HESI A2 Chemistry Exam 2025 | Verified
Questions and 100% Correct Answers for
Guaranteed Success
Section 1: Atomic Structure and Periodic Table (8
Questions)
Question 1: What is the atomic number of nitrogen?
Answer: 7
Rationale: The atomic number equals the number of protons in the nucleus; nitrogen has 7
protons.
Question 2: Which subatomic particle has no charge?
Answer: Neutron
Rationale: Neutrons are neutral, residing in the nucleus, while protons are positive and electrons
negative.
Question 3: How many valence electrons does carbon have?
Answer: 4
Rationale: Carbon is in group 14; valence electrons equal the group number, critical for
bonding.
Question 4: What is the electron configuration of oxygen (atomic number 8)?
Answer: 1s² 2s² 2p⁴
Rationale: Electrons fill orbitals per Aufbau principle: 2 in 1s, 2 in 2s, 4 in 2p.
Question 5: Which element in the same period as sodium has similar chemical properties?
Answer: Potassium
Rationale: Elements in the same group (e.g., group 1: Na, K) have similar properties due to
identical valence electrons.
Question 6: What is the charge of a fluoride ion?
Answer: -1
Rationale: Fluorine gains one electron to achieve a stable octet, forming F⁻.
Question 7: Which property increases across a period in the periodic table?
Answer: Electronegativity
Rationale: Electronegativity increases left to right due to higher nuclear charge attracting
electrons.
Questions and 100% Correct Answers for
Guaranteed Success
Section 1: Atomic Structure and Periodic Table (8
Questions)
Question 1: What is the atomic number of nitrogen?
Answer: 7
Rationale: The atomic number equals the number of protons in the nucleus; nitrogen has 7
protons.
Question 2: Which subatomic particle has no charge?
Answer: Neutron
Rationale: Neutrons are neutral, residing in the nucleus, while protons are positive and electrons
negative.
Question 3: How many valence electrons does carbon have?
Answer: 4
Rationale: Carbon is in group 14; valence electrons equal the group number, critical for
bonding.
Question 4: What is the electron configuration of oxygen (atomic number 8)?
Answer: 1s² 2s² 2p⁴
Rationale: Electrons fill orbitals per Aufbau principle: 2 in 1s, 2 in 2s, 4 in 2p.
Question 5: Which element in the same period as sodium has similar chemical properties?
Answer: Potassium
Rationale: Elements in the same group (e.g., group 1: Na, K) have similar properties due to
identical valence electrons.
Question 6: What is the charge of a fluoride ion?
Answer: -1
Rationale: Fluorine gains one electron to achieve a stable octet, forming F⁻.
Question 7: Which property increases across a period in the periodic table?
Answer: Electronegativity
Rationale: Electronegativity increases left to right due to higher nuclear charge attracting
electrons.
