4-Nitrophenol is much more soluble in water than 2-nitrophenol. This is because

A4-nitrophenol is non-polar
B2-nitrophenol has no hydroxyl group
C2-nitrophenol has an intramolecular hydrogen bond, while 4-nitrophenol hydrogen-bonds with water
D2-nitrophenol is more acidic and ionises completely

Answer: C

In 2-nitrophenol the

O - H

and the adjacent

NO X_{2}

are close enough to form an intramolecular hydrogen bond, so the hydroxyl is unavailable for water. In 4-nitrophenol this is impossible, and the

OH

and

NO X_{2}

groups hydrogen-bond with water, which raises solubility.