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Lessons
- Crop Production & Management
- Microorganisms – Friends & Foe
- Synthetic, Fibers & Plastic
- Materials – Metals and Non Metals
- Combustion and Flame
- Conservation Of Plants And Animals
- Coal & Petroleum
- Cell Structure And Functions
- Reproduction In Animals
- Reaching The Age Of Adolescence
- Force And Pressure
- Friction
- Sound
- Chemical Effects Of Electric Current
- Some Natural Phenomena
- Light
- Stars And The Solar System
- Pollution Of Air And Water
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Question Bank
- Question Bank – Chapter 1 – Crop Production & Management
- Question Bank – Chapter 2 – Microorganisms
- Question Bank – Chapter 3 – Synthetic Fibres and Plastics
- Question Bank – Chapter 4 – Metals and Non Metals
- Question Bank – Chapter 5 – Coal & Petroleum
- Question Bank – Chapter 6 – Combustion and Flame
- Question Bank – Chapter 7 – Conservation of Plants and Animals
- Question Bank – Chapter 8 – Cell Structure & Functions
- Question Bank – Chapter 9 – Reproduction
- Question Bank – Chapter 10 – Reaching the age of adolescence
- Question Bank – Chapter 11 – Force and Pressure
- Question Bank – Chapter 12 – Friction
- Question Bank – Chapter 13 – Sound
- Question Bank – Chapter 14 – Chemical Effects of Electric Current
- Question Bank – Chapter 15 – Some Natural Phenomena
- Question Bank – Chapter 16 – Light
- Question Bank – Chapter 17 – Stars and Solar System
- Question Bank – Chapter 18 – Pollution of Air & Water
Coal & Petroleum
• We use various materials for our basic needs. Some of them are found in nature and some have been made by human efforts.
• Air, water, soil and minerals are obtained from nature and are called natural resources.
• We cannot use all our natural resources forever.
• Water a limited resource.
• Inexhaustible Natural Resource present in unlimited quantity in nature and are not likely to be exhausted by human activities.
• Sunlight, air are inexhaustible natural resources.
• Exhaustible Natural Resources are limited in nature and can be exhausted by human activities.
• Examples of Exhaustible Natural Resources are forests, wildlife, minerals, coal, petroleum, natural gas etc.
• Exhaustible natural resources like coal, petroleum and natural gas are formed from the dead remains of living organisms.
• Coal is as hard as stone and is black in colour.
• Coal is one of the fuels used to cook food.
• As coal contains mainly carbon, the slow process of conversion of dead vegetation into coal is called carbonisation.
• Coal is also formed from the remains of vegetation therefore it is also called a fossil fuel.
• When heated in air, coal burns and produces mainly carbon dioxide gas.
• Coal is processed in industry to get some useful products such as coke, coal tar and coal gas.
• Coke is a tough, porous and black substance. It is almost pure form of carbon. Coke is used in the manufacture of steel and in the extraction of many metals.
• Coal tar is a black, thick liquid with unpleasant smell. It is a mixture of about 200 substances.
• Products obtained from coal tar are used in everyday life and in industry, like synthetic dyes, drugs, explosives and perfumes.
• Nowadays, bitumen, a petroleum product, is used in place of coal-tar for metalling the roads.
• Coal gas was used for street lighting for the first time in London in 1810 and in New York around 1820. Nowadays, it is used as a source of heat rather than light.
• Petrol and diesel are obtained from a natural resource called petroleum.
• Over millions of years, absence of air, high temperature and high pressure transformed the dead organisms into petroleum and natural gas.
• The world’s first oil well was drilled in Pennsylvania, USA, in 1859. Eight years later, in 1867, oil was stuck at Makum in Assam.
• In India, oil is found in Assam, Gujarat, Mumbai High and in the river basins of Godavari and Krishna.
• 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.
• Many useful substances are obtained from petroleum and natural gas. These are termed as ‘Petrochemicals’.
• Hydrogen gas obtained from natural gas, is used in the production of fertilizers.
• Petroleum gas, petrol, diesel, kerosene, paraffin wax, lubricating oil are obtained by refining petroleum.
• Due to its great commercial importance, petroleum is also called ‘black gold’
• Natural gas is stored under high pressure as compressed natural gas (CNG).
• CNG is used for power generation. It is now being used as a fuel for transport vehicles because it is less polluting. It is a cleaner fuel.
• Natural gas is also used as a starting material for the manufacture of a number of chemicals and fertilizers.
• In India, natural gas has been found in Tripura, Rajasthan, Maharashtra and in the Krishna Godavari delta.
• Coal and petroleum are fossil fuels.
• Burning of coal and petroleum is a major cause of air pollution.
• Coal and petroleum resources are limited. We should use them judiciously