QuestionAtomic structure / quantum numbers
Which among the following principal quantum numbers has/have five degenerate d-orbitals?
- (a) 2
- (b) 3 only
- (c) 4 only
- (d) Both 3 and 4
Answer: (d) Both 3 and 4
A d-subshell needs l = 2, which is allowed only when n ≥ 3 (l = 0 to n − 1). n = 2 has only 2s and 2p. Both n = 3 (3d) and n = 4 (4d) have five d-orbitals (m_l = −2 to +2), degenerate in a free atom. → (d)