Calorific value and ignition temperature of fuel X are 75 kJ/g and 200C respectively. These values for fuel Y are 50 kJ/g and 750C respectively. On burning, the fuel Y produces only CO2 while fuel X produces CO2 and CO. Which of the two is a better fuel? Give two reasons to support your answer.

Fuel Y is a better fuel due to the following main reasons:

(i) Y has a moderate ignition temperature of 75°C

(ii) As it do not produce any harmful gas (like CO) while burning.