What is $Z$ in the above sequence of reactions?

The acidic property of phenol is due to which of the following?

The product$(s)$ of the reaction is/are:

Phenol,when it first reacts with concentrated sulphuric acid and then with concentrated nitric acid,gives:

The product of the following reaction is $P$.
$4-hydroxybenzaldehyde + PhMgBr (1 \text{ equiv.}) \xrightarrow{aq. NH_4Cl} P$
The number of hydroxyl groups present in the product $P$ is . . . . . . .

Which of the following conversions represents the Fries rearrangement?