The table shows the boiling points of four different hydrocarbon molecules present in crude oil.
\begin{array}{|c|c|} \hline \text{Hydrocarbon} & \text{Boiling Point } (^\circ\text{C}) \\\ \hline \text{W} & -161 \\\ \hline \text{X} & 36 \\\ \hline \text{Y} & 174 \\\ \hline \text{Z} & 343 \\\ \hline \end{array}
Which hydrocarbon, W\text{W}W, X\text{X}X, Y\text{Y}Y, or Z\text{Z}Z, is most likely to be collected in the refinery gas fraction at the very top of a fractionating column? Explain your choice.
A transport company is deciding between using Bio-CNG (compressed natural gas) buses or hydrogen fuel cell buses. The table below shows information about a 300 km300\text{ km}300 km route for both types of bus:
\begin{array}{|c|c|c|} \hline \text{Feature} & \text{Bio-CNG Bus} & \text{Hydrogen Fuel Cell Bus} \\\ \hline \text{Refuelling time (minutes)} & 10 & 15 \\\ \hline \text{Cost of fuel per } 300\text{ km (£)} & 95.00 & 140.00 \\\ \hline \text{CO}_2\text{e emitted (kg)} & 85 & 0 \\\ \hline \text{Mass of bus (kg)} & 11\,000 & 13\,500 \\\ \hline \end{array}
Evaluate the advantages and disadvantages of choosing the hydrogen fuel cell bus instead of the Bio-CNG bus for this route. Use the data in the table to support your response.