Which acid would you expect to be stronger ?
`CH_(3)COOH` or `HCOOH`

Explanation

`underset("Formic acid")(H-overset(O)overset(||)(C)-O-H)`
Methyl group in acetic acid has +I effect. It will increase the electron density on oxygen. As such release of `H^(+)` ion from acetic acid will be more difficult as compared to formic acid. Further +I effect of methyl group will destabilize the acetate ion relative to formate ion intensifying -ve charge on carboxylate ion. Hence `H^(+)` will be more difficult to relase from acetic acid than from formic acid. Hence formic acid is a stronger acid than acetic acid.