F. Answer the following questions in brief. 1. Why should we use fossil fuels judicially?
3. Define the term 'fossil fuel. Give two examples.
4. How can we conserve fossil fuels?
5. What is calorific value of a fuel?
6. What are conditions required for the formation of fossil fuels?
2. Give full form of CNG. Why is it preferred over other fossil fuels?

1. fossil fuels should be used judiciously as they can be exhausted if used excessively and will take time to replenish

2. fossil fuels are fuel formed by natural processes such as decomposition of dead organisms .

3. They can be easily exhausted

4.The calorific value of a fuel is the quantity of heat produced by its combustion i.e at constant pressure and under “normal” (standard) conditions (i.e. to 0 degree C and under a pressure of 1,013 mbar).

5. COMPRESSED NATURAL GAS . CNG preferred than fossil fuel because it produce greenhouse gases upon combustion, it is a more environmentally clean alternative to other fossil fuels

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs