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100+ Free AP Chemistry Practice Questions

Pass your AP Chemistry (Advanced Placement Chemistry) exam on the first try — instant access, no signup required.

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The solubility product expression for the dissolution Ca(OH)2(s) <-> Ca2+(aq) + 2 OH-(aq) is which of the following?

A
B
C
D
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Key Facts: AP Chemistry Exam

60

multiple-choice questions in Section I (1 hour 30 minutes)

College Board CED

7

free-response questions in Section II (1 hour 45 minutes)

College Board CED

9

units of course content, from atomic structure to electrochemistry

College Board CED

18-22%

exam weight of Unit 3, Properties of Substances and Mixtures (the highest)

College Board CED

1-5

AP score scale; a 3 or higher typically earns college credit

College Board

$99

standard US exam fee per AP exam for 2025-26

College Board

The AP Chemistry exam runs 3 hours 15 minutes and has two equally weighted sections: 60 multiple-choice questions in 1 hour 30 minutes and 7 free-response questions in 1 hour 45 minutes. Course content spans 9 units, with Unit 3 (Properties of Substances and Mixtures) the most heavily weighted at 18-22%, followed by Unit 8 (Acids and Bases) at 11-15%. Scores range from 1 to 5, and a 3 or higher generally qualifies for college credit. The standard US exam fee is $99 (source: College Board, apstudents.collegeboard.org).

Sample AP Chemistry Practice Questions

Try these sample questions to test your AP Chemistry exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1A 36.0 g sample of pure water (molar mass 18.0 g/mol) is completely vaporized. How many moles of water molecules are present in the sample?
A.1.0 mol
B.36.0 mol
C.0.50 mol
D.2.0 mol
Explanation: Moles equal mass divided by molar mass: 36.0 g / 18.0 g/mol = 2.0 mol. The number of moles is unchanged by vaporization because phase changes do not alter the amount of substance, only its physical state.
2In a mass spectrum, an element shows two peaks: mass 10 (relative abundance 20%) and mass 11 (relative abundance 80%). What is the approximate average atomic mass of this element?
A.10.2
B.10.5
C.10.8
D.11.0
Explanation: Average atomic mass is the weighted average of isotope masses: (0.20)(10) + (0.80)(11) = 2.0 + 8.8 = 10.8. This matches boron, whose two isotopes are boron-10 and boron-11.
3Which ground-state electron configuration correctly represents a neutral chlorine atom (Z = 17)?
A.1s2 2s2 2p6 3s2 3p5
B.1s2 2s2 2p6 3s2 3p6
C.1s2 2s2 2p6 3s2 3p3
D.1s2 2s2 2p5 3s2 3p6
Explanation: Chlorine has 17 electrons. Filling orbitals in order of increasing energy gives 1s2 2s2 2p6 3s2 3p5, which accounts for exactly 17 electrons and leaves one vacancy in the 3p subshell.
4A photoelectron spectrum (PES) of a neutral element shows three peaks corresponding to the 1s, 2s, and 2p subshells, with relative peak heights of 2 : 2 : 6. Which element does this spectrum represent?
A.Carbon
B.Oxygen
C.Neon
D.Nitrogen
Explanation: PES peak heights are proportional to the number of electrons in each subshell. Heights of 2, 2, and 6 give 2 + 2 + 6 = 10 electrons total, matching the configuration 1s2 2s2 2p6, which is neon.
5As you move from left to right across a period in the periodic table, what generally happens to atomic radius and why?
A.It increases because more electron shells are added
B.It decreases because electrons are removed from the atom
C.It stays constant because the number of shells is unchanged
D.It decreases because the increasing nuclear charge pulls electrons closer
Explanation: Across a period, protons are added to the nucleus while electrons fill the same principal shell. The growing effective nuclear charge pulls the electron cloud inward, so atomic radius decreases left to right.
6According to Coulomb's law, the attraction between a nucleus and an electron increases when which of the following occurs?
A.The distance between the charges increases
B.The magnitude of the nuclear charge decreases
C.The magnitude of the nuclear charge increases and the distance decreases
D.Both charges become smaller and farther apart
Explanation: Coulombic attraction is proportional to the product of the charge magnitudes and inversely proportional to the square of the distance between them. Greater nuclear charge and smaller separation both strengthen the attraction.
7Which of the following correctly ranks the first ionization energies from lowest to highest?
A.Na < Mg < Cl
B.Cl < Mg < Na
C.Mg < Na < Cl
D.Cl < Na < Mg
Explanation: First ionization energy generally increases across a period due to rising effective nuclear charge. For these third-period elements, sodium has the lowest, magnesium is higher, and chlorine is highest, giving Na < Mg < Cl.
8A compound is found to contain 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is its empirical formula? (C = 12, H = 1, O = 16)
A.CHO
B.CH2O
C.C2H4O2
D.CHO2
Explanation: Dividing each percentage by its atomic mass gives moles: C = 40.0/12 = 3.33, H = 6.7/1 = 6.7, O = 53.3/16 = 3.33. Dividing by the smallest (3.33) yields a 1:2:1 ratio, so the empirical formula is CH2O.
9In a photoelectron spectrum, the peak corresponding to the 1s electrons of an element appears at a much higher binding energy than the 2s peak. What does this difference indicate?
A.1s electrons are farther from the nucleus than 2s electrons
B.Binding energy is unrelated to how tightly electrons are held
C.2s electrons have a higher principal quantum number error and do not exist
D.1s electrons are held more tightly because they are closer to the nucleus and less shielded
Explanation: Binding energy reflects how tightly an electron is held. The 1s electrons are closest to the nucleus and experience the least shielding, so they require the most energy to remove, producing a peak at higher binding energy than the 2s electrons.
10Which statement best explains why the second ionization energy of sodium is much larger than its first ionization energy?
A.The second electron removed comes from a stable, lower-energy noble gas core
B.Sodium has no second electron to remove
C.The second ionization releases energy rather than requiring it
D.Removing a second electron is always equal in energy to the first
Explanation: Sodium's first ionization removes its single 3s valence electron, leaving a neon-like noble gas core. The second ionization must remove an electron from this very stable, tightly held inner shell, requiring a dramatically larger energy input.

