Scientists have found that nitrogen monoxide is formed is ❌ and engines when nitrogen and oxygen in the air are heated to about ❌ degrees celsius. When the nitrogen ❌ is released into the atmosphere it cools down then reacts with more ❌ to form nitrogen dioxide.
N2 + O2 -> 2❌
2NO + ❌2 -> 2NO2

There are two methods of ❌ gas desulphurisation. The most common method uses ❌ oxide (lime) which is obtained by heating ❌. The lime is mixed with water to make an alkaline ❌. Sulphur dioxide is washed or '❌' out of the flue gases with water and reacts with the lime. The compound formed is reacted with ❌ in the air to make calcium sulphate, which can be sold to make plaster for walls, helping to pay for the process.
The second method uses seawater (naturally slightly alkaline) to react with the sulphur dioxide and act as a ❌. The product is ❌, giving off carbon dioxide. A ❌ volume of seawater has to be used for this process, however.