NCERT Solutions for Class 8th Science
Chapter 5. Coal And Petroleum
- Petroleum is a dark oily liquid. It has an unpleasant odour. It is a mixture of various constituents such as petroleum gas, petrol, diesel, lubricating oil, paraffin wax, etc.
- These resources are present in unlimited quantity in nature is called Inexhaustible. Examples are: sunlight, air.
- The amount of these resources in nature is limited are called exhaustible. Examples of these resources are forests, wildlife, minerals, coal, petroleum, natural gas etc.
- The dead remains of living organisms (fossils). So, these are all known as fossil fuels.
- As coal contains mainly carbon, the slow process of conversion of dead vegetation into coal is called carbonisation.
- Coke is a tough, porous and black substance. It is almost pure form of
carbon.It is used in the manufacture of steel.
- Coal tar is a black, thick liquid with unpleasant smell. It is a mixture of about 200 substances.
- Petrol and diesel are obtained from a natural resource called petroleum.
- The world’s first oil well was drilled in Pennsylvania, USA, in 1859.
- Great commercial importance, petroleum is also called ‘black gold’.
- The process of separating the various constituents fractions of petroleum is known as refining. It is carried out in a petroleum
- Natural gas is a very important fossil fuel because it is easy to transport through pipes.
- CNG is used as a fuel for transport vehicles because it is less polluting.