JEE Main201815 Apr 2018Evening ShiftChemistryd and f Block ElementsActual
The correct order of spin-only magnetic moments among the following is: (Atomic number: Mn =25, Co =27, Ni =28, Zn =30 )
Options
- A[ ZnCl ₄ ]²⁻> [ NiCl ₄ ]²⁻> [ CoCl ₄ ]²⁻> [ MnCl ₄ ]²⁻
- B[ CoCl ₄ ]²⁻> [ MnCl ₄ ]²⁻> [ NiCl ₄ ]²⁻> [ ZnCl ₄ ]²⁻
- C[ NiCl ₄ ]²⁻> [ CoCl ₄ ]²⁻> [ MnCl ₄ ]²⁻> [ ZnCl ₄ ]²⁻
- D[ MnCl ₄ ]²⁻> [ CoCl ₄ ]²⁻> [ NiCl ₄ ]²⁻> [ ZnCl ₄ ]²⁻
Correct answer
D. [ MnCl ₄ ]²⁻> [ CoCl ₄ ]²⁻> [ NiCl ₄ ]²⁻> [ ZnCl ₄ ]²⁻
Step-by-step solution
The complex having higher number of unpaired electrons will have higher value of spin only magnetic moment. In all these complexes, the central metal ion is in +2 oxidation state. Zn ²⁺ has 3 d¹⁰ outer electronic configuration with 0 unpaired electron. Ni ²⁺ has 3 d^8 outer electronic configuration with 2 unpaired electrons. Co ²⁺ has 3 d^7 outer electronic configuration with 3 unpaired electrons. Mn ²⁺ has 3 d^5 outer electronic configuration with 5 unpaired electrons Hence the correct order of spin-only magnetic