Question

Given below are two statements :
Statement I : The boiling point of three isomeric pentanes follows the order
n-pentane > isopentane > neopentane
Statement II : When branching increases, the molecule attains a shape of sphere. This results in smaller surface area for contact, due to which the intermolecular forces between the spherical molecules are weak, thereby lowering the boiling point.
In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Both Statement I and Statement II are correct.
• B. Both Statement I and Statement II are incorrect.
• C. Statement I is correct but Statement II is incorrect.
• D. Statement I is incorrect but Statement II is correct.

Answer 1

The Correct Option is A

Statement I details the boiling points of three pentane isomers: n-pentane, isopentane, and neopentane, with the order n-pentane > isopentane > neopentane. This is accurate; boiling point correlates with surface area for intermolecular forces. n-Pentane, being linear, possesses the largest surface area, leading to stronger van der Waals forces and a higher boiling point than its branched counterparts.

Statement II elucidates how branching alters molecular shape and boiling point. Increased branching results in a more spherical molecular shape, reducing the surface area available for intermolecular forces such as van der Waals forces. This diminished surface area weakens these forces, consequently lowering the boiling point. This statement accurately characterizes molecular behavior and its effect on boiling point.

As both statements correctly articulate the connection between molecular structure and boiling point, the appropriate conclusion is: Both Statement I and Statement II are correct.