$PCl_5$ exists but $NCl_5$ does not because:

The oxide which forms a dimer is

Small quantities of $NO$ and $HNO_3$ are formed as impurities when $N_2$ is prepared from $NH_4Cl_{(aq)}$ and $NaNO_{2(aq)}$. These impurities can be removed by passing the $N_2$ gas through which of the following?

In $P_4O_6$,the number of oxygen atoms attached to each phosphorus atom is .......

How is ammonia manufactured industrially?

Write a note on $p$-block elements of the periodic table.