HESI A2 Chemistry Practice Test: Free Timed Drill

What is on the HESI A2 Chemistry section?

About 30 questions in 25 minutes, 25 or so scored, on 7 topics: matter and its changes, atomic structure, the periodic table, bonding, reactions and equations, solutions, acids and bases, nuclear and organic basics.

HESI A2 Chemistry, as schools describe it, with where each fact comes from
Questions	30 shown, about 25 scored; the unscored pilot questions look the sameReportedGateway Technical College, HESI A2 testing (questions and minutes per section)
Time	25 minutes on this section's own clockReportedGateway Technical College, HESI A2 testing (questions and minutes per section)
Even pace	About 50 seconds a question (25 × 60 ÷ 30)LifeScore
Scoring	Percent correct for the section, shown on your score report with a cumulative scoreReportedCentral Texas College, HESI A2 information sheet (on-screen calculator, score report)
Required?	Only if your program lists it: each program picks the sections and sets the minimumReportedChamberlain University, HESI Admission Assessment (A2) exam FAQs
In our full mock	6 questions in 6 minutes, the same pace on a shorter sectionLifeScore

Elsevier does not publish one public spec sheet for the HESI A2, so the question counts and times here are the ones schools publish for their own candidates, labelled Reported. On 20 October 2026 our build environment could not open Elsevier's or most schools' pages directly, so each was read through search-result text from the named page. Your program's own testing page always wins.

What does each HESI Chemistry topic ask?

Seven topics; atomic structure, reactions and acids and bases account for the largest share.

The topics follow the chapters of Elsevier's Admission Assessment Exam Review. "What it covers" is the content; "how it reads" is our description of the questions you will meet, from writing and checking hundreds of them.

Matter and its changes
What it covers: States of matter, physical and chemical changes, mixtures and compounds, gas laws.
How it reads: Is ice melting a physical change? What happens to pressure when volume halves?
Atomic structure
What it covers: Protons, neutrons and electrons, atomic number, mass number, isotopes and ions.
How it reads: How many neutrons are in chlorine-37?
The periodic table
What it covers: Groups and periods, valence electrons, trends in radius and electronegativity, symbols.
How it reads: Which group holds the noble gases? What is the symbol for potassium?
Bonding
What it covers: Ionic, covalent and hydrogen bonds; polarity.
How it reads: Which pair forms an ionic bond?
Reactions and equations
What it covers: Balancing, reaction types, rates, catalysts and equilibrium.
How it reads: Balance N₂ + H₂ → NH₃. Name a single replacement reaction.
Solutions, acids and bases
What it covers: Solute and solvent, molarity, dilution, pH, buffers and neutralization.
How it reads: What is the molarity of 0.5 mol in 250 mL? Is pH 3 acidic?
Nuclear and organic basics
What it covers: Alpha, beta and gamma radiation, half-life, fusion and fission, and carbon compounds.
How it reads: How much of a sample remains after three half-lives?

What do HESI A2 Chemistry questions look like?

Three original questions: neutrons in an isotope, a balanced equation and a molarity calculation, each worked.

Try each one before you open the answer. They are original, written by us in the HESI A2 style, and are not real HESI items or questions from our mocks. The first is worked open.

HESI A2-style question 1 · Atomic structure
How many neutrons are in an atom of chlorine-37? (Chlorine's atomic number is 17.)
1. A17
2. B20
3. C37
4. D54
Worked answer
B: 20. Neutrons = mass number − atomic number = 37 − 17 = 20.
1. The number after the name is the mass number: 37 (protons + neutrons).
2. The atomic number is the protons: 17.
3. 37 − 17 = 20 neutrons.
The trap: Giving the atomic number (17) or adding the two numbers (54).
HESI A2-style question 2 · Equations
Which coefficients balance the equation ___ Al + ___ O₂ → ___ Al₂O₃?
1. A2, 3, 2
2. B2, 3, 1
3. C4, 3, 2
4. D4, 6, 2
Show the worked answer
C: 4, 3, 2. 4 Al + 3 O₂ → 2 Al₂O₃ has 4 aluminum and 6 oxygen atoms on each side.
1. Oxygen: 2 on the left and 3 on the right; the lowest common multiple is 6, so 3 O₂ and 2 Al₂O₃.
2. 2 Al₂O₃ contains 4 aluminum atoms, so 4 Al.
3. Check: Al 4 = 4; O 6 = 6.
The trap: Balancing aluminum first and stopping before checking oxygen on both sides.
HESI A2-style question 3 · Solutions
What is the molarity of a solution made by dissolving 0.5 mol of NaCl in enough water to make 250 mL of solution?
1. A0.5 M
2. B125 M
3. C2 M
4. D0.125 M
Show the worked answer
C: 2 M. Molarity = moles ÷ liters = 0.5 ÷ 0.250 = 2 M.
1. Convert the volume to liters: 250 mL = 0.250 L.
2. Divide moles by liters: 0.5 ÷ 0.25.
3. = 2 mol/L, or 2 M.
The trap: Dividing by 250 instead of 0.250, or multiplying instead of dividing.

