Phenol is used as a/an.......?

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

The reactant is $4-hydroxy-3-methylbenzenesulfonic acid$. The reaction with $Br_2$ in $H_2O$ (bromine water) is an electrophilic aromatic substitution. The $-OH$ group is strongly activating and ortho/para directing. The $-SO_3H$ group is a good leaving group in the presence of excess bromine water. Predict the product of the reaction: $\xrightarrow{Br_2, H_2O} \text{Product}$

Salicylaldehyde on heating with zinc dust gives . . . . . . as the organic product.

Phenol is heated with a solution of a mixture of $KBr$ and $KBrO_3$. The major product obtained in the above reaction is:

Phenol on heating with $CHCl_3$ and $NaOH$ gives salicylaldehyde. The reaction is called