Question

The number of d-electrons in $F{e}^{2+}$(Z $=26$) is not equal to the number of electrons in which one of the following?

• A. d - electrons in Fe (Z $=26$)
• B. p - electrons in Ne (Z $=10$)
• C. s - electrons in Mg (Z $=12$)
• D. p - electrons in Cl (Z $=17$)

Answer 1

The correct option is D p - electrons in Cl (Z $=17$)

Electronic configuration of the elements are:

$F{e}^{2+}:1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^6$

number of d-electrons=6

$F{e}^{2+}:1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^6$-has 6 electrons in d-orbital i.e. same as in d- robital of$F{e}^{2+}$

$Ne:1s^{2}2s^{2}2p^6$-has 6 electrons in p-orbital i.e. same as in d- robital of $F{e}^{2+}$

$Mg:1s^{2}2s^{2}2p^{6}3s^2$-has (2+2+2) 6 electrons in s-orbital i.e. same as in d- robital of $F{e}^{2+}$

$Cl:1s^{2}2s^{2}2p^{6}3s^{2}3p^5$-has (6+5) 11 electrons in p-orbital and are not same as in d- robital of $F{e}^{2+}$.