Answer
Ignoring ring compounds, there are two no. of isomers possible having molecular formula $C_{2}H_{4}O_{2}$ which are; ethanoic acid and methyl methanoate. Between these, methyl methanoate should boil at the lowest temperature i.e. boiling point low. On the other hand, ethanoic acid will have higher boiling point.
Work Step by Step
Considering intermolecular H bond between same molecules of ethanoic acid, it will have higher boiling point than $HCOOCH_{3}$. H bond occurs between molecules when H is bonded with more electronegative atom like N,O,F. Here, H is bonded with O atom. So, H bond is possible between molecules which can be seen below.
On the other hand, for $HCOOCH_{3}$ H is bonded with C atom so H bonding does not occur between molecules.
