HESI A2 › § Chemistry
Free HESI A2 Chemistry Practice Questions
The HESI A2 Chemistry subtest is twenty five scored questions in twenty five minutes, drawn from matter and measurement, bonding and reactions, quantitative chemistry, acids and bases, nuclear chemistry, and biochemistry. That is one minute per question, so the seven questions below are timed the same way the real subtest runs.
Every question here is original, written by RedRubric and mapped to the same HESI A2 outline, not lifted from a past paper. Answer each one, then read the rationale even when you get it right. The full chemistry bank sits behind the same mapping, so once these seven feel comfortable you know exactly which topic to open next.
A follow-up arterial blood gas on the same patient later reads pH 7.50. How should this new value be classified?
Select an answer to reveal the explanation.
Correct answer: A, Alkalosis, since the value is above the normal 7.35 to 7.45 range
A pH of 7.50 is above the normal 7.35 to 7.45 range for arterial blood, which places it in the alkalosis category rather than the normal or acidotic range.
The periodic table lists carbon's atomic weight as 12.011 rather than a whole number. Why does the value come out as a decimal?
Select an answer to reveal the explanation.
Correct answer: B, Because the listed value averages the masses of carbon's naturally occurring isotopes, weighted by their abundance
A natural sample of an element is a mixture of isotopes in fixed proportions, so the tabled atomic weight is a weighted average across those isotopes rather than one whole-number mass.
A patient's haemoglobin A1c is ordered to check average blood glucose over the past three months. Chemically, this test is measuring glucose molecules that have become attached to which type of macromolecule?
Select an answer to reveal the explanation.
Correct answer: C, A protein
Haemoglobin A1c reflects glucose that has become non-enzymatically attached to haemoglobin, which is a protein, so the test tracks carbohydrate chemistry acting on a protein molecule.
For the balanced equation 2 C2H6 + 7 O2 → 4 CO2 + 6 H2O, how many moles of oxygen are needed to react completely with 6 moles of ethane (C2H6)?
Select an answer to reveal the explanation.
Correct answer: B, 21 moles
The mole ratio of ethane to oxygen is 2 to 7, so scaling 6 moles of ethane up by a factor of 3 requires 7 times 3, which is 21 moles of oxygen.
Hydrogen and oxygen react by 2H2 + O2 -> 2H2O. A lab technician combines 8 moles of hydrogen gas with 3 moles of oxygen gas. How many moles of water actually form?
Select an answer to reveal the explanation.
Correct answer: A, 6 moles
Oxygen is limiting because 3 moles of O2 can only form 3 times 2 over 1, equal to 6 moles of water, less than the 8 moles that hydrogen alone could support.
A pharmacology calculation multiplies a plasma concentration of 4 x 10^3 ng/mL by a distribution factor of 2 x 10^2. What is the product, written in scientific notation?
Select an answer to reveal the explanation.
Correct answer: D, 8 x 10^5
To multiply numbers written in scientific notation, multiply the leading digits and add the exponents: 4 times 2 equals 8, and 3 plus 2 equals 5, giving 8 x 10^5. Option b adds one extra to the exponent by mistake. Option c adds the leading digits, 4 plus 2, instead of multiplying them. Option a subtracts the exponents instead of adding them.
A nurse has 20 mL of a 10% stock solution and dilutes it to 4%. Using C1V1 = C2V2, what is the final volume of the diluted solution?
Select an answer to reveal the explanation.
Correct answer: A, 50 mL
C1V1 = C2V2 gives 10 times 20 equals 4 times V2, so V2 equals 50 mL, the total final volume.
That is seven of hundreds.
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