,CHEM 121 Module 2 Exam Foundations of General
1. Which property of light is defined as the distance between two consecutive peaks of a wave?
A) Frequency
B) Amplitude
C) Wavelength
D) Velocity
Correct Answer: Wavelength
Rationale: Wavelength is the distance between consecutive peaks or troughs of a wave. Frequency is
the number of waves passing a point per unit time. Amplitude is the height of the wave, and velocity
is the speed at which the wave travels. Options A, B, and D describe other wave properties.
2. What is the energy of a photon with a frequency of 5.0 × 10^14 Hz? (h = 6.626 × 10^-34 J·s)
A) 3.3 × 10^-19 J
B) 3.3 × 10^-20 J
C) 1.3 × 10^-48 J
D) 5.0 × 10^-14 J
Correct Answer: 3.3 × 10^-19 J
,Rationale: E = hν = (6.626 × 10^-34 J·s)(5.0 × 10^14 Hz) = 3.3 × 10^-19 J. Option B is off by a factor of
10, option C is an incorrect multiplication, and option D uses the frequency directly as energy. Options
B, C, and D are incorrect.
3. According to the Bohr model, what happens when an electron transitions from a higher energy
level to a lower energy level?
A) A photon is absorbed.
B) A photon is emitted.
C) The electron's mass increases.
D) The electron's charge changes.
Correct Answer: A photon is emitted.
Rationale: In the Bohr model, when an electron drops from a higher energy level to a lower one, the
energy difference is released as a photon. Absorption occurs when an electron moves to a higher
level. Mass and charge do not change during electronic transitions. Options A, C, and D are incorrect.
4. Which quantum number describes the shape of an orbital?
A) Principal quantum number (n)
B) Angular momentum quantum number (l)
C) Magnetic quantum number (ml)
D) Spin quantum number (ms)
, Correct Answer: Angular momentum quantum number (l)
Rationale: The angular momentum quantum number (l) determines the shape of the orbital (s, p, d, f).
The principal quantum number (n) describes the energy level and size. The magnetic quantum number
(ml) describes orbital orientation, and the spin quantum number (ms) describes electron spin.
5. What is the maximum number of electrons that can occupy a single orbital?
A) 1
B) 2
C) 4
D) 8
Correct Answer: 2
Rationale: According to the Pauli Exclusion Principle, a single orbital can hold a maximum of two
electrons, which must have opposite spins. Options A, C, and D violate the Pauli Exclusion Principle
and the capacity of a single orbital.
6. Which of the following electron configurations represents a neutral oxygen atom (Z = 8)?
A) 1s² 2s² 2p⁴
B) 1s² 2s² 2p⁶
C) 1s² 2s² 2p²
1. Which property of light is defined as the distance between two consecutive peaks of a wave?
A) Frequency
B) Amplitude
C) Wavelength
D) Velocity
Correct Answer: Wavelength
Rationale: Wavelength is the distance between consecutive peaks or troughs of a wave. Frequency is
the number of waves passing a point per unit time. Amplitude is the height of the wave, and velocity
is the speed at which the wave travels. Options A, B, and D describe other wave properties.
2. What is the energy of a photon with a frequency of 5.0 × 10^14 Hz? (h = 6.626 × 10^-34 J·s)
A) 3.3 × 10^-19 J
B) 3.3 × 10^-20 J
C) 1.3 × 10^-48 J
D) 5.0 × 10^-14 J
Correct Answer: 3.3 × 10^-19 J
,Rationale: E = hν = (6.626 × 10^-34 J·s)(5.0 × 10^14 Hz) = 3.3 × 10^-19 J. Option B is off by a factor of
10, option C is an incorrect multiplication, and option D uses the frequency directly as energy. Options
B, C, and D are incorrect.
3. According to the Bohr model, what happens when an electron transitions from a higher energy
level to a lower energy level?
A) A photon is absorbed.
B) A photon is emitted.
C) The electron's mass increases.
D) The electron's charge changes.
Correct Answer: A photon is emitted.
Rationale: In the Bohr model, when an electron drops from a higher energy level to a lower one, the
energy difference is released as a photon. Absorption occurs when an electron moves to a higher
level. Mass and charge do not change during electronic transitions. Options A, C, and D are incorrect.
4. Which quantum number describes the shape of an orbital?
A) Principal quantum number (n)
B) Angular momentum quantum number (l)
C) Magnetic quantum number (ml)
D) Spin quantum number (ms)
, Correct Answer: Angular momentum quantum number (l)
Rationale: The angular momentum quantum number (l) determines the shape of the orbital (s, p, d, f).
The principal quantum number (n) describes the energy level and size. The magnetic quantum number
(ml) describes orbital orientation, and the spin quantum number (ms) describes electron spin.
5. What is the maximum number of electrons that can occupy a single orbital?
A) 1
B) 2
C) 4
D) 8
Correct Answer: 2
Rationale: According to the Pauli Exclusion Principle, a single orbital can hold a maximum of two
electrons, which must have opposite spins. Options A, C, and D violate the Pauli Exclusion Principle
and the capacity of a single orbital.
6. Which of the following electron configurations represents a neutral oxygen atom (Z = 8)?
A) 1s² 2s² 2p⁴
B) 1s² 2s² 2p⁶
C) 1s² 2s² 2p²
