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WAEC Chemistry 2023 Paper

Question : 1

Total: 50

The vapour density of an organic compound with the molecular formula

\mathrm{C}_2\mathrm{H}_4\mathrm{O}_2

[ \mathrm{H}=1.0, \mathrm{C}=12.0, \mathrm{O}=16.0 ]

Validate

Solution:

Concept:

Vapour density is the mass of a certain volume of vapour compared to the same volume of hydrogen. It is equal to half the relative molecular mass of the compound.

Explanation:

For the organic compound

\mathrm{C}_2\mathrm{H}_4\mathrm{O}_2

, first find the relative molecular mass (RMM).

Carbon:

2 \times 12 = 24

Hydrogen:

4 \times 1 = 4

Oxygen:

2 \times 16 = 32

So, RMM

= 24 + 4 + 32 = 60

Vapour density

= \dfrac{\text{RMM}}{2} = \dfrac{60}{2} = 30

Answer:

Vapour density

= 30

, so the correct option is D.

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