Write down the IUPAC names of the compounds given.

The IUPAC names of the given compounds with proper numbering of the main chain and the substituents keeping in mind the fact that the numbering is done so as to choose the longest branch of carbon and giving the carbon bearing the substituent or the functional group the lowest number as possible are as follows: -

1. At first we find the longest chain of the carbon atom. Here, the longest chain constituents of 6 carbon atoms and it is a saturated hydrocarbon. Hence, the word root is hexane.

2. Now upon numbering we find that the substituent which is the methyl group here is attached at the 3^rd carbon.

3. Hence, the name derived is 3-methylhexane.