Which of the following processes cannot produce $Cl_2$ gas?

$HI$ cannot be prepared by the reaction of concentrated $H_2SO_4$ with $KI$ because:

Chlorine reacts with hot and concentrated $NaOH$ and produces compounds $(X)$ and $(Y)$. Compound $(X)$ gives a white precipitate with silver nitrate solution. The average bond order between $Cl$ and $O$ atoms in $(Y)$ is

Select the incorrect statement from the following.

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

Bleaching action of chlorine is due to