In which one of the pairs of ion given, there is an ion that forms a co-ordination compound with both aqueous sodium hydroxide and ammonia and an other ion that forms a co-ordination compound only with aqueous sodium hydroxide?

Options

A. `Pb^(2+), Cu^(2+)`
B. `Zn^(2+), Al^(3+)`
C. `Cu^(2+), Zn^(2+)`
D. `Al^(3), Cu^(2+)`

Answer

B

Explanation

`Zn^(2+)` ion reacts with aq. NaOH and `NH_(3)` and forms a coordination compound.
`Zn^(2+)+4NaOH rarr [Zn(OH)_(4)]^(2-)+4Na^(+)`
`Zn^(2+)+4NH_(3) rarr [Zn(NH_(3))_(4)]^(2+)`
But, `Al^(3+)` ion reacts only with NaOH.
`Al^(3)+4NaOH rarr [Al(OH)_(4)]^(-)+4Na^(+)`