AP Chem Quiz
Questions: 16 · 10 minutes
1. What is the ground-state electron configuration of a sodium ion, Na+?
1s^2 2s^2 2p^6 3s^1, totaling eleven electrons
1s^2 2s^2 2p^5, totaling nine electrons
1s^2 2s^2 2p^6, totaling ten electrons
1s^2 2s^2 2p^6 3s^2, totaling twelve electrons
2. An ideal gas is sealed in a rigid container. Its temperature increases from 300 K to 600 K. What happens to its pressure?
It decreases to one-half its original value.
It increases to twice its original value.
It increases to four times its original value.
It remains unchanged because the volume is fixed.
3. During a reaction in a coffee-cup calorimeter, the surrounding solution becomes warmer. Which conclusion is most consistent with this observation?
The reaction is endothermic, and ΔH for the system is positive.
The reaction is at equilibrium, so ΔH equals zero.
The reaction is exothermic, and ΔH for the system is negative.
The reaction absorbs heat while the surroundings also absorb heat.
4. Methane burns according to CH4 + 2 O2 → CO2 + 2 H2O. If methane is in excess, how many moles of CO2 can form from 3.2 mol of O2?
3.2 mol
1.6 mol
6.4 mol
0.80 mol
5. For a reaction at a fixed temperature, the reaction quotient Q is smaller than the equilibrium constant K. What will occur as the system moves toward equilibrium?
The equilibrium constant decreases until it equals Q.
The net reaction proceeds toward reactants until Q becomes zero.
No net change occurs because Q and K need not be equal.
The net reaction proceeds toward products until Q equals K.
6. Ethanol and dimethyl ether have the same molecular formula, C2H6O, but ethanol has the higher boiling point. What best explains the difference?
Ethanol molecules can form hydrogen bonds with one another.
Dimethyl ether is ionic, whereas ethanol is molecular.
Ethanol has a much greater molar mass than dimethyl ether.
Dimethyl ether has no intermolecular attractions.
7. According to VSEPR theory, what is the molecular geometry of SF4?
Seesaw
Square planar
Trigonal planar
Tetrahedral
8. A reaction follows the rate law rate = k[A]^2[B]. If [A] is doubled while [B] remains constant, how does the reaction rate change?
It doubles.
It remains unchanged.
It increases by a factor of eight.
It increases by a factor of four.
9. In a functioning galvanic cell, where does oxidation occur, and in which direction do electrons travel through the external circuit?
Oxidation occurs at the cathode, and electrons travel from cathode to anode.
Oxidation occurs at the cathode, and electrons travel from anode to cathode.
Oxidation occurs at the anode, and electrons travel from cathode to anode.
Oxidation occurs at the anode, and electrons travel from anode to cathode.
10. Aqueous AgNO3 and NaCl are mixed, producing a precipitate. What is the net ionic equation?
Na+(aq) + NO3−(aq) → NaNO3(s)
Ag+(aq) + Cl−(aq) → AgCl(s)
AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)
Ag+(aq) + NO3−(aq) → AgNO3(s)
11. At the equivalence point in the titration of a weak monoprotic acid with a strong base, which description is generally correct?
The pH is below 7 because excess weak acid remains.
The pH is exactly 7 because equal moles have reacted.
The pH is above 7 because the conjugate base reacts with water to form OH−.
The pH is determined only by the concentration of strong base added after equivalence.
12. A student dilutes 25.0 mL of 2.00 M NaCl solution to a total volume of 100.0 mL. What is the final NaCl concentration?
0.125 M
2.00 M
0.500 M
8.00 M
13. A buffer contains equal concentrations of a weak acid, HA, and its conjugate base, A−. What relationship applies?
The pH equals the pKa of HA.
The pH equals 7 at every temperature.
The pOH equals the pKa of HA.
The pH equals the Ka of HA.
14. Why is the atomic radius of magnesium larger than that of sulfur?
Magnesium has more occupied principal energy levels than sulfur.
Sulfur has a greater effective nuclear charge that pulls electrons in the same principal level closer.
Sulfur has fewer protons, so its electrons experience less attraction.
Magnesium has a completely filled valence shell that repels its core electrons.
15. What effect does a catalyst have on a reversible reaction at constant temperature?
It increases the equilibrium constant by favoring products.
It shifts equilibrium toward the side with lower enthalpy.
It lowers the activation energy only for the forward reaction.
It lowers activation energies for both directions without changing the equilibrium position.
16. Two atoms are isotopes of the same element. Which statement must be true?
They have the same number of protons but different numbers of neutrons.
They have the same number of neutrons but different numbers of protons.
They have identical mass numbers but different charges.
They have different atomic numbers but identical electron configurations.