JAMB Chemistry 2018 Paper

Concept:Vapour density is the ratio of the mass of a given volume of a gas to the mass of the same volume of hydrogen at the same temperature and pressure.It equals half the molecular mass because the molecular mass of hydrogen is $2$.Explanation:Vapour density is calculated using the formula:$$\text{Vapour density} = \frac{\text{Molecular mass}}{2}$$The molecular mass of tetraoxosulphate (VI) acid, $\mathrm{H}_2\mathrm{SO}_4$, is given as $98$.Substitute $98$ into the formula:$$\text{Vapour density} = \frac{98}{2} = 49$$Vapour density has no units because it is a ratio.Answer:The correct answer is B. $49$.