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Question: Answered & Verified by Expert
Assertion : $\mathrm{CH}_3 \mathrm{OCH}_3$ and $\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}$ has comparable molecular weight but boiling point of $\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}$ is more than dimethyl ether.
Reason : $\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}$ forms intermolecular Hbonding while $\mathrm{CH}_3 \mathrm{OCH}_3$ forms intramolecular $\mathrm{H}$-bonding.
ChemistryChemical Bonding and Molecular StructureAIIMSAIIMS 2001
Options:
  • A If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  • B If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
  • C If Assertion is true but Reason is false.
  • D If Assertion is false but Reason is true.
Solution:
2490 Upvotes Verified Answer
The correct answer is: If Assertion is true but Reason is false.
Due to the presence of hydroxyl group $(-\mathrm{OH})$, there is extensive hydrogen bonding between the ethanol molecules $\left(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}\right)$. But there is no such hydrogen bonding in dimethyl ether (due to absence of -OH group). So boiling point of dimethyl ether is much lower than ethanol.

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