JEE MainChemistryAlcohols Phenols and Ethers
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : The boiling point of n-butyl alcohol is higher than that of tert-butyl alcohol, but both have higher boiling points than diethyl ether. Reason (R) : Boiling points of alcohols decrease with an increase in branching due to a decrease in surface area, while alcohols have higher boiling points than
Options
- ABoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- BBoth (A) and (R) are correct and (R) is the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
B. Both (A) and (R) are correct and (R) is the correct explanation of (A)
Step-by-step solution
Assertion (A) is correct. n-butyl alcohol is a straight-chain alcohol and tert-butyl alcohol is its branched isomer. Both are alcohols and have higher boiling points than diethyl ether, which is an ether of comparable molecular mass. Reason (R) is also correct and provides the exact physical explanation for the Assertion. For isomeric alcohols, as branching increases, the molecule becomes more spherical, which decreases the surface area and consequently weakens the van der Waals forces. This explains why n-butyl al