About the AP Chemistry Exam

AP Chemistry is a college-level introductory chemistry course and exam administered by the College Board. The exam has two sections: Section I is 60 multiple-choice questions in 1 hour 30 minutes (50% of the score), taken in the Bluebook app, and Section II is 7 free-response questions in 1 hour 45 minutes (50% of the score), written by hand. Content is organized into 9 units, and a scientific or graphing calculator is permitted throughout the exam.

Questions

60 scored questions

Time Limit

3 hours 15 minutes

Passing Score

Scored 1-5; a 3 or higher typically earns college credit

Exam Fee

$99 per exam (College Board)

AP Chemistry Exam Content Outline

7-9%

Unit 1: Atomic Structure and Properties

Moles, mass spectroscopy, electron configuration, PES, periodic trends, and Coulombic attraction.

7-9%

Unit 2: Compound Structure and Properties

Bonding types, Lewis structures, VSEPR, hybridization, polarity, and resonance.

18-22%

Unit 3: Properties of Substances and Mixtures

Intermolecular forces, gas laws, solutions, separations, and spectroscopy.

7-9%

Unit 4: Chemical Reactions

Net ionic equations, stoichiometry, reaction types, and redox.

7-9%

Unit 5: Kinetics

Rate laws, integrated rate laws, mechanisms, and catalysis.

7-9%

Unit 6: Thermochemistry

Calorimetry, enthalpy, Hess's law, and enthalpy of formation.

7-9%

Unit 7: Equilibrium

K and Q, Le Chatelier's principle, and Ksp.

11-15%

Unit 8: Acids and Bases

pH/pOH, Ka/Kb, buffers, titrations, and pH curves.

7-9%

Unit 9: Thermodynamics and Electrochemistry

Entropy, Gibbs free energy, electrochemical cells, and the Nernst equation.

How to Pass the AP Chemistry Exam

What You Need to Know

  • Passing score: Scored 1-5; a 3 or higher typically earns college credit
  • Exam length: 60 questions
  • Time limit: 3 hours 15 minutes
  • Exam fee: $99 per exam

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

AP Chemistry Study Tips from Top Performers

1Prioritize Unit 3 (18-22%) and Unit 8 (11-15%): together with equilibrium they drive the largest share of MCQ points.
2Practice particulate (particle-level) drawings - the exam frequently asks you to reason from models of atoms, molecules, and intermolecular forces.
3Be fluent with the equilibrium toolkit: set up ICE tables, compare Q to K, and apply Le Chatelier's principle quickly.
4Memorize the strong acids and strong bases so you can immediately classify weak vs strong in acid-base problems.
5Use the provided constants and equations sheet during practice so you know exactly what is given and what you must recall.

Frequently Asked Questions

How many questions are on the AP Chemistry exam and how long is it?

The AP Chemistry exam is 3 hours 15 minutes. Section I has 60 multiple-choice questions in 1 hour 30 minutes (50% of the score), and Section II has 7 free-response questions in 1 hour 45 minutes (50% of the score).

How is the AP Chemistry exam scored?

AP Chemistry is scored on a 1-5 scale. A score of 3 is considered qualified, and many colleges grant credit or placement for a 3, 4, or 5, though policies vary by institution.

What are the 9 units of AP Chemistry?

The 9 units are Atomic Structure and Properties; Compound Structure and Properties; Properties of Substances and Mixtures; Chemical Reactions; Kinetics; Thermochemistry; Equilibrium; Acids and Bases; and Thermodynamics and Electrochemistry.

Which AP Chemistry unit is weighted the most on the exam?

Unit 3, Properties of Substances and Mixtures, is the most heavily weighted at 18-22% of the multiple-choice section, followed by Unit 8, Acids and Bases, at 11-15%.

Can I use a calculator on the AP Chemistry exam?

Yes. A scientific or graphing calculator is permitted on both the multiple-choice and free-response sections, and a periodic table and a formula/constants sheet are provided.

How much does the AP Chemistry exam cost?

The standard exam fee is $99 per exam in the US, US territories, Canada, and DoDEA schools. Fee reductions of $37 are available for students with financial need.