JEE MainChemistryd and f Block Elements
The spin-only magnetic moment of a transition metal ion is 3.87 BM . The ion is :
Options
- ACo ²⁺
- BNi ²⁺
- CFe ²⁺
- DTi ²⁺
Correct answer
A. Co ²⁺
Step-by-step solution
The spin-only magnetic moment is given by = n(n+2) BM , where n is the number of unpaired electrons. Given = 3.87 BM , which corresponds to 15 BM . Thus, n(n+2) = 15 n = 3 . Let us check the number of unpaired electrons in the given ions: Co ²⁺ : [ Ar ] 3d⁷ (has 3 unpaired electrons) Ni ²⁺ : [ Ar ] 3d⁸ (has 2 unpaired electrons) Fe ²⁺ : [ Ar ] 3d⁶ (has 4 unpaired electrons) Ti ²⁺ : [ Ar ] 3d² (has 2 unpaired electrons) Therefore, Co ²⁺ has exactly 3 unpaired electrons and a magnetic moment of 3.87 BM . Answer: Co ²