Answer:
1) ignition temperature- the minimum temperature that is required to start or cause combustion.
2) combustion - a chemical process in which a substance reacts rapidly with oxygen and gives off heat.
3) fuel - material such as coal, gas, or oil that is burned to produce heat or power.
4) calorific value of a fuel - the quantity of heat produced by its combustion – at constant pressure and under “normal” (standard) conditions