O-LevelChemistryRates of Reaction5070/12 · May/June 2017 · Q151 Mark

The formation of liquid water from hydrogen and oxygen may occur in three stages. 1 2H₂(g) + O₂(g) → 4H(g) + 2O(g) 2 4H(g) + 2O(g) → 2H₂O(g) 3 2H₂O(g) → 2H₂O(l) Which stages would be exothermic?

A1, 2 and 3

B1 and 2 only

C2 and 3 only

D2 only

✓ Correct answer

C: 2 and 3 only

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Topic: Rates of Reaction, O-Level Chemistry (syllabus 5070). Multiple choice, 1 mark.
Source: O-Level Chemistry, May/June 2017 Paper 1 Variant 2, question 15.

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