(a)[1]
Air is made up of nitrogen, oxygen, noble gases and carbon dioxide. State the percentage of nitrogen present in clean, dry air.
(b(i))[1]
Give one origin of oxides of nitrogen in the air.
(b(ii))[1]
State one harmful effect of oxides of nitrogen on health.
(c(i))[1]
Name one further element present in most fertilisers.
(c(ii))[1]
Explain why farmers apply fertilisers to fields where crops will be grown.
(c(iii))[2]
Describe a test for potassium ions. test method … observations …