Question

A '$d$' subshell containing four unpaired electrons can exchange:

• A. Four times
• B. Three times
• C. Sixteen times
• D. Six times

Answer 1

The correct option is D Six times

Number of unpaired electrons given = 4

According to Pauli's exclusion principle, one orbital can accommodate only two electrons.

Thus a '$d$' subshell containing four unpaired electrons can exchange ${}^4{C}_2$ times.
${}^4{C}_2$ = $\frac{4!}{2!2!}$ = 6.