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(b) Figure 3 shows the average concentration of pollutants NO and NO in an urban area
2
during a 24–hour period.
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Figure 3: Concentration of NO and NO 2
(i) Using the following equilibrium reaction
N (g) + O (g) 2NO (g); ∆H = +180 kJ mol −1
2
2
account for the formation of NO(g) as a pollutant in urban areas.
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[2 marks]
(ii) Suggest a reason for the time lapse between maximum concentrations of NO(g)
and NO (g) shown in Figure 3.
2
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[1 mark]
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