(a)[1]
State the percentage, by volume, of oxygen in clean, dry air.
(b(i))[1]
The percentage of carbon dioxide in air is increasing. State one harmful effect of this rising percentage of carbon dioxide.
(b(ii))[1]
State one strategy that would slow this increase in the percentage of carbon dioxide.
(c(i))[1]
Some air pollutants, including sulfur dioxide, can lead to acid rain. Name one other air pollutant that causes acid rain.
(c(ii))[1]
Burning sulfur-containing fossil fuels in power stations produces sulfur dioxide emissions. Describe one method used to reduce these sulfur dioxide emissions.