Question

A metal $X$ on heating in nitrogen gas gives a compound $Y$. Compound $Y$ on treatment with $H_{2}O$ gives a colourless gas which when passed through $CuS{O}_4$ solution gives a blue colour. Then, compound $Y$ is:

• A. $Mg(N{O}_3{)}_2$
• B. $M{g}_3{N}_2$
• C. $N{H}_3$
• D. $MgO$

Answer 1

Answer: (B)

$M{g}_3{N}_2$

When magnesium metal is heated in nitrogen, it forms magnesium nitride.

$3Mg+N_2\to M{g}_3{N}_2$

Hydrolysis of magnesium nitride gives magnesium hydroxide and ammonia.

$M{g}_3{N}_2\stackrel{water}{\to }Mg(OH{)}_2+N{H}_3\uparrow$

When ammonia gas is dissolved in the copper sulphate solution, blue colour is obtained.