Question

A piece of magnesium ribbon was heated to redness in an atmosphere of nitrogen and then cooled with water. The gas evolved is

• A. Ammonia
• B. Hydrogen
• C. Nitrogen
• D. Oxygen

Answer 1

The correct option is A Ammonia

Li and Mg has diagonal relationship with each other due to their similar size. Hence they have some chemical properties in common. One such property is the reaction with $N_2$.
Li and Mg react with $N_2$ to form nitrides.

$3Mg+N_2\to M{g}_3{N}_2$
$N_2$ molecule is very stable so it requires a lot of energy to convert $N_2$ into $N^{3-}$. This energy comes from the lattice energy evolved when the crystalline solid is formed.
These crystalline solids on reacting with water liberates $N{H}_3$ and form metal hydroxide.
$M{g}_3{N}_2+6H_{2}O\to 3Mg(OH{)}_2+2N{H}_3$