1|Page
HESI A2 CHEMISTRY ACTUAL EXAM
2026 | 150 QUESTIONS AND CORRECT
DETAILED ANSWERS WITH
RATIONALE | ALREADY A GRADED |
ALREADY A GRADED | NEW AND
REVISED
This exam is a comprehensive, exam-ready assessment designed to
mirror the structure, rigor, and content distribution of the official HESI
A2 Chemistry examination. It evaluates foundational chemical
principles, applied problem-solving, and healthcare-relevant scenarios
commonly encountered in nursing and allied health education. The
assessment emphasizes critical reasoning, quantitative calculations,
laboratory safety, professional standards, and real-world clinical
applications of chemistry. Questions range from basic recall to complex
application and interpretation, ensuring readiness for both academic
progression and standardized testing success.
1. Which subatomic particle primarily determines the chemical
identity of an element?
A. Neutron
B. Proton
C. Electron
D. Isotope
The number of protons (atomic number) defines the element.
2. A neutral atom of sodium has 11 protons. How many electrons
does it contain?
A. 10
B. 11
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C. 12
D. 23
Neutral atoms have equal numbers of protons and electrons.
3. Which type of bond involves the sharing of electrons?
A. Ionic
B. Covalent
C. Hydrogen
D. Metallic
Covalent bonds form when electrons are shared between atoms.
4. Oxygen has an atomic number of 8 and a mass number of 16. How
many neutrons does it have?
A. 6
B. 8
C. 8
D. 16
Neutrons = mass number − atomic number.
5. Which state of matter has a definite volume but no definite shape?
A. Solid
B. Liquid
C. Gas
D. Plasma
Liquids conform to the shape of their container but maintain
volume.
6. A nurse prepares saline using NaCl dissolved in water. This
mixture is best described as a:
A. Suspension
B. Colloid
C. Solution
D. Compound
A solution is a homogeneous mixture.
7. What is the pH of a neutral solution at 25°C?
A. 0
B. 1
C. 7
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D. 14
Pure water has a pH of 7 at standard conditions.
8. Which substance is a strong acid?
A. Acetic acid
B. Carbonic acid
C. Hydrochloric acid
D. Ammonia
Strong acids fully dissociate in water.
9. The periodic table is arranged primarily by increasing:
A. Atomic mass
B. Atomic number
C. Density
D. Valence electrons
Modern periodic law orders elements by atomic number.
10. Which unit is used to measure temperature in the SI system?
A. Celsius
B. Fahrenheit
C. Kelvin
D. Joule
Kelvin is the SI base unit for temperature.
11. A reaction that releases heat is classified as:
A. Endothermic
B. Exothermic
C. Isothermal
D. Neutral
Exothermic reactions release energy to surroundings.
12. Which gas law states that pressure and volume are inversely
related at constant temperature?
A. Charles’s Law
B. Boyle’s Law
C. Avogadro’s Law
D. Dalton’s Law
Boyle’s Law describes inverse pressure–volume relationships.
13. The molar mass of water (H₂O) is approximately:
A. 2 g/mol
HESI A2 CHEMISTRY ACTUAL EXAM
2026 | 150 QUESTIONS AND CORRECT
DETAILED ANSWERS WITH
RATIONALE | ALREADY A GRADED |
ALREADY A GRADED | NEW AND
REVISED
This exam is a comprehensive, exam-ready assessment designed to
mirror the structure, rigor, and content distribution of the official HESI
A2 Chemistry examination. It evaluates foundational chemical
principles, applied problem-solving, and healthcare-relevant scenarios
commonly encountered in nursing and allied health education. The
assessment emphasizes critical reasoning, quantitative calculations,
laboratory safety, professional standards, and real-world clinical
applications of chemistry. Questions range from basic recall to complex
application and interpretation, ensuring readiness for both academic
progression and standardized testing success.
1. Which subatomic particle primarily determines the chemical
identity of an element?
A. Neutron
B. Proton
C. Electron
D. Isotope
The number of protons (atomic number) defines the element.
2. A neutral atom of sodium has 11 protons. How many electrons
does it contain?
A. 10
B. 11
,2|Page
C. 12
D. 23
Neutral atoms have equal numbers of protons and electrons.
3. Which type of bond involves the sharing of electrons?
A. Ionic
B. Covalent
C. Hydrogen
D. Metallic
Covalent bonds form when electrons are shared between atoms.
4. Oxygen has an atomic number of 8 and a mass number of 16. How
many neutrons does it have?
A. 6
B. 8
C. 8
D. 16
Neutrons = mass number − atomic number.
5. Which state of matter has a definite volume but no definite shape?
A. Solid
B. Liquid
C. Gas
D. Plasma
Liquids conform to the shape of their container but maintain
volume.
6. A nurse prepares saline using NaCl dissolved in water. This
mixture is best described as a:
A. Suspension
B. Colloid
C. Solution
D. Compound
A solution is a homogeneous mixture.
7. What is the pH of a neutral solution at 25°C?
A. 0
B. 1
C. 7
, 3|Page
D. 14
Pure water has a pH of 7 at standard conditions.
8. Which substance is a strong acid?
A. Acetic acid
B. Carbonic acid
C. Hydrochloric acid
D. Ammonia
Strong acids fully dissociate in water.
9. The periodic table is arranged primarily by increasing:
A. Atomic mass
B. Atomic number
C. Density
D. Valence electrons
Modern periodic law orders elements by atomic number.
10. Which unit is used to measure temperature in the SI system?
A. Celsius
B. Fahrenheit
C. Kelvin
D. Joule
Kelvin is the SI base unit for temperature.
11. A reaction that releases heat is classified as:
A. Endothermic
B. Exothermic
C. Isothermal
D. Neutral
Exothermic reactions release energy to surroundings.
12. Which gas law states that pressure and volume are inversely
related at constant temperature?
A. Charles’s Law
B. Boyle’s Law
C. Avogadro’s Law
D. Dalton’s Law
Boyle’s Law describes inverse pressure–volume relationships.
13. The molar mass of water (H₂O) is approximately:
A. 2 g/mol
