Nitrogen forms only $NCl_3$,whereas phosphorus forms both $PCl_3$ and $PCl_5$. Why?

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?

Given below are two statements:
Statement $I$: Like nitrogen that can form ammonia,arsenic can form arsine.
Statement $II$: Antimony cannot form antimony pentoxide.
In the light of the above statements,choose the most appropriate answer from the options given below:

Why is $N_2$ less reactive at room temperature?

$A$ $p$-block element $(E)$ and hydrogen form a binary cation $(EH_{x}^{+})$,while $EH_{3}$ on treatment with $K_{2}HgI_{4}$ in alkaline medium gives a precipitate of basic mercury$(II)$amido-iodine. Given below are first ionisation enthalpy values $(kJ \ mol^{-1})$ for the first element of each group $13, 14, 15$,and $16$. Identify the correct first ionisation enthalpy value for element $E$.

What compounds are formed when phosphine $(PH_3)$ is absorbed in a solution of mercuric chloride $(HgCl_2)$?