The product $(A)$ is

Which intermediate is formed in the Reimer-Tiemann reaction?

Arrange the following compounds in order of decreasing acidity:

What amount of bromine will be required to convert $2 \ g$ of phenol into $2, 4, 6-$tribromophenol (in $g$)? $($Given molar mass in $g \ mol^{-1}$ of $C, H, O, Br$ are $12, 1, 16, 80$ respectively$)$

Heating phthalic anhydride and concentrated sulfuric acid with which of the following yields phenolphthalein?

Identify the correct set from the following:

Compound

$p K_a$