(a(i))[1]
Name the pollutant whose concentration falls from April to July.
(a(ii))[1]
Name the pollutant with the lowest concentration in May.
(a(iii))[1]
Calculate the mass of sulfur dioxide in 250 cm$^3$ of the air sample collected in April.
(b(i))[1]
State one additional source of oxides of nitrogen in the air.
(b(ii))[1]
Give one adverse health effect of oxides of nitrogen.
(b(iii))[2]
Complete the chemical equation for the reaction of nitrogen with oxygen to make nitrogen dioxide. $\dots + 2\text{O}_2 \rightarrow \dots \text{NO}_2$
(c)[1]
State the name used for this random motion of particles.