A metal `M` reacts with `N_(2)` to give a compound `'A'(M_(3)N)`. 'A' on heating at high temperature gives back `'M'` and `'A'` on reacting with `H_(2)O` gives a gas 'B'.'B' turns `CuSO_(4)` solution blue on passing through it `A` and `B` can be

Options

A. Al and `NH_(3)`
B. Li and `NH_(3)`
C. Na and `NH_(3)`
D. Mg and `NH_(3)`

Answer

B

Explanation

Lithium form nitride on heating with nitrogen. Lithium nitride gives ammonia when heated with `H_(2)O`. Ammonia gas form tetrammine copper complex with `CuSO_(4)` solution.
`6Li +N_(2) to 2Li_(3)N`
`Li_(3)N +3H_(2)O to 3LiOH +NH_(3)`
`CuSO_(4) +4NH_(3) to [Cu(NH_(3))_(4) ] SO_(4)`