Question

For $Z{n}^{2+}$, $N{i}^{2+}$, $Cu$, 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 $Cr$ 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

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

Since $Z{n}^{+2}$ have fully filled $d$ orbital having no unpaired electrons,it does not undergo electronic transitions,hence colourless.However,rest of the elements given as $N{i}^{+2}$ , $C{u}^{+2}$ and $C{r}^{+2}$ has unpaired electrons which can undergo electronic transitions and hence show colours.