Question

Which of the following group contains coloured ions?
1. $C{u}^{+}$
2. $T{i}^{4+}$
3. $C{o}^{2+}$
4. $F{e}^{2+}$

• A. $1,4$
• B. $3,4$
• C. $2,3$
• D. $1,2$

Answer 1

The correct option is B $3,4$

$C{u}^{+}$ and $T{i}^{+4}$ have fully filled and empty d orbital respectively. Hence due to absence of unpaired electrons,they will be colourless. But $F{e}^{+2}$ and $C{o}^{+2}$chave unpaired electrons. Hence they will be coloured.