COMEDK2024Chemistryd and f Block ElementsActual
The metallic ions that have almost same spin only magnetic moment are : (i) Co ²⁺ (ii) Mn ²⁺ (iii) Cr ²⁺ (iv) Cr ³⁺
Options
- A(i) and (iv)
- B(i) and (iii)
- C(i) and (ii)
- D(iii) and (iv)
Correct answer
A. (i) and (iv)
Step-by-step solution
The spin-only magnetic moment is calculated using the formula = n(n+2) B.M., where n is the number of unpaired electrons. For Co ²⁺ ( Z=27 ): The electronic configuration is [Ar] 3d^7 . The number of unpaired electrons n = 3 . Thus, = 3(3+2) = 15 3.87 B.M. For Mn ²⁺ ( Z=25 ): The electronic configuration is [Ar] 3d^5 . The number of unpaired electrons n = 5 . Thus, = 5(5+2) = 35 5.92 B.M. For Cr ²⁺ ( Z=24 ): The electronic configuration is [Ar] 3d^4 . The number of unpaired electrons n = 4 . Thus, = 4(4+2) = 24 4.9