Make Chemistry a section you bank

Twelve questions show the gap. 4 more Chemistry drills and 8 full seven-section mocks close it.

The HESI A2 Pass Pack gives you 8 full mocks on the real clock, 28 drills of 12 questions for the sections that cost you points, and a predictor that turns your mocks into the odds of reaching your target. One payment, no subscription, and your free score stays free.

Prep courses for these tests usually cost $19 to $129. The HESI A2 Pass Pack is US$39 (£29), once.

See the HESI A2 Pass Pack How our questions are built and checked

8
timed mocks: 28
topic drills: 1
score predictor

Which chemistry formulas do I need for the HESI A2?

These eight cover every calculation the section is likely to ask. None needs more than two steps.

Our list of the formulas behind HESI-style chemistry calculations
Quantity	Formula	Example
Neutrons	mass number − atomic number	Carbon-14: 14 − 6 = 8
Ion electrons	protons − charge	Mg²⁺: 12 − 2 = 10
Molar mass	sum of atomic masses	H₂O: 2(1) + 16 = 18 g/mol
Moles	mass ÷ molar mass	36 g water ÷ 18 = 2 mol
Molarity	moles ÷ liters of solution	0.5 mol in 0.25 L = 2 M
Dilution	M₁V₁ = M₂V₂	2 M × 50 mL = 0.5 M × 200 mL
pH	−log[H⁺]; each unit is a factor of 10	pH 3 is 100 times more acidic than pH 5
Half-life	amount × (1/2)ⁿ for n half-lives	80 mg after 3 half-lives = 10 mg

Blood pH is 7.35 to 7.45; water boils at 100 °C at sea level; absolute zero is 0 K. These three numbers turn up as quick recall questions.

How should I pace the HESI Chemistry section?

Aim for about 50 seconds a question on average: faster on the questions you know, so the hard ones get the time they need. Use these checkpoints.

Our checkpoints, from the reported 30 questions in 25 minutes
When	Where you should be	What to do
6 minutes in	Question 8	On pace: keep going
13 minutes in	Question 15	Behind by 3 or more? Guess and move on from any question past a minute
19 minutes in	Question 23	Leave the last minutes for a guess on every blank

Split the section in your head: recall questions in 15 to 25 seconds, calculations in 60 to 90. The time saved on recall pays for the calculations.

Write the formula before the numbers. Most calculation errors are a skipped unit conversion (mL to L) rather than bad arithmetic.

A wrong answer and a blank both score zero on a percent-correct score, so never leave a question empty when the clock is about to run out.

What traps cost the most points on HESI Chemistry?

Chemistry misses come from a handful of slips.

Forgetting to convert mL to L in molarity questions.
Treating pH as linear: pH 4 is ten times more acidic than pH 5, not slightly.
Balancing one element and not rechecking the others.
Confusing oxidation (loss of electrons) and reduction (gain). OIL RIG: oxidation is loss, reduction is gain.

How should I study for HESI Chemistry?

Thirty minutes a day for a week: two topics a day, then calculations, then a timed mixed set.

Our plan, with minutes a day

Day 1
25 min
Take the free drill above. Separate recall misses from calculation misses.
Day 2
30 min
Matter, atomic structure and isotopes.
Day 3
30 min
Periodic table and bonding.
Day 4
30 min
Balancing equations and reaction types: balance ten.
Day 5
30 min
Solutions, molarity, dilution and pH: work every formula in the table.
Day 6
30 min
Nuclear chemistry and half-life; then a timed mixed set.
Day 7
20 min
Review only your misses.

How much does Chemistry count for nursing school admission?

Chemistry is required by fewer programs than math or reading, but where it is required it often counts toward a science or cumulative minimum.

FSCJ's dental hygiene program, for example, averages chemistry with reading, vocabulary and anatomy and physiology for a 75% minimum. Check your own program on the HESI A2 passing score page before investing a week here.

The TEAS science section includes a smaller chemistry share; see the TEAS science practice test.

Scores reach your Evolve account within about 24 to 48 hours, with a percentage for each section and a cumulative score. Retake rules are set by each school. Baylor, for example, allows at most three attempts with 60 days between them.

Frequently asked questions

How many questions are on HESI A2 chemistry?

Schools list 30 questions in 25 minutes, with 25 scored.

Is there math on HESI chemistry?

A little: neutrons, molar mass, moles, molarity, dilution, pH and half-life. Each is one or two steps, and a calculator is on screen.

Do all programs require HESI chemistry?

No. Your program chooses the sections. It is more common for RN, BSN and dental hygiene programs.

Is the free chemistry drill the real HESI?

No. It is 12 original HESI A2-style questions at the real section pace. LifeScore is not affiliated with Elsevier.

All seven sections, on the real clocks

8 full HESI A2-style mocks, 28 section drills (4 for Chemistry) and every answer worked, in one payment with no subscription.