Give the reactions of phenol with zinc dust and oxidation.

Which among the following phenols has the highest melting point?

The order of acidic strength of $X, Y$ and $Z$ is:
Phenol reacts with dilute $HNO_3$ to form $X$ ($o$-nitrophenol) and $Y$ ($p$-nitrophenol). Phenol reacts with concentrated $HNO_3$ and $H_2SO_4$ to form $Z$ ($2,4,6$-trinitrophenol or picric acid).

The reactivity of compound $Z$ with different halogens under appropriate conditions is given below:
(Image of reaction: $Z$ ($3$-tert-butylphenol) reacts with $X_2$ to give mono-halo derivative for $X_2 = I_2$,di-halo for $X_2 = Br_2$,and tri-halo for $X_2 = Cl_2$)
The observed pattern of electrophilic substitution can be explained by:
$A$. The steric effect of the halogen
$B$. The steric effect of the tert-butyl group
$C$. The electronic effect of the phenolic group
$D$. The electronic effect of the tert-butyl group

When phenol is heated with zinc dust,it forms product $X$. What is the product $X$?

Which of the following reagents will produce salicylaldehyde on reaction with phenol?