer region?
A. $NH_3$ and $NH_4^+$
B. $NH_3$ and $H^+$
C. $NH_4^+$ and $OH^-$
D. $H_3O^+$ and $NH_3$

[Assistant] A


[User]
<image>
The following curve is obtained during the titration of 30.0 mL of 1.0 M NH3, a weak base, with a strong acid:What is the concentration of the acid?
A. 0.5 M
B. 1.0 M
C. 1.5 M
D. 2.0 M

[Assistant] D


[User]
<image>
Why is the solution acidic at equilibrium?
The following curve is obtained during the titration of 30.0 mL of 1.0 M NH3, a weak base, with a strong acid:
A. The strong acid dissociates fully, leaving excess $[H^+]$ in solution.
B. The conjugate acid of NH3 is the only ion present at equilibrium.
C. The water which is being created during the titration acts as an acid.
D. The acid is diprotic, donating two protons for every unit dissociated.

[Assistant] B


[User]
<image>
The diagram below shows three identical 1.0 L containers filled with the indicated amounts of gas. The stopcocks connecting the containers are originally closed and the gases are all at 25°C. Assume ideal behavior.The stopcocks are opened. If the tubing connecting the containers has negligible volume, by what percentage will the pressure exerted by the neon gas decrease?
A. 25%
B. 33%
C. 50%
D. 67%

[Assistant] D


[User]
<image>
The diagram below shows three identical 1.0 L containers filled with the indicated amounts of gas. The stopcocks connecting the containers are originally closed and the gases are all at 25°C. Assume ideal behavior.Which gas has the strongest IMFs?
A. He
B. Ne
C. NO
D. All gases have identical IMFs.

[Assistant] D


[User]
<image>
The diagram below shows three identical 1.0 L containers filled with the indicated amounts of gas. The stopcocks connecting the containers are originally closed and the gases are all at 25°C. Assume ideal behavior. Which gas exerts the greatest pressure?
A. He
B. Ne
C. NO
D. All gases exert the same amount of pressure.

[Assistant] A


[User]
<image>
Which structure is more likely to correspond with the actual Lewis diagram for the sulfate ion?
There are several different potential Lewis diagrams for the sulfate ion, two of which are below.
A. Structure A; single bonds are more stable than double bonds
B. Structure A; it has the most unshared pairs of electrons
C. Structure B; there are more possible resonance structures
D. Structure B; fewer atoms have formal charges

[Assistant] D


[User]
<image>
Which of the following statements regarding the structure B is true?
There are several different potential Lewis diagrams for the sulfate ion, two of which are below.
A. The double bonds must be located opposite of each other due to additional electron repulsion.
B. It is a more polar molecule than the molecule represented by structure A.
C. The bonds in the molecule are weaker than those in structure A.
D. All bonds in the molecule are identical to each other.

[Assistant] D


[User]
<image>
What is the S-O bond order in the structure B?
There are several different potential Lewis diagrams for the sulfate ion, two of which are below.
A. 1.0
B. 1.33
C. 1.5
D. 1.67

[Assistant] C


[User]
<image>
What is the molecular geometry in the structure A?
There are several different potential Lewis diagrams for the sulfate ion, two of which are below.
A. Tetrahedral
B. Trigonal Planar
C. Trigonal Pyramidal
D. Octahedral

[Assistant] A


[User]
<image>
Use the PES spectra below to answer questions.How many valence electrons does this atom have?
A. 2
B. 3
C. 4
D. 5

[Assistant] D


[User]
<image>
An electron from which peak would have the greatest velocity after ejection?
Use the PES spectra below to answer questions.
A. The peak at 104 MJ/mol
B. The peak at 6.84 MJ/mol
C. The peak at 4.98 MJ/mol
D. The peak at 1.76 MJ/mol

[Assistant] D


[User]
<image>
How many significant digits are present in the temperature read from the thermometer illustrated to the right?

A.1
B.2
C.3
D.4

[Assistant] C


[User]
<image>
The marks on the following target represent someone who is:

A.accurate, but not precise.
B.precise, but not accurate.
C.both accurate and precise.
D.neither accurate nor precise.

[Assistant] D


[User]
<image>
Pictured below is a schematic of the Rutherford experiment.  Which scattered -particle gives the best evidence for the nuclear atom?

A. a
B. b
C. c
D. d

[Assistant] A


[User]
<image>
What position on the standing wave shown below corresponds to a crest?

