Match the entries of column I with appropriate entries of column II and choose the correct option out of the four options given.
| Column I (Ion) | Column II (Magnetic moment) |
| (A) Cu2+ | (p) 2.9 BM |
| (B) Fe2+ | (q) 4.0 BM |
| (C) Ni2+ | (r) 1.8 BM |
| (D) Co2+ | (s) 5.0 BM |
Answer & explanation
Correct answer: option 1
The correct answer is option 1. A-r, B-s, C-p, D-q
| Column I (Ion) | Column II (Magnetic moment) |
| (A) Cu2+ | (r) 1.8 BM |
| (B) Fe2+ | (s) 5.0 BM |
| (C) Ni2+ | (p) 2.9 BM |
| (D) Co2+ | (q) 4.0 BM |
(A) Cu2+: [Ar]3d9
No of unpaired electrons = 1
Magnetic moment = \(\sqrt{1(1+2)}\) = \(\sqrt{3}\) ≈ 1.8 BM
(B) Fe2+: [Ar]3d6
No of unpaired electrons = 4
Magnetic moment = \(\sqrt{4(4+2)}\) = \(\sqrt{24}\) ≈ 5.0 BM
(C) Ni2+: [Ar]3d8
No of unpaired electrons = 2
Magnetic moment = \(\sqrt{2(2+2)}\) = \(\sqrt{8}\) ≈ 2.9 BM
(D) Co2+: [Ar]3d7
No of unpaired electrons = 3
Magnetic moment = \(\sqrt{3(3+2)}\) = \(\sqrt{15}\) ≈ 4.0 BM