Release of sulfur dioxide, SO2, into the atmosphere causes acid rain. (a) Explain why high levels of SO₂ may be found in the atmosphere near power stations that burn fossil fuels. [2] (b) The SO2 released can be converted in the atmosphere into sulfuric acid, H2SO4, by reaction with nitrogen dioxide gas, NO2, and water, H₂O. SO₂ + NO2 → NO + SO3 SO3 + H2O → H2SO4 During one year, 1590 tonnes of SO2 was released into the atmosphere by a fossil-fuel burning power station. (i) Use the equations to calculate how many tonnes of H₂SO₄ were formed in the atmosphere. Assume that all of the SO2 released was converted into H2SO4. mass of H2SO4 = tonnes [2] (ii) Describe how NO2 is also produced by these power stations. [2] (iii) State one natural cause of NO2 being formed in the atmosphere. [1] (iv) Explain why NO2 can be described as a catalyst in the oxidation of atmospheric SO2. [2] [Total: 9]