A. a
B. b
C. c
D. d
E. e

[Assistant] B


[User]
<image>
The value of l that is related to the following orbital is:

A. 0
B. 1
C. 2
D. 3
E. 4

[Assistant] B


[User]
<image>
The titration curves labeled 1 and 2 were obtained by titrating equal volumes of two different acid samples with portions of the same sodium hydroxide solution. What conclusions can be drawn about the relative concentrations and strengths of acids 1 and 2 from these curves?

(A)	The concentrations are the same but acid 1 is weaker than acid 2.
(B)	The concentrations are the same but acid 1 is stronger than acid 2.
(C)	Acid 1 is the same strength as acid 2, but it is less concentrated.
(D)	Acid 1 is the same strength as acid 2, but it is more concentrated.

[Assistant] A


[User]
<image>
According to the above data, what is the half-life of the substance?

A. 1.0 hrs
B. 2.3 hrs
C. 3.0 hrs
D. 8.0 hrs

[Assistant] C


[User]
<image>
What percent of the original sample remains after 4 hours?

A. 80%
B. 75%
C. 60%
D. 40%

[Assistant] D


[User]
<image>
The elements I and Te have similar average atomic masses. A sample that was believed to be a mixture of I and Te was run through a mass spectrometer which separates a sample by mass into isotopes, resulting in the data below. All of the following statements are true. Which one would be the best basis for concluding that the sample was pure Te?

A. Te forms ions with a -2 charge, whereas I forms ions with a -1 charge.
B. Te is more abundant than I in the universe.
C. I consists of only one naturally occurring isotope with 74 neutrons, whereas Te has more than one isotope
D. I has a higher first ionization energy than Te does.

[Assistant] C


[User]
<image>
The diagram below models a change that occurs in matter. Based on what you know about changes in matter, explain why the diagram shows a physical change rather than a chemical change.

A. The particles get smaller.
B. The volume of the matter decreases.
C. The composition of the matter stays the same.
D. The particles change into particles of different substances

[Assistant] C


[User]
<image>
In an experiment, a solid 1 molar sample of Substance A was gradually heated by a source of constant energy for several hours and the temperature was measured periodically. At the end of the heating period, Substance A had been converted to the gas phase. The heating curve produced by this experiment is shown below. During the course of the experiment, there was a period of time when the phase of Substance A was in equilibrium with the liquid phase. At what temperature did this occur?

(A) Between 100 K and 150 K
(B) At 150 K
(C) Between 150 K and 250 K
(D) At 250 K
(E) Between 250 K and 350 K

[Assistant] B


[User]
<image>
In an experiment, a solid 1 molar sample of Substance A was gradually heated by a source of constant energy for several hours and the temperature was measured periodically. At the end of the heating period, Substance A had been converted to the gas phase. The heating curve produced by this experiment is shown below. Based on the data given in the heating curve,which of the following statements is NOTtrue regarding Substance A?

(A) The boiling point of Substance A is 250 K.
(B) The freezing point of Substance A is150 K.
(C) The heat of vaporization of Substance A is greater than the heat of fusion.
(D) Substance A is a liquid at room temperature.
(E) The intermolecular forces exhibited by Substan

[Assistant] D


[User]
<image>
In an experiment, a solid 1 molar sample of Substance A was gradually heated by a source of constant energy for several hours and the temperature was measured periodically. At the end of the heating period, Substance A had been converted to the gas phase. The heating curve produced by this experiment is shown below. During the course of the experiment,Substance A was gradually heated from 100K to 350 K. When the temperature reached 250 K, the energy absorbed by Substance A?

(A} was used to change from liquid to gas phase.
(B) was used to change from gas to liquid phase.
(C) was used to change from solid to liquid phase.
(D) was used to change from liquid to solid phase.
(E) was reduced to zero.

[Assistant] A


[User]
<image>
Which of the following is true of the reactions shown in the diagram above?

(A) The reaction is endothermic because the reactants are at a higher energy level than the products.
(B) The reaction is endothermic because the reactants are at a lower energy level than the products.
(C) The reaction is exothermic because the reactants are at a higher energy level than the products.
(D) The reaction is exothermic because the reactants are at a lower energy level than the products.
(E) The reaction is endothermic because the reactants are at the same energy level as the products.

[Assistant] C


[User]
<image>
Which point on the graph shown above corresponds to an activated complex or transition state?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

[Assistant] C


[User]
<image>
The following titration curve shows the titration of a weak base with a strong acid. Which of the following values most accurately approximates the p$K_b$ of the weak base?

(A) 9.8
(B) 8.4
(C) 7
(D) 3.3
(E) 4.2

[Assistant] E


[User]
<image>
Given a reaction A+B →C. Based on the following experimental data, what is the rate law for the hypothetical reaction given above?

