Explanation:
butanoic acid has four carbon atoms, with last carbon being the carbonyl carbon
[tex]{ \tt{CH _{3}CH _{2}CH _{2} C OOH}}[/tex]
• chlorine molecule is on the third carbon from the right hand side [ carboxylic group side ]
[tex]{ \tt{CH _{3}CH(Cl) _{}CH _{2} C OOH}}[/tex]
• hydroxyl molecule is on the fourth carbon fromright hand side.
[tex]{ \tt{(OH)CH _{2}CH(Cl) _{}CH _{2} C OOH}}[/tex]
