Question

In alkane on increasing molecular weight, melting point and boiling point increases

Answer 1

As the number of carbon atoms increase, the amount of heat required to break the bonds also increases. Thus the melting point and boiling point of an alkane increases with increase in number of carbon atoms.

Example
Melting point. Boiling point
Methane 90 k 111 k
Ethane 90.4 k 180.6 k