Answer:
Here we have some of the requirement of practical fuel are
1. It must contain large amount of stored energy. So that more amount of power output available to run the engines, motors etc.
2. It must occur in abundance in nature or be easy to produce.
3. The fuel must be made up of elements that combine easily with oxygen. Foe example if hydrogen molecules reacts with oxygen. Then the products are at the reaction of lower energy than the reactants, the result is the explosive release of energy and the product of water.