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# HESI A2 CHEMISTRY PRACTICE TEST
## COMPREHENSIVE QUESTION BANK (250+
QUESTIONS)
### 2026-2027 EDITION | BASED ON ELSEVIER
EVOLVE & ATI TESTING STANDARDS
## SECTION 1: ATOMIC STRUCTURE & PROPERTIES
### Questions 1-25
**Question 1**
Which subatomic particle carries a negative charge?
A) Proton
B) Neutron
C) Electron
D) Nucleus
**Correct Answer: C**
**Rationale:** Electrons carry a negative charge (-1). Protons are positive (+1),
and neutrons are neutral (0). Understanding electron charge is fundamental to
grasping chemical bonding and electricity in the body .
---
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**Question 2**
What is the atomic number of an element?
A) Number of neutrons
B) Number of protons
C) Number of protons and neutrons
D) Number of protons, neutrons, and electrons
**Correct Answer: B**
**Rationale:** The atomic number equals the number of protons in the nucleus of
an atom. This number defines the element and determines its position on the
periodic table. For a neutral atom, the number of electrons equals the number of
protons .
---
**Question 3**
An atom has 17 protons and 18 neutrons. What is the mass number?
A) 17
B) 35
C) 18
D) 1
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**Correct Answer: B**
**Rationale:** Mass number = protons + neutrons = 17 + 18 = 35. The mass
number represents the total number of nucleons in the nucleus and is used to
distinguish isotopes of an element .
---
**Question 4**
How many neutrons does carbon-14 have? (Carbon atomic number = 6)
A) 6
B) 14
C) 8
D) 20
**Correct Answer: C**
**Rationale:** Mass number - atomic number = neutrons. 14 - 6 = 8 neutrons.
Carbon-14 is a radioactive isotope used in medical diagnostics .
---
**Question 5**
Which particle primarily determines an element's mass number?
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A) Electron
B) Proton and neutron
C) Proton only
D) Neutron only
**Correct Answer: B**
**Rationale:** Mass number is the sum of protons and neutrons in the nucleus.
Electrons have negligible mass (approximately 1/1836 of a proton) and do not
significantly contribute to the mass number .
---
**Question 6**
What is the electron configuration of oxygen (atomic number 8)?
A) 1s² 2s² 2p⁴
B) 1s² 2s² 2p⁶
C) 1s² 2s² 2p²
D) 1s² 2s²
**Correct Answer: A**
# HESI A2 CHEMISTRY PRACTICE TEST
## COMPREHENSIVE QUESTION BANK (250+
QUESTIONS)
### 2026-2027 EDITION | BASED ON ELSEVIER
EVOLVE & ATI TESTING STANDARDS
## SECTION 1: ATOMIC STRUCTURE & PROPERTIES
### Questions 1-25
**Question 1**
Which subatomic particle carries a negative charge?
A) Proton
B) Neutron
C) Electron
D) Nucleus
**Correct Answer: C**
**Rationale:** Electrons carry a negative charge (-1). Protons are positive (+1),
and neutrons are neutral (0). Understanding electron charge is fundamental to
grasping chemical bonding and electricity in the body .
---
,2|Page
**Question 2**
What is the atomic number of an element?
A) Number of neutrons
B) Number of protons
C) Number of protons and neutrons
D) Number of protons, neutrons, and electrons
**Correct Answer: B**
**Rationale:** The atomic number equals the number of protons in the nucleus of
an atom. This number defines the element and determines its position on the
periodic table. For a neutral atom, the number of electrons equals the number of
protons .
---
**Question 3**
An atom has 17 protons and 18 neutrons. What is the mass number?
A) 17
B) 35
C) 18
D) 1
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**Correct Answer: B**
**Rationale:** Mass number = protons + neutrons = 17 + 18 = 35. The mass
number represents the total number of nucleons in the nucleus and is used to
distinguish isotopes of an element .
---
**Question 4**
How many neutrons does carbon-14 have? (Carbon atomic number = 6)
A) 6
B) 14
C) 8
D) 20
**Correct Answer: C**
**Rationale:** Mass number - atomic number = neutrons. 14 - 6 = 8 neutrons.
Carbon-14 is a radioactive isotope used in medical diagnostics .
---
**Question 5**
Which particle primarily determines an element's mass number?
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A) Electron
B) Proton and neutron
C) Proton only
D) Neutron only
**Correct Answer: B**
**Rationale:** Mass number is the sum of protons and neutrons in the nucleus.
Electrons have negligible mass (approximately 1/1836 of a proton) and do not
significantly contribute to the mass number .
---
**Question 6**
What is the electron configuration of oxygen (atomic number 8)?
A) 1s² 2s² 2p⁴
B) 1s² 2s² 2p⁶
C) 1s² 2s² 2p²
D) 1s² 2s²
**Correct Answer: A**
