Chemistry Atomic Structure ETEA 2016
PMDC Verified Question 86 of 95
What are the values of principal quantum number and azimuthal quantum number for the last electron in chlorine atom?
A
\( 1, 6 \)
B
\( 1, 3 \)
C
\( 6, 1 \)
D
\( 3, 1 \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: \( 3, 1 \)
Concept: The quantum numbers \(n\) (principal) and \(l\) (azimuthal) define the specific shell and subshell where the valence electron resides.

Formula: None required.

Solution:
  • Chlorine has an atomic number \( Z = 17 \).
  • Its electronic configuration is \( 1s^2, 2s^2, 2p^6, 3s^2, 3p^5 \).
  • The last (valence) electron enters the \( 3p \) orbital.
  • For a \( 3p \) orbital, the principal quantum number \( n = 3 \).
  • The azimuthal quantum number for a \( p \)-orbital is \( l = 1 \).
  • Therefore, \( (n, l) = (3, 1) \).


Why other options are incorrect: They do not match the quantum numbers of the \( 3p \) subshell.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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