Question

A metal x on heating in nitrogen gas gives y. y on treatment with h2o gives a colourless gas which when passed through cuso4 solution gives blue colour. y is (a) mg(no3 ) 2 (b) mg2n3 (c) mgcl2 (d) mgo

Answer 1

Y is Mg2N3

Magnesium reacts with nitrogen to form magnesium nitride

Magnesium nitride reacts with water to form ammonia and magnesium hydroxide

When ammonia gas is passed through CuSO4 solution, it forms a blue precipitate.

Answer 2

Answer : The correct option is, (b) $Mg_3N_2$

Explanation :

When a metal magnesium (Mg) on heating in nitrogen gas gives magnesium nitride $(Mg_3N_2)$. Magnesium nitride on treatment with water gives magnesium hydroxide and ammonia gas which is a colorless gas which when passed through copper sulfate solution gives tetraamminecopper(II)sulfate complex which is blue in color.

The reactions involved are :

$Mg(s)+N_2(g)\overset{\Delta}\rightarrow Mg_3N_2(s)$

$Mg_3N_2(s)+H_2O(l)\rightarrow Mg(OH)_2(s)+NH_3(g)$

$NH_3(g)+CuSO_4(aq)\rightarrow [Cu(NH_3)_4]SO_4$

In this,

x = magnesium element (Mg)

y = magnesium nitride $(Mg_3N_2)$

Hence, the correct option is, (b) $Mg_3N_2$