Question

which of following has highest boiling point and why? 1) 2-methyl pentane 2) 2,3-dimethylbutane 3) 2,2-dimethylbutane

Answer 1

More the surface area more will be the boiling point. The surface area decreases with branching and is having lower boiling point.
Surface area is in the order
2-methyl pentane > 2,3- dimethyl butane > 2,2-dimethyl butane
Thus 2-methyl pentane is having the highest boiling point.