Question

Which of the following pairs has both the ions coloured in aqueous solution?
[Atomic numbers of $Sc=21,Ti=22,Ni=28,Cu=29,Mn=25$ ]

• A. $S{c}^{3+},M{n}^{2+}$
• B. $N{i}^{2+},T{i}^{4+}$
• C. $T{i}^{3+},C{u}^{+}$
• D. $M{n}^{2+},T{i}^{3+}$

Answer 1

Answer: (D)

$Sc=21,S{c}^{3+}=[Ar]3d^{0}4s^0=$ no unpaired electrons
$Ti=22,T{i}^{3+}=[Ar]3d^{1}4s^0=1$ unpaired electron
$T{i}^{4+}=[Ar]3d^{\circ }4s^{\circ }$ no unpaired electrons
$Ni=28,N{i}^{2+}=[Ar]3d^{8}4s^2=2$ unpaired electrons
$Cu=29,C{u}^{+}=[Ar]3d^{10}4s^0=$ no unpaired electrons
$Mn=25,M{n}^{2+}=[Ar]3d^{5}4s^2=5$ unpaired electrons