HESI A2 CHEMISTRY PRACTICE TEST 2026 ACTUAL QUESTIONS AND ANSWERS ALREADY GRADED A+. 100%
VERIFIED SOLUTIONS | UPDATED PER LATEST GUIDELINES | GRADED A+
Question 1
What is the atomic number of an element that has 14 protons and 14 neutrons?
A. 14
B. 28
C. 7
D. 42
🟢 Correct Answer:
A. 14
🔴 RATIONALE:
The atomic number is defined as the number of protons in the nucleus of an atom. This element has 14 protons,
so its atomic number is 14. The mass number is the sum of protons and neutrons (14 + 14 = 28), which is
different from the atomic number. The number of protons determines the element's identity.
Question 2
Which of the following is the correct electron configuration for oxygen (atomic number 8)?
A. 1s² 2s² 2p⁴
B. 1s² 2s² 2p⁶
,C. 1s² 2s² 2p²
D. 1s² 2s² 2p⁶ 3s²
🟢 Correct Answer:
A. 1s² 2s² 2p⁴
🔴 RATIONALE:
Oxygen has 8 electrons. The electron configuration is filled in order of increasing energy levels: 1s² (2 electrons),
2s² (2 electrons), and 2p⁴ (4 electrons), totaling 8 electrons. Option B is the configuration for neon (10
electrons), and option D is for magnesium (12 electrons).
Question 3
What is the name of the compound NaCl?
A. Sodium chloride
B. Sodium chlorate
C. Sodium chlorite
D. Sodium perchlorate
🟢 Correct Answer:
A. Sodium chloride
🔴 RATIONALE:
NaCl is an ionic compound composed of sodium (Na⁺) and chloride (Cl⁻) ions. The correct name is sodium
chloride, which is common table salt. Sodium chlorate is NaClO₃, sodium chlorite is NaClO₂, and sodium
perchlorate is NaClO₄.
,Question 4
Which of the following is a physical change?
A. Burning wood
B. Rusting of iron
C. Boiling water
D. Digesting food
🟢 Correct Answer:
C. Boiling water
🔴 RATIONALE:
Boiling water is a physical change because it involves a change of state from liquid to gas without altering the
chemical composition of water (H₂O). Burning wood, rusting iron, and digesting food are all chemical changes
because new substances are formed with different chemical properties.
Question 5
What is the molar mass of water (H₂O)? (H = 1 g/mol, O = 16 g/mol)
A. 17 g/mol
B. 18 g/mol
C. 20 g/mol
D. 16 g/mol
, 🟢 Correct Answer:
B. 18 g/mol
🔴 RATIONALE:
The molar mass of water is calculated by adding the atomic masses of its constituent atoms: 2 hydrogen atoms
(2 × 1 g/mol = 2 g/mol) + 1 oxygen atom (16 g/mol) = 18 g/mol. This is the mass of one mole of water
molecules.
Question 6
Which type of bond involves the sharing of electrons between atoms?
A. Ionic bond
B. Covalent bond
C. Metallic bond
D. Hydrogen bond
🟢 Correct Answer:
B. Covalent bond
🔴 RATIONALE:
A covalent bond involves the sharing of electron pairs between atoms, typically between nonmetals. Ionic
bonds involve the transfer of electrons from one atom to another, forming ions. Metallic bonds involve a "sea"
of delocalized electrons. Hydrogen bonds are weaker intermolecular forces.
VERIFIED SOLUTIONS | UPDATED PER LATEST GUIDELINES | GRADED A+
Question 1
What is the atomic number of an element that has 14 protons and 14 neutrons?
A. 14
B. 28
C. 7
D. 42
🟢 Correct Answer:
A. 14
🔴 RATIONALE:
The atomic number is defined as the number of protons in the nucleus of an atom. This element has 14 protons,
so its atomic number is 14. The mass number is the sum of protons and neutrons (14 + 14 = 28), which is
different from the atomic number. The number of protons determines the element's identity.
Question 2
Which of the following is the correct electron configuration for oxygen (atomic number 8)?
A. 1s² 2s² 2p⁴
B. 1s² 2s² 2p⁶
,C. 1s² 2s² 2p²
D. 1s² 2s² 2p⁶ 3s²
🟢 Correct Answer:
A. 1s² 2s² 2p⁴
🔴 RATIONALE:
Oxygen has 8 electrons. The electron configuration is filled in order of increasing energy levels: 1s² (2 electrons),
2s² (2 electrons), and 2p⁴ (4 electrons), totaling 8 electrons. Option B is the configuration for neon (10
electrons), and option D is for magnesium (12 electrons).
Question 3
What is the name of the compound NaCl?
A. Sodium chloride
B. Sodium chlorate
C. Sodium chlorite
D. Sodium perchlorate
🟢 Correct Answer:
A. Sodium chloride
🔴 RATIONALE:
NaCl is an ionic compound composed of sodium (Na⁺) and chloride (Cl⁻) ions. The correct name is sodium
chloride, which is common table salt. Sodium chlorate is NaClO₃, sodium chlorite is NaClO₂, and sodium
perchlorate is NaClO₄.
,Question 4
Which of the following is a physical change?
A. Burning wood
B. Rusting of iron
C. Boiling water
D. Digesting food
🟢 Correct Answer:
C. Boiling water
🔴 RATIONALE:
Boiling water is a physical change because it involves a change of state from liquid to gas without altering the
chemical composition of water (H₂O). Burning wood, rusting iron, and digesting food are all chemical changes
because new substances are formed with different chemical properties.
Question 5
What is the molar mass of water (H₂O)? (H = 1 g/mol, O = 16 g/mol)
A. 17 g/mol
B. 18 g/mol
C. 20 g/mol
D. 16 g/mol
, 🟢 Correct Answer:
B. 18 g/mol
🔴 RATIONALE:
The molar mass of water is calculated by adding the atomic masses of its constituent atoms: 2 hydrogen atoms
(2 × 1 g/mol = 2 g/mol) + 1 oxygen atom (16 g/mol) = 18 g/mol. This is the mass of one mole of water
molecules.
Question 6
Which type of bond involves the sharing of electrons between atoms?
A. Ionic bond
B. Covalent bond
C. Metallic bond
D. Hydrogen bond
🟢 Correct Answer:
B. Covalent bond
🔴 RATIONALE:
A covalent bond involves the sharing of electron pairs between atoms, typically between nonmetals. Ionic
bonds involve the transfer of electrons from one atom to another, forming ions. Metallic bonds involve a "sea"
of delocalized electrons. Hydrogen bonds are weaker intermolecular forces.
