Question

How many orbitals in this subshell have an unpaired electron, if an atom has eight electrons in a $3d$ subshell?

• A. $1$
• B. $2$
• C. $3$
• D. $4$
• E. $5$

Answer 1

The correct option is B $2$

The $3d$-subshell will contain a total of five $3d$-orbitals. When assigning electrons in orbitals, each electron will first fill all the orbitals with similar energy (also referred to as degenerate) before pairing with another electron in a half-filled orbital. The atom having eight electrons should have two $3d$ orbitals with an unpaired electron.

Hence, the correct option is $\text{B}$