Write down the IUPAC names of the compounds given.

CH₃—CH₂—CH₂—COOH

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 4 carbon atoms.

2. Hence, the word root is but.

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

4. There is a carboxyl group in the 1^st carbon.

5. Hence e is removed from butane and oic acid is added.

6. Hence, the IUPAC name is butanoic acid.