Chemistry - STRUCTURAL ISOMERISM Question with Solution | TestHub

Butanal, $\mathrm{C}{\mathrm{H}}_3-\mathrm{C}{\mathrm{H}}_2-\mathrm{C}{\mathrm{H}}_2-\mathrm{CHO}$, and 2-methylpropanal, ($\mathrm{C}{\mathrm{H}}_3{)}_2\mathrm{CH}-\mathrm{CHO}$, are both ${\mathrm{C}}_4{\mathrm{H}}_8\mathrm{O}$ ✓. Ethyl ethanoate, $\mathrm{C}{\mathrm{H}}_3-\mathrm{COO}-\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_3$, is ${\mathrm{C}}_4{\mathrm{H}}_8{\mathrm{O}}_2$ - it contains two oxygens, so it is not an isomer of ${\mathrm{C}}_4{\mathrm{H}}_8\mathrm{O}$. Hence (1) and (3) only.