Concentrated $H_2SO_4$ is not used to prepare $HBr$ from $KBr$ because it

Which of the following acids is the weakest?

Which of the following is not a peroxy acid?

Mercury on heating with aqua-regia gives

Which of the following reagents does not oxidize $HCl$?

Choose the $CORRECT$ reason for fluorine being a stronger oxidising agent than chlorine.
$I$. Low enthalpy of dissociation of $F-F$ bond
$II$. High hydration enthalpy of $F^-$
$III$. Low atomisation enthalpy of $F_2$