Question

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

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

Answer 1

The correct option is A Only $Z{n}^{2+}$ is colourless and $N{i}^{2+},C{u}^{2+}\text{and}C{r}^{2+}$ are coloured

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