Match the metal ions given in Column I with the spin magnetic moments of the ions given in Column II and assign the correct code (NEET 2018) Column I Column II A. Co3+ i. 8 B.M. B. Cr3+ ii. 35 B.M. C. Fe3+ iii. 3 B.M. D. Ni2+ iv. 24 B.M. v. 15 B.M. A B C D (a) i ii iii iv (b) iv i ii iii (c) iv v ii i (d) ii iv i ii Ans. (c) Sol. The magnetic moment is calculated as, μ = n(n+2) Where n is the number of unpaired electrons and μ is the magnetic moment. The electronic configuration of 3+ Co Z=27 is 3+ Co 3d It has 4 unpaired electrons. The spin moment is, μ = 4(4+2) = 24 B.M. The electronic configuration of 3+ Cr Z=24 is 3+ Cr 3d It has 3 unpaired electrons. The spin moment is, μ = 3(3+2) = 15 B.M. The electronic configuration of 3+ Fe Z=26 is 3+ Fe 3d It has 5 unpaired electrons. The spin moment is, μ = 5(5+2) = 35 B.M. The electronic configuration of 2+ Ni Z=28 is 2+ Ni 3d It has 2 unpaired electrons. The spin moment is, μ = 2(2+2) = 8 B.M. So, correct answer is A-(iv), B-(v), C-(ii), D-(i). Thus, the correct option is (c).