Question

How do you draw the condensed structural formulas of four structural isomers of the carboxylic acids that have the molecular formula `C_5H_10O_2`?

Answer 1

The isomers of compound having molecular formula `C_5H_10O_2` should contain `-COOH`.So it contains `C_4H_9-` as alkyl group.
Depending on the structures of alkyl groups there are following isomers of carboxylic acids with their condensed formulae.

1.Sraight chain of 4 C-atom

`CH_3CH_2CH_2CH_2COOH->"Pentanoic acid"`

2.One methyl group as branch at C-2

`CH_3CH_2(CH_3)CHCOOH->"2-methylbutanoic acid"`

3.One methyl group as branch at C-3

`CH_3(CH_3)CHCH_2COOH->"3-methylbutanoic acid"`

4.Two methyl groups as branches at C-2

`(CH_3)_3C.COOH->"2,2-dimethylpropanoic acid"`