Which one of the following compounds on strong heating evolves ammonia gas?

With reference to protonic acids,which of the following statements is correct regarding the basicity of $PH_3$ and $NH_3$?

Which of the following tendencies remains unchanged on going down in the nitrogen family (Group-$15$)?

$Cu +$ conc. $HNO_3$ (hot) $\rightarrow Cu(NO_3)_2 + X$ (oxide of nitrogen);
then $X$ is

Phosphorus forms a number of oxoacids. Out of these oxoacids,phosphinic acid $(H_3PO_2)$ has strong reducing properties. Write its structure and also write a reaction showing its reducing behavior.

In the following reaction,assign the correct option for the underlined atom in the product of complete hydrolysis at $R.T.$:
$\underline{N}_2O_3 + H_2O \longrightarrow 2HNO_2$