Question

Alkanes with even number of C atoms have higher melting points than those with odd number of C atoms.

• A. True
• B. False

Answer 1

The correct option is A True

Melting point: Melting point of alkanes increases with increase in carbon content. Alkalies with even number of C atoms have higher melting points than those with odd number of C atoms. This property is called the alternation effect. This can be explained as below:
In n-alkane, due to $s{p}^3$ hybridisation, C atoms are arranged in a zig-zig chain. So, n-alkanes With even number of C atoms are more symmetrical than those containing odd number of C atoms and, hence, can pack closely in the crystal lattice. For example,


Alternation effect is not observed in boiling points because in the liquid state the conformation of the molecules are fixed but keep on changing as a result of collisions