O-LevelChemistryRates of Reaction5070/12 · May/June 2018 · Q211 Mark

Nitrogen reacts with oxygen in an equilibrium reaction. N₂(g) + O₂(g) ⇌ 2NO(g) ΔH = +170 kJ/mol When the reaction is at equilibrium, which statement is correct?

AThe concentration of nitrogen present will change with time.

BThe forward and backward reactions are taking place at the same rate.

CThe forward reaction releases heat energy.

DThere are more molecules on the left hand side of the equation than on the right.

✓ Correct answer

B: The forward and backward reactions are taking place at the same rate.

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Topic: Rates of Reaction, O-Level Chemistry (syllabus 5070). Multiple choice, 1 mark.
Source: O-Level Chemistry, May/June 2018 Paper 1 Variant 2, question 21.

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