The number of `d` electrons in `Fe^(2+)` (atomic number of `Fe = 26`) is not equal to that of the.

Options

A. p-electrons in Ne (At. No. =10)
B. s-electrons in Mg (At. No. =12)
C. d-electrons in Fe
D. p-electrons in `Cl^-` (At. No. Of Cl =17)

Answer

D

Explanation

`._26Fe=[Ar]3d^6, 4s^2 rArr ` No. of d electron =6
`Fe^(2+)=[Ar]3d^6 , 4s^0 rArr` No. of d electron =6
`._10Ne=1s^2 2s^2 2p^6 rArr ` No. of p electron =6
`._12Mg=1s^2 2s^2 2p^6 3s^2 rArr` No. of s electron = 6
`Cl^(-)=1s^2 2s^2 2p^6 3s^2 3p^6 rArr` No. of p electron =12
Hence the ans. is `Cl^-`