JAMB Chemistry 2022 Paper

Concept:The empirical formula shows the simplest whole-number ratio of atoms in a compound.This ratio is obtained by converting percentage masses to moles.Explanation:Assume a $100$ g sample of the compound.So the masses are: $69$ g carbon, $15.3$ g hydrogen, and $30.7$ g oxygen.Convert each mass to moles using the given atomic masses.For carbon: $\frac{69}{12} = 5.75$ mol.For hydrogen: $\frac{15.3}{1} = 15.3$ mol.For oxygen: $\frac{30.7}{16} = 1.92$ mol.Divide each mole value by the smallest value, $1.92$.Carbon: $\frac{5.75}{1.92} \approx 3$Hydrogen: $\frac{15.3}{1.92} \approx 8$Oxygen: $\frac{1.92}{1.92} = 1$So the simplest ratio is $C:H:O = 3:8:1$.Answer:The empirical formula is $\mathrm{C}_3\mathrm{H}_8\mathrm{O}$.Therefore, the correct option is D.