Which reaction can not be used for the preparation of halogen acid

$\left(A\right)<mspace\; width="1em"></mspace>2KBr<mspace\; width="1em"></mspace>+H_{2}S{O}_4(conc.)<mspace\; width="1em"></mspace>\to K_{2}S{O}_4<mspace\; width="1em"></mspace>+2HBr$
$\left(B\right)<mspace\; width="1em"></mspace>NaCl<mspace\; width="1em"></mspace>+H_{2}S{O}_4(conc.)<mspace\; width="1em"></mspace>\to NaHS{O}_4<mspace\; width="1em"></mspace>+HCl$
$\left(C\right)<mspace\; width="1em"></mspace>NaHS{O}_4<mspace\; width="1em"></mspace>+NaCl<mspace\; width="1em"></mspace>\to N{a}_{2}S{O}_4<mspace\; width="1em"></mspace>+HCl$
$\left(D\right)<mspace\; width="1em"></mspace>Ca{F}_2<mspace\; width="1em"></mspace>+H_{2}S{O}_4(conc.)<mspace\; width="1em"></mspace>\to CaS{O}_4<mspace\; width="1em"></mspace>+2HF$

The most volatile halogen acid is

1. HF

2. HCl

3. HBr

4. HI

Which of the following pairs of molecules have the almost identical bond dissociation energy?

1. F₂ and H₂

2. N₂ and CO

3. F₂ and I₂

4. HF and O₂

${\mathrm{l}}_2$ reacts with aqueous ${\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3$ to give ${\mathrm{Na}}_2{\mathrm{S}}_4{\mathrm{O}}_6$ and Nal. The products of the reaction of Cl₂ with aqueous ${\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3$ are:

1.  ${\mathrm{Na}}_2{\mathrm{S}}_4{\mathrm{O}}_6$ + NaCl

2.  ${\mathrm{NaHSO}}_4$ + HCl

3.  ${\mathrm{NaHSO}}_3$ + HCl

4.  ${\mathrm{NaHSO}}_3$ + NaCl