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 is having 5 carbon atoms.

2. Hence, the word root is pent.

3. Now, it is saturated. Hence, we get pentane.

4. There is an alcohol group in the 3^rd carbon.

5. Hence e is removed from pentane and ol is added prefixed by its position.

6. Hence, the IUPAC name is pentan-3-ol.