Question

Among the following, the orbital that has the lowest energy is :

• A. $5f$
• B. $4f$
• C. $6s$
• D. $6p$

Answer 1

Answer: (C)

$6s$

According to the $n+l$ rule, the orbital that has the lowest energy is $6s$ with $6+0$ = 6

For 5f = $n+l$ = $5+3$ = 8

For 4f = $n+l$ = $4+3$ = 7

For 6p =$n+l$ = $6+1$ = 7

The $n+l$ values for $5f,4f$ and $6p$ are $8,7$ and $7$ respectively.