Which of the following oxides is highly basic?

Match the following:

Metals	Minerals
$1$. Lithium	$c$. Lepidolite
$2$. Barium	$a$. Witherite
$3$. Magnesium	$d$. Carnallite
$4$. Strontium	$b$. Celestine

Which one of the following is an $s$-block element?

Sodium nitrate $(NaNO_3)$ decomposes above $800\ ^oC$ to give:

Which of the following does not liberate a brown gas?

$A$ metal $M$ reacts with $N_2$ to form a compound $A$ $(M_3N)$. Heating $A$ at a high temperature gives back $M$,and passing $A$ through $H_2O$ results in the evolution of gas $B$. Gas $B$ turns $CuSO_4$ solution blue. What are $A$ and $B$ respectively?