Which among the following compounds is most soluble in water ?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Ethylene glycol
The solubility of alcohols and phenols in water is due to their ability to form hydrogen bonds with water through the –OH group, while the hydrocarbon part resists dissolving. So the more –OH groups a molecule has for the size of its hydrocarbon part, the more soluble it is.
Ethylene glycol, \( \ce{HOCH2CH2OH} \): two –OH groups on a two-carbon chain; it mixes with water in all proportions and forms more hydrogen bonds than ethanol, so it is the most soluble of the four.
Ethanol, \( \ce{C2H5OH} \): one –OH group; also miscible with water, but with fewer hydrogen bonds per molecule.
Phenol, \( \ce{C6H5OH} \): one –OH group on a large, hydrophobic benzene ring; only moderately soluble.
Ethane, \( \ce{C2H6} \): no –OH group, no hydrogen bonding; almost insoluble.
So the most soluble compound is ethylene glycol.
NCERT (2026-27 edition):
Solubility
