Arrange the following compounds 2-Methylhexane in order of their increasing of (A) boiling point and (B) melting point ? (1) n-hexane (2) 2-methyl hexane (3) 2, 2-dimethyl pentane (4) 2, 3-dimethyl pentane.

(A) BoiIing point on alkane is directly proportional to their molecular weight and  inversely proportional to branching. Therefore, the increasing order is (1) < (3) < (4) < (2)   

(B) Melting point of alkane is directly proportional to molecular weight as well as branching of  alkane because increased branching leads to a more compact molecule. Thus the increasing order is (1) < (2) < (4) < (3).