Question

The stability of complexes of $C{u}^{2+},N{i}^{2+},C{o}^{2+}$ and $F{e}^{2+}$ varies in the order

• A. $C{u}^{2+}>N{i}^{2+}>C{o}^{2+}>F{e}^{2+}$
• B. $C{u}^{2+}>F{e}^{2+}>N{i}^{2+}>C{o}^{2+}$
• C. $N{i}^{2+}>C{o}^{2+}>F{e}^{2+}>C{u}^{2+}$
• D. $C{u}^{2+}<N{i}^{2+}<C{o}^{2+}<F{e}^{2+}$

Answer 1

Answer: (D)

Smaller cations form more stable complexes. Ionic radii : $C{u}^{2+}>N{i}^{2+}>C{o}^{2+}>F{e}^{2+}$
$\therefore$ Stability : $C{u}^{2+}>N{i}^{2+}>C{o}^{2+}>F{e}^{2+}$