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 the shape of a 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.
Both Statement I and Statement II are incorrect.
Statement I is correct but Statement II is incorrect.
Statement I is incorrect but Statement II is correct.
Both Statement I and Statement II are correct.
According to the NCERT text, the boiling point of alkanes decreases with an increase in branching. For the isomeric pentanes, n-pentane has a continuous chain of five carbon atoms and the highest boiling point (309.1 K), while the highly branched neopentane (2,2-dimethylpropane) has the lowest (282.5 K), making the order n-Pentane > Isopentane > Neopentane correct . With an increase in the number of branched chains, the molecule attains the shape of a sphere. This results in a smaller area of contact and therefore weak intermolecular van der Waals forces between the spherical molecules, which are overcome at relatively lower temperatures, thereby lowering the boiling point . Therefore, both Statement I and Statement II are true.
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