Question

The vapor pressure of o-nitrophenol at any given temperature is predicted to be-
(1) higher than that of p-nitrophenol
(2) lower than that of p-nitrophenol
(3) same as that of p-nitrophenol
(4) higher or lower depending upon the size of the vessel​

Answer 1

Since p nitrophenol forms intermolecular hydrogen bond so, associate mass increases .

So vapour presssure at any temperature will be lesser for o-nitrophenol because it does not form intermolecular hydrogen bond hence its associate mass does not increase.

(2) will be the answer.

Hope it helps