Which of the following elements forms $p\pi-p\pi$ bond with itself?

Assertion : Molecular nitrogen is less reactive than molecular oxygen.
Reason : The bond length of $N_2$ is shorter than that of oxygen.

Which method is used to produce nitric acid?

Which is the correct sequence in the following properties? For the correct order mark $(T)$ and for the incorrect order mark $(F)$.
$(a)$ Lewis acidity order : $SiF_4 < SiCl_4 < SiBr_4 < SiI_4$
$(b)$ Melting point : $NH_3 > SbH_3 > AsH_3 > PH_3$
$(c)$ Boiling point : $NH_3 > SbH_3 > AsH_3 > PH_3$
$(d)$ Dipole moment order : $NH_3 > SbH_3 > AsH_3 > PH_3$

The reaction of zinc with dilute and concentrated nitric acid,respectively,produces:

$P_4O_{10}$ cannot be used to dry $NH_3$ because ..............