What is coal and how was it formed ? Explain.


Coal is a fossil fuel which is as hard as a stone. It is black in colour and is mainly used as fuel.

As coal is a fossil fuel, it was formed by the dead remains of the plants. Millions of years ago vegetation in forests got trapped under soil layers due to earthquakes and volcanic eruptions. More soil layers got deposited on it and it went deeper and deeper beneath the earth. This raised the temperature and pressure beneath the soil. This initiated the process of burning these dead remains. Slowly all the vegetations got converted into coal which is a rich form of carbon. This whole process is also called carbonization.

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Classify various materials we use in our lives.


All the materials we use can be broadly classified into two groups :

(a) Natural Resources, (b) Man-made Resources.

(a) Natural resources are those resources which are present in our nature, gifted by God. They can be freely used. Soil, air, sunlight, water, wildlife, etc. are some natural resources.

(b) Man-made resources are those resources which are formed by various efforts of man and are artificial. Plastics, fibres, electricity, etc. are all artificial resources.

On availability of materials natural materials can further be classified as :

(i) Inexhaustible Natural Resources : Those resources which are present in unlimited quantity and will never get exhausted by human activities. Sunlight, air, soil, etc. are some inexhaustible natural resources.

(ii) Exhaustible Natural Resources :

Those resources which are available in limited amount and will get finished by human activities. Petroleum, coal, wildlife, forests, etc. are some examples of exhaustible natural resources.


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How was petroleum formed ? What is refining of petroleum ?


Petroleum is a fossil fuel which got formed by the dead remains of the sea animals. These animals slowly got trapped under soil and clay and more deposits were formed with time. Due to depth, the temperature and pressure raised and over the years they got converted into petroleum oil. Since oil is lighter than water, it did not get mix with water and got raised to the superficial rocks, which did not allow it to pass through them. To obtain petroleum, we have to dig wells to perforate the top rocks and pump up the petroleum oil.

The petroleum oil we get from these wells is a mixture of various other useful substances. Petroleum oil is, thus, refined to separate these useful by-products in petroleum refineries.




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What is destructive distillation of coal ? Describe the constituents obtained from this process.


Burning of coal in absence of air to obtain some useful constituents is called destructive Distillation. Following constituents are obtained from this process :

(i) Coke : It is a hard porous substance which is almost the purest form of carbon. It is used in manufacture of steel and in extraction of many metals.

(ii) Coal-tar : It is a black liquid with unpleasant smell. It is a mixture of about two hundred substanes which are very useful in our day to day life. They are used in drugs, plastics, paints, photographic materials, synthetic dyes, roofing materials, perfumes, explosives etc. Insect repellants like naphthalene is also obtained from it. Earlier, it was also used for surfacing of roads.

(iii) Coal gas : This gas is also obtained during destructive distillation of coal. It is used as fuel in coal processing plants and in various other industrial units situated near coal processing plants. Coal gas was used by the Americans and the Britishers for street lighting.

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Write some ways in which we can conserve fossil fuels.


Economic and controlled consumption of fossil fuel can help conserving our natural resources. Following ways and measures can conserve our resources:

(i) Vehicles should be driven at constant and moderate speed.

(ii) Engines should be switched off at traffic lights or other temporary halts.

(iii) Proper and regular maintenance of vehicles.

(iv) Vehicle pooling can reduce number of vehicles plying on road thus less consumption of fuel.

(v) At home gas stoves should be cleaned properly and burners should not be left burning unnecessarily.

(vi) Pressure cookers should be preferred to pans. If pans are being used, they should be properly covered and their bottoms should not have deposits of burnt oil.

(vii) Small pans and burners should be used and pulses etc. should be dipped in water before cooking them.

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