Which of the following ions will exhibit colour in aqueous solution ?

Options

A. `La^(3+)(Z=57)`
B. `Ti^(3+)(Z=22)`
C. `Lu^(3+)(Z=71)`
D. `Sc^(3+)(Z=21)`

Answer

B

Explanation

`Ti^(3+)(Z=22)`
Ions which have unpaired electrons exhibit colour in solution. `Ti^(3+)` has an outer electronic configuration of `4s^(0)`, `3d^(1)`, i.e, 1 unpaired electron. Thus its solution will be coloured.
`Sc^(3+) to d^(0)`
In case of `La^(3+)`, `4f^(0)` configuration is present and in `Lu^(3+)`, `4f^(14)` is present. So, there is no possibility of `f-f` transition, hence these ions do not appear coloured.