HESI A2 chemistry practice questions
- free questions here
- 10 free questions here
- topics covered
- 8 topics covered
- last updated
- October 2026 last updated
Ten free HESI A2 chemistry practice questions are below, each with an explanation. Chemistry is one of the optional science sections; your school decides whether you take it. It covers matter and its states, atomic structure and the periodic table, bonding, balancing equations, moles and stoichiometry, solutions, acids and bases, and oxidation-reduction.
Chemistry
10 free chemistry questions
Answer, check, and read the explanation before you move on.
HESI A2 Chemistry
Question 1 of 10
Which sequence lists the media in order of fastest to slowest diffusion?
Not quite. The answer is D
Key takeaway
Diffusion is fastest in gases, then liquids, then gels, then solids. Particles in gases move most freely. Diffusion in solids is tiny but rises with temperature.
Which species has 20 protons and 18 electrons?
Not quite. The answer is A
Key takeaway
Ionic charge is protons minus electrons, so 20 − 18 = +2, giving Ca²⁺. K⁺ would have 19 protons.
Which of the following correctly describes the directional character of bonding?
Not quite. The answer is B
Key takeaway
Covalent bonds point in specific directions between atoms, while ionic attraction acts in all directions around an ion in the lattice.
Which equation shows the balanced combustion of methane?
Not quite. The answer is C
Key takeaway
Products contain 2 O in CO₂ and 2 O in 2H₂O, a total of 4 O, so 2 O₂ are needed. Hydrogen is 4 on each side.
Molar mass is best defined as the mass of one mole of a substance, expressed in which unit?
Not quite. The answer is B
Key takeaway
Molar mass is grams per mole, g/mol. The amu is the unit for the mass of a single atom or formula unit, not for a mole of it.
A student dissolves 0.01 mol of sugar in 200 mL of tea. What is the molarity of the sugar?
Not quite. The answer is B
Key takeaway
Convert 200 mL to 0.200 L, then M = 0.01 mol / 0.200 L = 0.05 M. Forgetting the mL to L conversion gives 0.00005 or wrong-scale values.
Why is ammonia (NH3) classified as a Brønsted-Lowry base but not an Arrhenius base?
Not quite. The answer is C
Key takeaway
NH3 has no OH- in its formula, so it fails the Arrhenius definition. It accepts H+, which makes it a Brønsted-Lowry base.
In Fe + 2HCl → FeCl2 + H2, which species is the oxidizing agent?
Not quite. The answer is A
Key takeaway
Hydrogen goes from +1 to 0, so it gains electrons and is reduced. The species containing it, HCl, is therefore the oxidizing agent, while Fe is the reducing agent.
Plasma is best described as a gaseous state that contains ________.
Not quite. The answer is D
Key takeaway
Plasma is a gas with appreciable numbers of charged particles. It occurs in stars and lightning strikes.
An atom has mass number 31 and atomic number 15. How many neutrons does it contain?
Not quite. The answer is A
Key takeaway
Neutrons N = A − Z = 31 − 15 = 16. Adding A and Z gives 46, which is the wrong operation.
Coverage
What HESI A2 chemistry covers
The topics our practice questions for this section are written to.
- Describe matter, its states and properties
- Describe atomic structure and the periodic table
- Describe chemical bonding (ionic, covalent, hydrogen bonds)
- Balance chemical equations and identify reaction types
- Perform stoichiometry and mole calculations
- Describe solutions, concentration and solubility
- Describe acids, bases and pH
- Describe oxidation-reduction and basic nuclear chemistry
Tips
How to score higher on chemistry
- Neutrons = mass number minus atomic number. Charge = protons minus electrons.
- Balance equations by counting each element on both sides, leaving hydrogen and oxygen for last.
- Molarity is moles of solute per litre of solution, so convert mL to L first.
- The oxidizing agent is the species that gets reduced.
FAQ
HESI A2 chemistry FAQ
Is chemistry on the HESI A2?
Chemistry is one of the science sections Elsevier offers. Each school decides which sections its applicants take.
What chemistry is on the HESI A2?
Matter, atomic structure and the periodic table, chemical bonding, balancing equations, stoichiometry and moles, solutions, acids and bases, and oxidation-reduction.
How many questions are in HESI A2 chemistry?
We have not found an official count we can cite. Your school or testing center can confirm the section length.
Keep practising HESI A2 chemistry.
A free account opens more practice questions in every section and a full-length mock test.
Free practice questions in every section, plus a free mock test