Phenol with Hinsberg's reagent gives

Which of the following phenols has the largest $pK_a$ value (i.e.,is least acidic)?

Which reaction is used to prepare $2$-hydroxybenzaldehyde from phenol?

The major product in the following reaction is:

The order of reactivity of phenol $(I)$,nitrobenzene $(II)$,and benzene $(III)$ towards nitration is:

Which of the following fact$(s)$ explain$(s)$ why $p-$nitrophenol is more acidic than phenol?
$I$. $-I$ Effect of the nitro group.
$II$. Greater resonance effect of the $p-$nitrophenoxy group.
$III$. Steric effect of the bulky nitro group.