Official Correct Choice:
Option A: \( 4p, 5s, 4d, 5p, 6s, 4f, 5d \)
Concept: The Aufbau principle states that orbitals are filled in order of their increasing \( (n+l) \) values.
Formula: $$ \text{Energy} \propto (n+l) $$
Solution: - Let's verify the \( (n+l) \) values for the correct sequence (Option A):
- \( 4p \): \( 4+1=5 \)
- \( 5s \): \( 5+0=5 \) (Higher \( n \) than \( 4p \), so it comes after)
- \( 4d \): \( 4+2=6 \)
- \( 5p \): \( 5+1=6 \) (Higher \( n \) than \( 4d \), so it comes after)
- \( 6s \): \( 6+0=6 \) (Higher \( n \) than \( 5p \), so it comes after)
- \( 4f \): \( 4+3=7 \)
- \( 5d \): \( 5+2=7 \) (Higher \( n \) than \( 4f \), so it comes after)
- The sequence strictly adheres to the \( (n+l) \) hierarchy.
Why other options are incorrect: They jumble the sequence, placing higher energy subshells before lower ones (e.g., jumping from \( 4p \) back down to \( 4s \) or \( 3s \)).
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