Answer and Explanation :
Paramagnetic are those which has unpaired electrons and diamagnetic are those in which all electrons are paired.
(a) V³⁺
The electronic configuration is -
![[Ar]3d^1](https://tex.z-dn.net/?f=%5BAr%5D3d%5E1)
The electrons in 3d orbital = 1 (Unpaired)
Thus, the ion is paramagnetic as the electrons are unpaired.
(b) Cd²⁺
The electronic configuration is -
![[Kr]4d^{10}](https://tex.z-dn.net/?f=%5BKr%5D4d%5E%7B10%7D)
The electrons in 4d orbital = 10 (paired)
Thus, the ion is diamagnetic as the electrons are paired.
(c) Co³⁺
The electronic configuration is -
![[Ar]3d^6](https://tex.z-dn.net/?f=%5BAr%5D3d%5E6)
The electrons in 3d orbital = 6 (Unpaired)
Thus, the ion is paramagnetic as the electrons are unpaired.
(d) Ag⁺
The electronic configuration is -
![[Kr]4d^{10}](https://tex.z-dn.net/?f=%5BKr%5D4d%5E%7B10%7D)
The electrons in 4d orbital = 10 (paired)
Thus, the ion is diamagnetic as the electrons are paired.