Question

Which of the following group contains coloured ions?
1. $Cu ^{+}$
2. $Ti ^{+4}$
3. $Co ^{2+}$
4. $Fe ^{2+}$

• A. 1, 4
• B. 3,4
• C. 2,3
• D. 1,2

Answer 1

Answer: (B)

$Cu ^{+}$and $Ti ^{+4}$ have fully filled and empty $d$ orbital respectively. Hence due to absence of unpaired electrons, they will be colourless. But $Fe ^{+2}$ and $Co ^{+2}$ chave unpaired electrons. Hence they will be coloured.