Q. Which of the following has the maximum number of unpaired $d$-elelments?
A) $Fe^{2 +}$
B) ${Cu}^{+}\$
C) $Zn$
D) $Ni^{3 +}$
Explanation
(a)
$Fe^{2 +} = \lbrack Ar\rbrack\ 3d^{6}4s^{0} \Rightarrow 4$ unpaired electrons
$Cu^{+} = \lbrack Ar\rbrack\ 3d^{10}4s^{0} \Rightarrow 0$ unpaired electrons
$Zn = \lbrack Ar\rbrack\ 3d^{10}4s^{2} \Rightarrow 0$ unpaired electrons
$Ni^{3 +} = \lbrack Ar\rbrack\ 3d^{7}4s^{0} \Rightarrow 3$ unpaired electrons
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.