Which of the following compounds is coloured

Options

A. `TiCl_3`
B. `FeCl_3`
C. `CoCl_2`
D. All of these

Answer

D

Explanation

The compounds having metal ions with unpaired electrons, are coloured. Thus,
in `TiCl_3`
`Ti^(3+) = [Ar] 3d^1` (one unpaired electron)
in `FeCl_3`
`Fe^(3+) = [Ar] 3d^5` (Five unpaired electrons)
in `CoCl_2`
`Co^(2+) = [Ar] 3d^7` (Three unpaired electrons)
Hence, all compounds are coloured.