If the boiling point of methoxymethane is 248 K, which of the following is the most likely boiling point of ethanol?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 351 K
Ethanol (\( \ce{C2H5OH} \)) and methoxymethane (\( \ce{CH3OCH3} \)) are isomers (\( \ce{C2H6O} \)), so they have the same molar mass.
Ethanol has an –OH group and its molecules are held together by intermolecular hydrogen bonds; the ether has no O–H bond and cannot form them.
Ethanol therefore boils well above 248 K: its boiling point is 351 K.
NCERT (2026-27 edition):
7.4.3 Physical Properties – “… For example, ethanol and propane have comparable molecular masses but their boiling points differ widely. The boiling point of methoxymethane is intermediate of the two boiling points. … The high boiling points of alcohols are mainly due to the presence of intermolecular hydrogen bonding in them which is lacking in ethers and hydrocarbons.”
7.5 Some Commercially Important Alcohols – “Ethanol is a colourless liquid with boiling point 351 K.”