Question

(a) Which metal in the first transition series (3d series) exhibits $+1$ oxidation state most frequently and why?
(b) Which of the following cations are coloured in aqueous solutions and why?
$S{c}^{3+},V^{3+},T{i}^{4+},M{n}^{2+}$
(At. Nos. $Sc=21,V=23,Ti=22,Mn=25$)

Answer 1

$\left(a\right)$ $Cu$ exhibits $+1$ oxidation state most frequently as it electronic configuration is $\left[Ar\right]3d^{10}4s^1$ and of $C{u}^{+}$ is $\left[Ar\right]3d^{10}$ which is stable pseudo-inert gas configuration that is why it shows $+1$ oxidation state.

$\left(b\right)$ These ions which have unpaired electrons shows colour in aqueous solution:

$S{c}^{+3}=0$ unpaired electron

$V^{3+}=2$ unpaired electron

$T{i}^{+4}=0$ unpaired electron

$M{n}^{+2}=2$ unpaired electron