Which of the following is the strongest Bronsted acid?

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

In which of the following compounds is deoxygenation possible when heated with $Zn$ dust?

Phenol is less acidic than

Heating benzoic acid with $X$ and phenol with $Y$ gives benzene. $X$ and $Y$ are respectively:

What is the product formed when phenol reacts with $Br_2$ in $CCl_4$ at low temperature?