CHEMISTRYASSMT096(
7712) Practice
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Rationale 2026 2027
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1. Which subatomic particle has a negative charge?
A. Proton
B. Neutron
C. Electron
D. Nucleus
Answer: C. Electron
,Rationale: Electrons carry a negative electrical charge, whereas
protons are positive and neutrons have no charge.
2. Which subatomic particle determines the atomic number of an
element?
A. Electron
B. Neutron
C. Proton
D. Nucleon
Answer: C. Proton
Rationale: The atomic number equals the number of protons in the
nucleus.
3. An atom contains 11 protons and 12 neutrons. What is its mass
number?
A. 11
B. 12
C. 22
D. 23
Answer: D. 23
Rationale: Mass number = protons + neutrons = 11 + 12 = 23.
4. What is the atomic number of sodium?
A. 10
B. 11
C. 12
D. 23
,Answer: B. 11
Rationale: Sodium has 11 protons and therefore has an atomic
number of 11.
5. Isotopes of the same element differ in their number of:
A. Protons
B. Electrons
C. Neutrons
D. Valence shells
Answer: C. Neutrons
Rationale: Isotopes have the same number of protons but different
numbers of neutrons.
6. Which principle states that electrons occupy the lowest-energy
orbitals available before higher-energy orbitals?
A. Hund's rule
B. Heisenberg principle
C. Aufbau principle
D. Octet rule
Answer: C. Aufbau principle
Rationale: The Aufbau principle describes the progressive filling of
orbitals from lower to higher energy.
7. How many electrons can occupy an s orbital?
A. 1
B. 2
, C. 6
D. 10
Answer: B. 2
Rationale: Every atomic orbital can contain a maximum of two
electrons with opposite spins.
8. How many electrons can occupy a p subshell?
A. 2
B. 4
C. 6
D. 8
Answer: C. 6
Rationale: A p subshell contains three orbitals, each capable of
holding two electrons.
9. Which element has the electron configuration 1s²2s²2p⁶?
A. Oxygen
B. Fluorine
C. Neon
D. Sodium
Answer: C. Neon
Rationale: The configuration contains 10 electrons, corresponding to
neon.
10. Which element is the most electronegative?
A. Oxygen
B. Chlorine
7712) Practice
Questions And Correct
Answers (Verified
Answers) Plus
Rationale 2026 2027
Q&A| Instant
Download Pdf.
1. Which subatomic particle has a negative charge?
A. Proton
B. Neutron
C. Electron
D. Nucleus
Answer: C. Electron
,Rationale: Electrons carry a negative electrical charge, whereas
protons are positive and neutrons have no charge.
2. Which subatomic particle determines the atomic number of an
element?
A. Electron
B. Neutron
C. Proton
D. Nucleon
Answer: C. Proton
Rationale: The atomic number equals the number of protons in the
nucleus.
3. An atom contains 11 protons and 12 neutrons. What is its mass
number?
A. 11
B. 12
C. 22
D. 23
Answer: D. 23
Rationale: Mass number = protons + neutrons = 11 + 12 = 23.
4. What is the atomic number of sodium?
A. 10
B. 11
C. 12
D. 23
,Answer: B. 11
Rationale: Sodium has 11 protons and therefore has an atomic
number of 11.
5. Isotopes of the same element differ in their number of:
A. Protons
B. Electrons
C. Neutrons
D. Valence shells
Answer: C. Neutrons
Rationale: Isotopes have the same number of protons but different
numbers of neutrons.
6. Which principle states that electrons occupy the lowest-energy
orbitals available before higher-energy orbitals?
A. Hund's rule
B. Heisenberg principle
C. Aufbau principle
D. Octet rule
Answer: C. Aufbau principle
Rationale: The Aufbau principle describes the progressive filling of
orbitals from lower to higher energy.
7. How many electrons can occupy an s orbital?
A. 1
B. 2
, C. 6
D. 10
Answer: B. 2
Rationale: Every atomic orbital can contain a maximum of two
electrons with opposite spins.
8. How many electrons can occupy a p subshell?
A. 2
B. 4
C. 6
D. 8
Answer: C. 6
Rationale: A p subshell contains three orbitals, each capable of
holding two electrons.
9. Which element has the electron configuration 1s²2s²2p⁶?
A. Oxygen
B. Fluorine
C. Neon
D. Sodium
Answer: C. Neon
Rationale: The configuration contains 10 electrons, corresponding to
neon.
10. Which element is the most electronegative?
A. Oxygen
B. Chlorine
