Arrange the following in decreasing order of their boiling point:
Choose the correct options from the following
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → I > II > III
The three compounds have nearly the same molar mass: ethanol \( \ce{C2H5OH} \) (46), methoxymethane \( \ce{CH3OCH3} \) (46) and propane \( \ce{C3H8} \) (44).
I. Ethanol (b.p. 351 K) has intermolecular hydrogen bonding, so it boils highest.
II. Methoxymethane (b.p. 248 K) is polar (dipole-dipole attraction) but cannot form hydrogen bonds between its own molecules.
III. Propane (b.p. 231 K) is non-polar, with only weak van der Waals forces.
NCERT (2026-27 edition):
Physical Properties – …
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| – | – | – | 02-06 S3 31-05 S1 | – |