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JAMB Chemistry 2020 Paper

Question : 18

Total: 40

^3

^{3}

]

Solution:

Concept:

The relative molecular mass is the mass of one mole of the gas, which occupies

22.4\ \mathrm{dm}^3

at S.T.P.

Explanation:

Convert the given volume to

\mathrm{dm}^3

500\ \mathrm{cm}^3 = 0.5\ \mathrm{dm}^3

This means

0.5\ \mathrm{dm}^3

of the gas has a mass of

1.58\ \mathrm{g}

To find the mass of

22.4\ \mathrm{dm}^3

(one mole), use proportion:

\text{Relative molecular mass} = \frac{22.4}{0.5} \times 1.58

= 44.8 \times 1.58 = 70.784 \approx 71

Therefore, the relative molecular mass of the gas is

71

Answer:

D. 71

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