O-LevelChemistryStoichiometry5070/12 · Oct/Nov 2021 · Q121 Mark

When gases react, the volume of gaseous reactants may be different from the volume of gaseous products. For which reaction is the percentage change in the volume of gas largest? (Assume each reaction goes to completion.)

A2SO2(g) + O2(g) → 2SO3(g)

BCH4(g) + 2O2(g) → CO2(g) + 2H2O(g)

CN2(g) + 3H2(g) → 2NH3(g)

D2C2H6(g) + 7O2(g) → 6H2O(g) + 4CO2(g)

✓ Correct answer

C: N2(g) + 3H2(g) → 2NH3(g)

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Topic: Stoichiometry, O-Level Chemistry (syllabus 5070). Multiple choice, 1 mark.
Source: O-Level Chemistry, Oct/Nov 2021 Paper 1 Variant 2, question 12.

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