8th Class Science: Coal and Petroleum

Carbonisation and Coal

• Carbonisation is the slow process of converting dead vegetation into coal, which mainly contains carbon.
• Coke is a tough, porous, and black substance that is an almost pure form of carbon.
• Uses of coke: manufacturing steel, extracting metals, and as a fuel.

Natural Resources

• Natural resources are substances present on the earth that allow the existence of life and satisfy the needs of living organisms.
• Inexhaustible natural resources: unlimited quantity, not likely to be exhausted by human activities (e.g., sunlight, air, and water).
• Exhaustible natural resources: limited quantity, likely to be exhausted by human activities (e.g., forests, wildlife, minerals, coal, petroleum, and natural gas).

Formation of Coal

• Coal was formed around 300 million years ago from dense forests in low-lying wetland areas.
• Natural processes like flooding buried these forests under soil, compressing them, and increasing temperature.
• Under high temperature and pressure, dead plants converted into coal.

Fossil Fuels

• Fossil fuels require millions of years to form from dead plants and animals.
• Amount of fossil fuels in nature is limited, making them exhaustible resources.

Advantages of CNG and LPG

• CNG and LPG can be burnt directly and easily transported through pipelines.
• They have higher calorific value than other fuels and are cleaner fuel, burning without smoke.

Coal Tar

• Coal tar is a thick, black liquid with an unpleasant smell and a mixture of about 200 carbon compounds.
• Uses of coal tar: making synthetic dyes, drugs, explosives, perfumes, plastics, paints, and roofing materials.

Formation of Petroleum

• Petroleum was formed from organisms living in the sea, which settled at the bottom and got covered with layers of sand and clay.
• Over millions of years, dead organisms converted into petroleum and natural gas under high pressure and temperature.
• Petroleum and natural gas get trapped between two layers of rocks, with natural gas collecting above petroleum under high pressure.

Refining of Petroleum

• Refining of petroleum is the process of separating various constituents or fractions of petroleum.

Quiz on Chapter 3 of 8th class Science, covering topics related to coal and petroleum, including carbonisation and characteristics of coke.