$NaOH$ is prepared by the method:

$NaOH$ (solid) $+ CO \xrightarrow{200^\circ C} X$; product $X$ is

Sodium metal on dissolution in liquid ammonia gives a deep blue solution due to the formation of:

$A$ metal $M$ reacts with nitrogen gas to afford $M_3N$. $M_3N$ on heating at high temperature gives back $M$ and on reaction with water produces a gas $B$. Gas $B$ reacts with aqueous solution of $CuSO_4$ to form a deep blue compound. $M$ and $B$ respectively are

Which of the following has the lowest melting point?

Which of the following statements about $Na_2O_2$ is not correct?