JEE Main · 2022 · 27 Jun 2022 · Shift 2 · Some Basic Concepts of Chemistry

The masses translate into $\frac{7.5}{1}=7.5$ mol of hydrogen atoms, $\frac{48.5}{12}\approx 4.0$ mol of carbon and $\frac{60}{16}=3.75$ mol of oxygen, so the atom ratio $\mathrm{C}:\mathrm{H}:\mathrm{O}$ is about $4.0:7.5:3.75$, which reduces to $1:2:1$ and fixes the empirical unit as $\mathrm{C}{\mathrm{H}}_2\mathrm{O}$. A formula is consistent with the data only when it collapses to this same $1:2:1$ ratio: $\mathrm{C}{\mathrm{H}}_3\mathrm{COOH}={\mathrm{C}}_2{\mathrm{H}}_4{\mathrm{O}}_2=(\mathrm{C}{\mathrm{H}}_2\mathrm{O}{)}_2$ qualifies and $\mathrm{HCHO}=\mathrm{C}{\mathrm{H}}_2\mathrm{O}$ qualifies, whereas $\mathrm{C}{\mathrm{H}}_3\mathrm{OOC}{\mathrm{H}}_3={\mathrm{C}}_2{\mathrm{H}}_6{\mathrm{O}}_2$ gives $1:3:1$ and $\mathrm{C}{\mathrm{H}}_3\mathrm{CHO}={\mathrm{C}}_2{\mathrm{H}}_4\mathrm{O}$ gives $2:4:1$, neither of which matches. The number of formulae agreeing with the data is $2$.