Identify the strongest oxoacid of halogen from the following.

Which of the following aqueous acids is the most acidic?

When $MnO_2$ and $H_2SO_4$ are added to $NaCl$,the greenish-yellow gas liberated is:

$AgNO_3$ is generally kept in colored bottles because it .......

Artificial smoke screens are made by

Which of the following are not in accordance with the property mentioned against them?
$I$. $F_2 > Cl_2 > Br_2 > I_2$ : Oxidising power
$II$. $MI > MBr > MCl > MF$ : Ionic character of metal halide
$III$. $F_2 > Cl_2 > Br_2 > I_2$ : Bond dissociation enthalpy
$IV$. $HI < HBr < HCl < HF$ : Hydrogen-halogen bond strength