(A) Rate= $k[A]$
(B) Rate= $k[A]^2$
(C) Rate = $k[B]$
(D) Rate = $k[B]^2$
(E) Rate = $k[A][B]$

[Assistant] C


[User]
<image>
Given a reaction A+B →C. Based on the following experimental data, what is the rate law for the hypothetical reaction given above?

(A) Rate= $k[A]$
(B) Rate= $k[A]^2$
(C) Rate = $k[B]$
(D) Rate = $k[B]^2$
(E) Rate = $k[A][B]$

[Assistant] E


[User]
<image>
Given a reaction A+B →C. Based on the following experimental data, what is the rate law for the hypothetical reaction given above?

(A) Rate= $k[A][B]$
(B) Rate= $k[A]^2$
(C) Rate = $k[A][B]^2$
(D) Rate = $k[B]^2$
(E) Rate = $k[A]^2[B]^2$

[Assistant] C


[User]
<image>
 The formal charge on carbon in the molecule below is.

A) 0
B) +1
C) -1
D) +3
E) +2

[Assistant] A


[User]
<image>
The molecular geometry of the left-most carbon atom in the molecule below is:

A) octahedral
B) tetrahedral
C) trigonal planar
D) T-shaped
E) trigonal bipyramidal

[Assistant] B


[User]
<image>
The bond angles marked a, b, and c in the molecule below are about __________, __________, and __________,
respectively.

A) 120, 120, 90
B) 90, 90, 90
C) 120, 120, 109.5
D) 109.5, 90, 120
E) 109.5, 120, 109.5

[Assistant] E


[User]
<image>
Based on molecular mass and dipole moment of the five compounds in the table below, which should have the
highest boiling point?

A) $CH_3OCH_3$
B) $CH_3CN$
C) $CH_3CHO$
D) $CH_3Cl$
E) $CH_3CH_2CH_3$

[Assistant] B


[User]
<image>
On the phase diagram above, segment __________ corresponds to the conditions of temperature and pressure under which the solid and the gas of the substance are in equilibrium.

A) CD
B) AB
C) AD
D) BC
E) AC

[Assistant] E


[User]
<image>
The phase diagram of a substance is given above. The region that corresponds to the solid phase is __________.
A) w
B) x
C) y
D) z
E) x and y

[Assistant] A


[User]
<image>
Based on the figure above, the boiling point of ethyl alcohol under an external pressure of 0.0724 atm is
________eC.

A) 60
B) 20
C) 70
D) 80
E) 40

[Assistant] B


[User]
<image>
The graph shown below depicts the relationship between concentration and time for the following chemical
reaction. The slope of this line is equal to __________.
A) -k
B) -1/k
C) k
D) ln[A]o
E) 1/k

[Assistant] A


[User]
<image>
Which energy difference in the energy profile below corresponds to the activation energy for the forward
reaction?

A) x
B) y
C) x + y
D) y - x
E) x - y

[Assistant] A


[User]
<image>
A 25.0-mL sample of a solution of a monoprotic acid is titrated with a 0.115 M NaOH solution. The titration
curve above was obtained. Which of the indicators in the table would be best for this titration?

A) bromocresol purple
B) bromthymol blue
C) thymol blue
D) phenolpthalein
E) methyl red

[Assistant] B


[User]
<image>
Consider the following table of $K_{sp}$ values. Which compound listed below has the greatest molar solubility in water?

A) $ZnCO_3$
B) $CdCO_3$
C) $CaF_2$
D) $AgI$
E) $Cd(OH)_2$

[Assistant] C


[User]
<image>
Consider the following table of $K_{sp}$ values. The solubility of manganese hydroxide ($Mn(OH)_2$) is 2.2e-5 M. What is the Ksp of $Mn(OH)_2$?

A) 2.1e-14
B) 4.3e-14
C) 1.1e-14
D) 2.2e-5
E) 4.8e-10

[Assistant] B


[User]
<image>
Consider the following table of $K_{sp}$ values. The molar solubility of __________ is not affected by the pH of the solution.

A) $AlCl_3 $
B) $Na_3PO_4$
C) $NaF$
D) $KNO_3$
E) $MnS$

[Assistant] D


[User]
<image>
Consider the following table of $K_{sp}$ values. In which of the following aqueous solutions would you expect AgCl to have the lowest solubility?

A) 0.020 $AgNO_3$
B) 0.020 M $BaCl_2$
C) pure water
D) 0.015 $NaCl$
E) 0.020 $KCl$

[Assistant] B


[User]
<image>
The equilibrium position corresponds to which letter on the graph of G vs f (course of reaction) below?

A) A
B) B
C) C
D) D
E) E

[Assistant] C