Chemistry 0620 · IGCSE · Air quality and climate

Air quality and climate — practice question

The table presents the mass, measured in nanograms, of air pollutants in 1000 cm$^3$ air samples collected during a four month interval.
(a(i))[1]

State which pollutant shows a fall in concentration from August to November.

(a(ii))[1]

Determine the mass of oxides of nitrogen in 250 cm$^3$ of the air sample collected in August.

(b(i))[1]

State what is meant by the term incomplete combustion.

(b(ii))[1]

Give one harmful health effect of carbon monoxide.

(c(i))[1]

Explain the purpose of using a catalyst in this reaction.

(c(ii))[1]

State one source of methane in the atmosphere.

(d(i))[2]

Complete the chemical equation for the reaction between carbon monoxide and oxygen. $\ldots\ldots\text{CO} + \text{O}_2 \rightarrow \ldots\ldots\text{CO}_2$

(d(ii))[1]

Complete the energy level diagram for the reaction of carbon monoxide with oxygen by placing these labels on it: • reactants • products.

(d(iii))[1]

Explain, from the energy level diagram, how you can tell that this reaction is exothermic.

(e(i))[2]

Describe how you could test for carbon dioxide. test result

(e(ii))[1]

Identify which one of these pH values matches the pH of a solution of carbon dioxide in water. Circle the correct choice. pH 6 pH 7 pH 8 pH 14

Worked solution & mark scheme

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