Name the pollutant with the greatest concentration in 2019.
Name the pollutant whose concentration decreases continuously from 2019 to 2022.
Calculate the average mass, in ng, of hydrocarbons in a 200 cm$^3$ sample of polluted air in 2019.
State one source of oxides of nitrogen in air.
Oxides of nitrogen contribute to acid rain. Give one other effect of oxides of nitrogen in the air.
Unpolluted water has a neutral pH. From the list, choose the pH value of a neutral substance, then draw a circle around your choice. pH1 pH6 pH7 pH14
Nitrogen dioxide is an acidic oxide. From the list, choose an oxide that is also acidic. Tick (✓) one box. copper(II) oxide magnesium oxide phosphorus(V) oxide sodium oxide
Complete the symbol equation for this reaction. $\ldots\text{SO}_2 + \ldots\ldots\ldots\rightleftharpoons 2\text{SO}_3$
State what the symbol $\rightleftharpoons$ means.
Describe a test for sulfate ions. test .................... observations ....................