Number of paramagnetic ions among the following d- and f-block metal ions is . Mn2+, Cu2+, Zn2+, Yb2+, Sc3+, La3+, Gd3+, Lu3+, Ti4+, Ce4+ (Atomic number of Mn = 25, Cu = 29, Zn = 30, Yb = 70, Sc = 21, La = 57, Gd = 64, Lu = 71, Ti = 22, Ce = 58)
Answer
3
Solution
Mn2+: [Ar]3d5 – 5 unpaired ✓
Cu2+: [Ar]3d9 – 1 unpaired ✓
Zn2+: [Ar]3d10; Yb2+: [Xe]4f14; Lu3+: [Xe]4f14 – all paired
Sc3+, Ti4+: [Ar]; La3+, Ce4+: [Xe] – no unpaired electron
Gd3+: [Xe]4f7 – 7 unpaired ✓
∴ Paramagnetic ions = 3 ( Mn2+, Cu2+, Gd3+)
Answer: 3