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2020 H2 Chem P1 Q20 — Alkane Solution

Alkane 2020 A-Level H2 Chemistry · Paper 1 · Q20

Question

Exhaust fumes from car engines contain the gases carbon dioxide, nitrogen oxides and unburnt hydrocarbons.
Use of a catalytic converter in the car exhaust changes the gases emitted.
Which statements are correct about the reactions occurring in the catalytic converter?

1) Carbon dioxide is removed by reduction.
2) Oxides of nitrogen are removed by reduction.
3) Unburnt hydrocarbons are removed by oxidation

A1 and 3
B2 and 3
C1 only
D2 only

Correct answer: B

Video Solution

Explanation

The answer is B (2 and 3).

• 1 Incorrect. Carbon dioxide is not removed. It is the final product formed when carbon monoxide and unburnt hydrocarbons are oxidised in the converter.
• 2 Correct. Oxides of nitrogen, \(\text{NO}_x\), are converted to \(\text{N}_2\). Removal of O from \(\text{NO}_x\) is reduction.
• 3 Correct. Unburnt hydrocarbons, \(\text{C}_x\text{H}_y\), are converted to \(\text{CO}_2\) and \(\text{H}_2\text{O}\). Addition of O is oxidation.

• A (1 and 3) and C (1 only) include statement 1, which is incorrect.
• D (2 only) leaves out statement 3, which is correct.

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