Question

In the series of `n`-alkanes, the melting point of an unbranched alkane with an even number of `C` atoms is much…..than the previous unbranched alkane with an odd number of `C` atoms but slightly……than the succeeding unbranched alkane with an odd number of `C` atoms.
A. lower, lower
B. higher,higher
C. higher,lower
D. lower, higher

Answer 1

Correct Answer - C
Order of melting points
`{:("Pentane",lt,"Hexane",lt,"Heptane"),(143.3K,,178.5K,,182.K):}`
This is because alkanes chains with an even number of `C` atoms pack more closely in the crystalline state.