Identify the alkali metal having the smallest atomic size from the following.

When an alkali metal dissolves in liquid ammonia,the solution can acquire different colours. Explain the reasons for this type of colour change.

Give the preparation,properties,and uses of sodium chloride ($NaCl$ $-$ Rock salt).

Which of the following $s$-block elements forms a nitride directly by reacting with $N_2$?

$NaOH$ is prepared by which of the following methods?

Compound $A$ is prepared by the electrolysis of an aqueous solution of $B$ using a Castner-Kellner cell with mercury as the cathode and carbon as the anode. $A$ and $B$ respectively are: