Which of the following is not hygroscopic?

$H_2$ gas is not produced in which of the following reactions?

$A$ metal $M$ reacts with $N_2$ to give a compound '$A$' $(M_3N)$. '$A$' on heating at high temperature gives back '$M$' and '$A$' on reacting with $H_2O$ gives a gas '$B$'. '$B$' turns $CuSO_4$ solution blue on passing through it. $A$ and $B$ can be

Which of the following are the by-products in the Solvay process for the manufacture of $Na_2CO_3$?

$STATEMENT-1$: Alkali metals dissolve in liquid ammonia to give a blue solution because
$STATEMENT-2$: Alkali metals in liquid ammonia give solvated species of the type $[M(NH_3)_n]^{+}$ ($M=$ alkali metals).

On heating,$LiNO_3$ gives how many compounds among the following?
$Li_2O, N_2, O_2, LiNO_2, NO_2$