(i) Which one of the following is more paramagnetic `Fe^(2+) or Fe^(3+)?` Explain.
(ii) What is the number of unpaired electrons in `Mn^(2+)` ion? (At.no. Mn= 25).

Explanation

(i) Electronic configuration
`Fe=[Ar] 4s^(2) 3d^(6)`

`Fe^(2+) ` has 4 unpaired electrons while `Fe^(3+)` has 5 unpaired electrons `Fe3^+` is more paramagnetic than `Fe2^+.`
Magnetic moment is directly proportional to number of unpaired elections.
(ii) The electronic configuration of Mn (Z= 25) is
Mn (Z=25) `=1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^5, 4s^2,`
For `Mn^(2+) (Z=23) =1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^5`
Mn `=[Ar] 4s^2 3d^5`
`Mn^(2+)=[Ar] (##OSW_ISC_SQP_CHE_XI_QP_01_E01_023_S02.png" width="80%">
Thus the number of unpaired electrons in `Mn^(2+)` is ion is 5.