CHEM134 C003 LESSON 3 QUIZ:
ELECTRONIC STRUCTURE AND
PERIODIC PROPERTIES QUESTIONS
AND ANSWERS WITH VERIFIED
SOLUTIONS 2026/2027 UPDATE. JUST
RELEASED
1. Calculate the energy of a single photon of light with a wavelength of 450 nm.
A. 6.63 x 10^-34 J
B. 2.99 x 10^-19 J
C. 4.42 x 10^-19 J
D. 4.42 x 10^-17 J
Answer: C
Conceptual Explanation: Using E = hc/λ, where h = 6.626e-34 J·s, c = 3.00e8 m/s, and λ =
450e-9 m, the calculation yields approximately 4.42e-19 J.
,2. Which of the following transitions in a hydrogen atom would result in the emission of a
photon with the highest frequency?
A. n=3 to n=2
B. n=5 to n=2
C. n=6 to n=3
D. n=2 to n=1
Answer: D
Conceptual Explanation: Frequency is proportional to the energy difference. The energy
gap between n=2 and n=1 is significantly larger than transitions between higher levels.
3. What is the de Broglie wavelength of an electron (mass = 9.11 x 10^-31 kg) moving at 1.0%
the speed of light?
A. 6.63 x 10^-10 m
B. 7.27 x 10^-11 m
C. 2.42 x 10^-12 m
D. 2.42 x 10^-10 m
Answer: D
Conceptual Explanation: Using λ = h/mv, where v = 0.01 * 3.00e8 m/s, λ = 6.626e-34 /
(9.11e-31 * 3.00e6) = 2.42e-10 m.
, 4. According to the Heisenberg Uncertainty Principle, if the uncertainty in the position of an
electron is reduced, what happens to the uncertainty in its momentum?
A. It increases
B. It decreases proportionally
C. It remains constant
D. It becomes zero
Answer: A
Conceptual Explanation: The principle states ΔxΔp ≥ h/4π. Decreasing Δx (position
uncertainty) necessitates an increase in Δp (momentum uncertainty).
5. How many radial nodes are present in a 4p orbital?
A. 0
B. 1
C. 2
D. 3
Answer: C
Conceptual Explanation: Radial nodes = n - l - 1. For 4p, n=4 and l=1, so 4 - 1 - 1 = 2.
6. Which set of quantum numbers (n, l, ml, ms) is not permissible?
A. 3, 2, -2, +1/2
ELECTRONIC STRUCTURE AND
PERIODIC PROPERTIES QUESTIONS
AND ANSWERS WITH VERIFIED
SOLUTIONS 2026/2027 UPDATE. JUST
RELEASED
1. Calculate the energy of a single photon of light with a wavelength of 450 nm.
A. 6.63 x 10^-34 J
B. 2.99 x 10^-19 J
C. 4.42 x 10^-19 J
D. 4.42 x 10^-17 J
Answer: C
Conceptual Explanation: Using E = hc/λ, where h = 6.626e-34 J·s, c = 3.00e8 m/s, and λ =
450e-9 m, the calculation yields approximately 4.42e-19 J.
,2. Which of the following transitions in a hydrogen atom would result in the emission of a
photon with the highest frequency?
A. n=3 to n=2
B. n=5 to n=2
C. n=6 to n=3
D. n=2 to n=1
Answer: D
Conceptual Explanation: Frequency is proportional to the energy difference. The energy
gap between n=2 and n=1 is significantly larger than transitions between higher levels.
3. What is the de Broglie wavelength of an electron (mass = 9.11 x 10^-31 kg) moving at 1.0%
the speed of light?
A. 6.63 x 10^-10 m
B. 7.27 x 10^-11 m
C. 2.42 x 10^-12 m
D. 2.42 x 10^-10 m
Answer: D
Conceptual Explanation: Using λ = h/mv, where v = 0.01 * 3.00e8 m/s, λ = 6.626e-34 /
(9.11e-31 * 3.00e6) = 2.42e-10 m.
, 4. According to the Heisenberg Uncertainty Principle, if the uncertainty in the position of an
electron is reduced, what happens to the uncertainty in its momentum?
A. It increases
B. It decreases proportionally
C. It remains constant
D. It becomes zero
Answer: A
Conceptual Explanation: The principle states ΔxΔp ≥ h/4π. Decreasing Δx (position
uncertainty) necessitates an increase in Δp (momentum uncertainty).
5. How many radial nodes are present in a 4p orbital?
A. 0
B. 1
C. 2
D. 3
Answer: C
Conceptual Explanation: Radial nodes = n - l - 1. For 4p, n=4 and l=1, so 4 - 1 - 1 = 2.
6. Which set of quantum numbers (n, l, ml, ms) is not permissible?
A. 3, 2, -2, +1/2
