Science & Technology_12-JUL-2024_p1cDTV3AA.pdf

UDGAM SCHOOL FOR CHILDREN Std. VIII– Science (2024-25) Ch.3: Coal and petroleum Notes Name: ___________________________ Sec: ______ Roll No. _____ Date___________...

UDGAM SCHOOL FOR CHILDREN Std. VIII– Science (2024-25) Ch.3: Coal and petroleum Notes Name: ___________________________ Sec: ______ Roll No. _____ Date___________ 1. What is carbonisation? A. Coal mainly contains carbon. The slow process of conversion of dead vegetation into coal is called carbonisation. 2. Describe the characteristics and uses of coke. A. i. Characteristics: a) Coke is a tough, porous and black substance. b) It is an almost pure form of carbon. ii. Uses: a) Coke is used in the manufacture of steel. b) It is used in the extraction of many metals. c) It is used as a fuel. 3. What are natural resources? A. Natural resources are substances present on the earth that allow the existence of life and satisfy the needs of living organisms. 4. Differentiate between exhaustible and inexhaustible natural resources? Give examples. A. Inexhaustible natural resources Exhaustible natural resources The natural resources which are present The natural resources which are present in unlimited quantity in nature and are in limited quantity in nature and are not likely to be exhausted by human likely to be exhausted by human activities are called inexhaustible natural activities are called exhaustible natural resources. resources. e.g.- sunlight, air and water e.g.- forests, wildlife, minerals, coal, petroleum, natural gas etc. 5. How was coal formed? A. About 300 million years ago the earth had dense forests in low lying wetland areas. - Due to natural processes, like flooding these forests got buried under soil. - As more soil deposited over them, they were compressed. - The temperature also rose as they sank deeper and deeper. - Under high temperature and pressure, dead plants got slowly converted into coal. 6. Explain why fossil fuels are exhaustible natural resources. A. Fossil fuels require millions of years to form from the dead remains of plants and animals which get buried deep inside the earth. - Amount of this source in nature is limited. - Thus, the rate at which fossil fuels are being used, will lead to their exhaustion. Std.-VIII/ Science/ Ch-3/ Notes/ 2024-25 Page 1 of 2 7. What are the advantages of using CNG and LPG as fuel? A. The advantages of using CNG and LPG are - They can be burnt directly. - They can be easily transported through pipelines. - Their calorific value is higher than other fuels. - They are cleaner fuel and burn without smoke. 8. Describe the characteristics and uses of coal tar. A. i. Characteristics: a) Coal tar is a thick black liquid with an unpleasant smell. b) It is a mixture of about 200 carbon compounds. ii. Uses: a) The products of coal tar are used to make synthetic dyes, drugs, explosives, perfumes, plastics, paints, photographic materials, roofing materials, etc. b) It is used to make naphthalene balls. 9. How was petroleum formed? A. Petroleum was formed from organisms living in the sea. - As these organisms died, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. - Over millions of years, due to high pressure, high temperature and absence of air dead organisms were slowly converted into petroleum and natural gas. - These products get trapped between two layers of rocks. - Natural gas always gets collected above petroleum under high pressure. 10. What do you understand by ‘Refining of petroleum’? A. The process of separating the various constituents or fractions of petroleum is known as refining of petroleum. 11. Draw a neat, labelled diagram showing deposits of petroleum and natural gas. A. 12. Write the tips advised to the people by PCRA to save petrol/ diesel while driving. A. - Drive at a constant and moderate speed as far as possible. - Switch off the engine at traffic lights or at a place where you have to wait. - Ensure correct tyre pressure. - Ensure regular maintenance of the vehicle. Std.-VIII/ Science/ Ch-3/ Notes/ 2024-25 Page 2 of 2