Statement I : The boiling point of three isomeric pentanes follows the order n-pentane > isopentane > neopentane

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: 

(1) Both Statement I and Statement II are correct 

(2) Both Statement I and Statement II are incorrect 

(3) Statement I is correct but Statement II is incorrect 

(4) Statement I is incorrect but Statement II is correct

Answer 1

Correct option is (1) Both Statement I and Statement II are correct 

Both statement I and statement II are correct. 

Boiling point of n-pentane = 309 K 

isopentane = 301 K 

neopentane = 282.5

As branching increases molecules attain the shape of a sphere results in smaller area of contact thus weak intermolecular forces between spherical molecules, which are overcome at relatively lower temperature. Leading to decrease in boiling point.