MHTCET 10 May 2024 Shift 2 Paper

Concept:More branching in an alcohol lowers its boiling point due to decreased surface area and weaker van der Waals forces.Explanation:The four isomeric alcohols of formula $\mathrm{C}_4\mathrm{H}_9\mathrm{OH}$ differ only in the arrangement of the carbon skeleton.Boiling point depends on the strength of intermolecular forces between molecules.A straight-chain structure provides a larger surface area for intermolecular contact.This leads to stronger van der Waals forces and a higher boiling point.As branching increases, the molecular shape becomes more compact, reducing surface area.Therefore, $\text{Boiling point} \propto \frac{1}{\text{Branching}}$.n-Butyl alcohol is the unbranched, straight-chain isomer.Isobutyl, sec-butyl, and tert-butyl alcohols are increasingly branched.Hence, n-butyl alcohol shows the strongest intermolecular forces and has the highest boiling point.The order of boiling points is: $\text{n-butyl} > \text{isobutyl} > \text{sec-butyl} > \text{tert-butyl}$.Answer:n-Butyl alcohol (Option A)