$P_4O_{10}$ is not used to dry $NH_3$ gas because

Among the given oxides of nitrogen; $N_2O$,$N_2O_3$,$N_2O_4$ and $N_2O_5$,the number of compound/$(s)$ having $N-N$ bond is ...

The compound$(s)$ which generate$(s)$ $N_2$ gas upon thermal decomposition below $300^{\circ} C$ is (are)
$(A)$ $NH_4 NO_3$
$(B)$ $(NH_4)_2 Cr_2 O_7$
$(C)$ $Ba(N_3)_2$
$(D)$ $Mg_3 N_2$

Account for the following observations:
$(A)$ $AlCl_3$ is a Lewis acid.
$(B)$ Though fluorine is more electronegative than chlorine yet $BF_3$ is a weaker Lewis acid than $BCl_3$.
$(C)$ $PbO_2$ is a stronger oxidizing agent than $SnO_2$.
$(D)$ The $+1$ oxidation state of thallium is more stable than its $+3$ state.

Which of the following reactions give phosphine $(PH_3)$?
$(i)$ Reaction of calcium phosphide with water
$(ii)$ Heating white phosphorus with concentrated $NaOH$ solution in an inert atmosphere
$(iii)$ Heating red phosphorus with alkali

In which of the following is the $P - O - P$ bond present?