Which halogen can be oxidised by concentrated nitric acid?

An inorganic white crystalline compound $(A)$ has a rock salt structure. $(A)$ on reaction with conc. $H_2SO_4$ and $MnO_2$ evolves a pungent smelling,greenish-yellow gas $(B)$. Compound $(A)$ gives a white precipitate of $(C)$ with $AgNO_3$ solution. Compounds $(A)$,$(B)$,and $(C)$ will be respectively:

Chlorine is allowed to react with an excess of ammonia. In this reaction, $1$ mole of chlorine can oxidize '$Z$' moles of $NH_3$. The value of '$Z$' is:

Which of the following elements belongs to group $17$ of the periodic table?

Which of the following reactions are correct with respect to the formation of products?
$I$. $2 NaOH + SO_2 \longrightarrow Na_2SO_3 + H_2O$
$II$. $XeF_4 + O_2F_2 \stackrel{143 K}{\longrightarrow} XeF_6 + O_2$
$III$. $PCl_5 + 4 H_2O \longrightarrow H_3PO_4 + 5 HCl$
$IV$. $2 NaNO_2 + 2 HCl \longrightarrow 2 NaCl + NO + NO_2 + H_2O$

Like other halogens,fluorine cannot exhibit higher oxidation states. The reason for this is ...