The figure shows how much of each of four fractions is obtained from crude oil, and how much of each fraction is needed.
Figure: The percentage of crude oil that is each of four fractions and the percentage of the total demand for each fraction

Use the figure. Name the fraction for which the demand is greater than the amount obtained from crude oil.
Use the figure. Name the fraction that is obtained in the largest excess.
Explain how cracking helps the oil industry to match what it produces to what is needed.
Cracking also produces alkenes. Give one use of alkenes.