WAEC Chemistry 2014 Paper

Concept:Thermal electric power stations produce nitrogen oxides due to high-temperature combustion of air.Explanation:At the high temperature inside an electric power station, nitrogen and oxygen from air combine to form nitrogen(II) oxide, nitric oxide ($\mathrm{NO}$).This nitric oxide is further oxidized in the atmosphere to nitrogen(IV) oxide ($\mathrm{NO}_2$).Nitrogen(IV) oxide is therefore a common pollutant released from thermal power-generating plants.Sulphur(IV) oxide ($\mathrm{SO}_2$) would be formed only if the fuel contains sulphur.However, Nigerian crude oil is essentially sulphur-free, so sulphur(IV) oxide is not the expected oxide from such power stations.Answer:C. nitrogen (IV) oxide ($\mathrm{NO}_2$)