A difficulty linked to the use of shale gas is that its composition varies. Table 1 gives the percentage composition of shale gas from four separate sources J, K, L and M. In the formulae above, $x$ and $y$ are variables. Draw the structures of three possible compounds with the formula $\text{C}_3\text{H}_y$.
Which source of shale gas, J, K, L or M, will give the greatest energy output when burned? Explain your answer.
Suggest two ways in which carbon dioxide can be removed from shale gas.
Table 2 compares the relative amounts of pollutants formed when shale gas, fuel oil and coal are burned to supply the same amount of energy. Suggest why shale gas gives the smallest amount of $\text{CO}_2$.
Explain which of the three fuels, shale gas, fuel oil or coal, contributes most to acid rain.
Suggest a reason why fuel oil and coal produce more $\text{NO}_2$ than shale gas.
State one environmental effect of increased levels of: - $\text{CO}$ - $\text{CO}_2$