HVZ reaction involves the use of $\mathrm{P}$ and ${\mathrm{Cl}}_2$

${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{COOH}\stackrel{\mathrm{P},{\mathrm{Cl}}_2}{⟶}{\mathrm{CH}}_3\mathrm{CHClCOOH}$

The function of phosphorus is

Salicylic acid is treated with bromine under two different conditions.

Predict the nature of $\left[\mathrm{X}\right]$ and $\left[\mathrm{Y}\right]$ in the above reactions.

Among the following compounds, the most acidic is:

.

Given three acids:

The correct order of ease of acid catalysed esterification is:

${\mathrm{C}}^{*}$ is within the product: