(A) What are fossil fuels? Give three examples of fossil fuels.(B) Describe how fossil fuels were formed.(C) Explain how much sun is considered to be the ultimate source of fossil fuels.(D) Which fossil fuels were formed by the buried remains of small plants and animals?(E) Which fossil fuel was formed by the buried remains of large land plants?

Hint: As per principle of conservation of energy, energy can neither be created nor destroyed but can be transformed from one form to another. But a good source of energy is the one that can be used again and again for a long time. While choosing for a source of energy to do any work, many factors are considered like whether it is easily available, is it cheap etc. Complete solution: (A) The fossil fuels are a source of energy. They are also known as non-renewable sources of energy. The examples of fossil fuels are- Coal, petroleum and natural gas. (B) The fossil fuels were formed by the dead remains of plants and animals that were buried under Earth millions of years ago. They are formed because of high pressure and high temperature. (C) It is already mentioned that fossil fuels are formed inside the Earth from the remains of plants and animals. When these plants and animals were alive, they used to get their energy and food from sunlight. But later on, fossil fuels were formed from them. So, the sun is considered as the ultimate source of energy. (D) Fossil fuels like natural gas, fuel oil and petroleum are formed by the dead remains of plants and animals. (E) Coal was formed by the buried remains of large land plants. Note: It is to be noted that though fossil fuels are considered as the conventional source of energy but they are to be used very carefully and wisely. This is because if over consumption of fossil fuels is done, then they will soon run out of energy as they are non-renewable. Therefore, alternate sources of energy should be used.