Question

For $Z{n}^{2+}$, $N{i}^{2+}$, $C{u}^{2+}$ and $C{r}^{2+}$ which of the following statements is correct?

• A. Only $Z{n}^{2+}$ is colourless and $N{i}^{2+}$, $C{u}^{2+}$ and $C{r}^{2+}$ are coloured
• B. All the ions are coloured
• C. All the ions are colourless
• D. $Z{n}^{2+}$ and $C{u}^{2+}$ are colourless while $N{i}^{2+}$ and $C{r}^{2+}$ are coloured

Answer 1

Answer: (A)

$Z{n}^{2+}(3d^{10})$ has zero unpaired electron (colourless).
$N{i}^{2+}(3d^8)$ has $2$ unpaired electrons (coloured).
$C{u}^{2+}(3d^9)$ has $1$ unpaired electron (coloured).
$C{r}^{2+}(3d^4)$ has $4$ unpaired electrons (coloured).