Question

Which of these ions is expected to be coloured in aqueous solution?
$I.F{e}^{3+}$
$II.N{i}^{2+}$
$III.A{l}^{3+}$

• A. $I$ and $II$
• B. $II$ and $III$
• C. $I$ and $III$
• D. $I,II$ and $III$

Answer 1

Answer: (A)

$4$ unpaired electrons,
$\therefore$ Coloured ion

$2$ unpaired electrons,
$\therefore$ Coloured ion
$III.A{l}^{3+}=[Ne]$
No unpaired electron in $3d$, thus colourless ion.