Explain why the atmosphere near power stations that burn fossil fuels may contain high concentrations of $\text{SO}_2$.
The $\text{SO}_2$ released can be turned in the atmosphere into sulfuric acid, $\text{H}_2\text{SO}_4$, through reaction with nitrogen dioxide gas, $\text{NO}_2$, and water, $\text{H}_2\text{O}$. The reactions are: $\text{SO}_2 + \text{NO}_2 \rightarrow \text{NO} + \text{SO}_3$ $\text{SO}_3 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{SO}_4$ In one year, a fossil-fuel power station emitted 1590 tonnes of $\text{SO}_2$ into the atmosphere. Use the equations to work out how many tonnes of $\text{H}_2\text{SO}_4$ were produced in the atmosphere. Assume that every bit of the $\text{SO}_2$ released was changed into $\text{H}_2\text{SO}_4$.
Describe how $\text{NO}_2$ is also formed by these power stations.
State one natural cause of $\text{NO}_2$ forming in the atmosphere.
Explain why $\text{NO}_2$ may be described as a catalyst in the oxidation of atmospheric $\text{SO}_2$.