Master AP Chemistry Practice Test: 20 Medium Questions

Question 1

A sample of gas occupies 2.50 L at 25°C and 1.00 atm. What volume will it occupy at 50°C and 0.500 atm, assuming ideal behavior?

Accepted Answer

5.43 L

Question 2

Which of the following molecules has a trigonal pyramidal molecular geometry?

Accepted Answer

NH₃

Question 3

The rate law for a reaction is found to be rate = k[A]²[B]. If the concentration of A is doubled while B remains constant, by what factor does the rate increase?

Accepted Answer

4

Question 4

What is the pH of a 0.020 M solution of HNO₃?

Accepted Answer

1.70

Question 5

Which of the following represents the electron configuration of a ground-state Fe²⁺ ion?

Accepted Answer

[Ar]3d⁶

Question 6

A voltaic cell is constructed using Zn/Zn²⁺ and Cu/Cu²⁺ half-cells. Given E°(Zn²⁺/Zn) = -0.76 V and E°(Cu²⁺/Cu) = +0.34 V, what is the standard cell potential?

Accepted Answer

+1.10 V

Question 7

Which of the following aqueous solutions has the highest boiling point?

Accepted Answer

0.10 m K₃PO₄

Question 8

For the equilibrium reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g), ΔH° = -92 kJ/mol. Which change will shift the equilibrium to produce more NH₃?

Accepted Answer

Removing NH₃ as it forms

Question 9

What is the hybridization of the central carbon atom in formaldehyde (H₂CO)?

Accepted Answer

sp²

Question 10

A first-order reaction has a half-life of 20 minutes. How long will it take for the concentration to decrease to 12.5% of its initial value?

Accepted Answer

60 minutes

Question 11

Which of the following compounds would be expected to have the highest lattice energy?

Accepted Answer

MgO

Question 12

A buffer solution is prepared by mixing 0.30 mol of acetic acid (Ka = 1.8 × 10⁻⁵) with 0.20 mol of sodium acetate in 1.0 L of solution. What is the pH of this buffer?

Accepted Answer

4.56

Question 13

Which statement about the photoelectric effect supports the particle nature of light?

Accepted Answer

Below a threshold frequency, no electrons are emitted regardless of intensity

Question 14

In the reaction 2NO(g) + O₂(g) → 2NO₂(g), if NO is consumed at a rate of 0.040 M/s, at what rate is NO₂ being produced?

Accepted Answer

0.040 M/s

Question 15

Which of the following molecules is polar?

Accepted Answer

SF₄

Question 16

What is the oxidation state of chromium in K₂Cr₂O₇?

Accepted Answer

+6

Question 17

The solubility product constant (Ksp) for PbCl₂ is 1.7 × 10⁻⁵. What is the molar solubility of PbCl₂ in pure water?

Accepted Answer

1.6 × 10⁻² M

Question 18

Which of the following represents the correct order of increasing atomic radius?

Accepted Answer

Si < Al < Mg < Na

Question 19

For the reaction A + B → C, the following data were collected:

Experiment 1: [A] = 0.10 M, [B] = 0.10 M, Rate = 2.0 × 10⁻³ M/s
Experiment 2: [A] = 0.20 M, [B] = 0.10 M, Rate = 8.0 × 10⁻³ M/s
Experiment 3: [A] = 0.10 M, [B] = 0.20 M, Rate = 2.0 × 10⁻³ M/s

What is the rate law for this reaction?

Accepted Answer

Rate = k[A]²

Question 20

Which of the following statements about entropy is correct?

Accepted Answer

The entropy of a perfect crystal at 0 K is zero