The dand fblock elements - Result Question 5
####5. The number of $d$-electrons in $Fe^{2+}(Z=26)$ is not equal to the number of electrons in which one of the following?
[2015]
(a) p-electrons in $Cl(Z=17)$
(b) $d$-electrons in $Fe(Z=26)$
(c) $p$-electrons in $Ne(Z=10)$
(d) $s$-electrons in $Mg(Z=12)$
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Solution:
- (a) $Fe^{+2}=3 d^{6}$ (number of ’ $d$ ’ electrons =6)
In $Cl=1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{5}$
total $p$ electrons $=11$, which are not equal to number of ’ $d$ ’ electrons in $Fe^{+2}$
$p$-electrons in $Ne=1 s^{2} 2 s^{2} 2 p^{6}=6$
$s$-electrons in $Mg=1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2}=6$
