Which of the following is a pair of dihydric phenols?

Which of the following is the least acidic?

In which of the following,ortho/para substitution by an electrophile is very facile?

Write the chemical equations for the following reactions:
$(i)$ Reimer-Tiemann reaction
$(ii)$ Kolbe's reaction

Phenol reacts with $CO_2$ in the presence of sodium hydroxide followed by acidification to give a steam volatile compound $X$. The compound $X$ on treatment with acetic anhydride in the presence of a catalytic amount of $H_2SO_4$ produces $Y$. Among the following:
$(i)$ antipyretic
$(ii)$ anti-inflammatory
$(iii)$ narcotic analgesic
$(iv)$ antiplatelet
the properties shown by compound $Y$ are

Phenol can be distinguished from ethanol by the reagent