CBSE Class 12-science Answered

2,2-Dimethylpropane>2-methylbutane>pentane

The melting points of branched-chain alkanes can be either higher or lower than those of the corresponding straight-chain alkanes, again depending on the ability of the alkane in question to packing well in the solid phase. Where we have isomers, the more branched the chain, the higher the melting point tends to be. Vander Waals dispersion forces are smaller for shorter molecules, and only operate over very short distances between one molecule and its neighbors.