Concept: The electron capacity of an entire subshell is dictated by its azimuthal quantum number (\( l \)).
Formula: $$ \text{Max Electrons} = 2(2l + 1) $$
Solution: - Note on exact phrasing: The question asks about a "\( 4d \) orbital" but the correct answer treats it as a "\( 4d \) subshell". In strict quantum terms, a single spatial orbital holds 2 electrons. A subshell holds more. However, in standard high school testing, "orbital" is frequently used interchangeably with "subshell".
- For a \( d \)-subshell, \( l = 2 \).
- Number of degenerate orbitals = \( 2(2) + 1 = 5 \).
- Since each orbital holds 2 electrons, the entire \( d \)-subshell holds a maximum of \( 5 \times 2 = 10 \) electrons.
Why other options are incorrect: A \( 4d \) orbital has a different shape (clover/double-dumbbell) than a \( 4p \) orbital (dumbbell). Zinc (\( Z=30 \)) only fills up to \( 3d^{10} \); its \( 4d \) is completely empty. The \( 4f \) orbital has a higher energy than \( 4d \) within the principal quantum number 4.
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.