(a)[1]
What percentage by volume of nitrogen is present in dry air?
(b)[3]
Outline how oxygen, nitrogen and the noble gases are separated from liquid air.
(c)[1]
State one large-scale use of nitrogen.
(d(i))[1]
Name one gas that helps to cause acid rain.
(d(ii))[1]
State one environmental consequence caused by an increase in the percentage of carbon dioxide in the air.
(d(iii))[1]
Describe where carbon monoxide in air comes from.