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Q1. Natural gas is formed from fossilized insects.

• 1) True
• 2) False

Solution

False

Q2. (a) What are petrochemicals? (b) Which conditions under the sea formed petroleum? (c) Why natural gas is considered as one of the most important forms of fossil fuel?

Solution

(a) Various useful constituents obtained from petroleum are called petrochemicals i.e. petroleum gas, petrol, diesel, paraffin wax, lubricating oil etc. (b) Absence of air, high temperature and high pressure are the conditions responsible for formation of petroleum under the sea. (c) Natural gas considered one of the most important forms of fossil fuel because it is very easy to transport through pipes and cylinders.

Q3. Which of the following is an example of inexhaustible source of energy?

• 1) All the above
• 2) Wind
• 3) Water
• 4) Sun

Solution

Sun, wind, and water are present in unlimited quantity in nature and are inexhaustible.

Q4. Burning of fossil fuel causes pollution.

• 1) True
• 2) False

Solution

True

Q5. Petroleum is a complex mixture of compounds known as ________.

Solution

Petroleum is a complex mixture of compounds known as hydrocarbons.

Q6. Petroleum is formed from dead

• 1) Sea rocks
• 2) Sea plants
• 3) Sea animals
• 4) Gases

Solution

Petroleum was formed from dead organisms that once lived in the sea.

Q7. (a) What is destructive distillation of coal? (b) What are the various products of coal obtained by destructive distillation of coal? Explain them along with their uses.

Solution

(a) The strong heating of coal in the absence of air is called destructive distillation of coal. (b) The various products obtained by destructive distillation of coal are: coal gas, coal tar and coke. 1. Coal Gas:  Coal gas is a gaseous fuel which is obtained by the strong heating of coal in the absence of air during the processing of coal to get coke. Coal gas is mainly a mixture of methane and hydrogen, with some carbon monoxide. All the gases present in coal gas can burn to produce heat, due to which coal gas is an excellent fuel (having high calorific value). Coal gas is used as a fuel in industries. These days, however, coal gas is used as a source of heat rather than light.  2. Coal Tar: Coal tar is a thick, black liquid having an unpleasant smell which is obtained by heating coal in the absence of air. Coal tar is not a single compound. Coal tar is a mixture of about 200 carbon compounds (or organic compounds). The products of coal tar are used to make synthetic fibres, drugs (medicines), plastics, synthetic dyes, perfumes, paints, varnishes, pesticides, photographic materials, roofing materials and explosives, etc. Coal tar has been traditionally used for metalling the roads. 3. Coke: Coke is a tough and porous black solid substance Coke is prepared by heating coal in the absence of air. Coke is an almost pure form of carbon. Coke is mainly used as a reducing agent in the extraction of metals (like iron, zinc etc.) Coke is used in the manufacture of steel. Coke is also used as a fuel.   

Q8. The slow process by which the dead plants buried deep under the earth have become coal is called ________.

Solution

The slow process by which the dead plants buried deep under the earth have become coal is called carbonisation.

Q9. Which of the following is not a product of destructive distillation of coal?

• 1) Coal tar
• 2) Coke
• 3) Coal gas
• 4) Bitumen

Solution

The products of destructive distillation of coal are coke, coal tar and coal gas.

Q10. Coke is a better fuel than coal.

• 1) True
• 2) False

Solution

True

Q11. Which is not a non-renewable source of energy?

• 1) Crude oil
• 2) Petrol
• 3) Water
• 4) Coal

Solution

Water is a renewable source of energy.

Q12. Petrol, LPG, CNG, diesel are products obtained from petroleum refinery.

• 1) True
• 2) False

Solution

False

Q13. Coal comes from dead plant matter falling into the dry open land.

• 1) False
• 2) True

Solution

False

Q14. List two advantages of using CNG as fuel.

Solution

Advantages of using CNG: 1. It is a clean fuel and does not cause much pollution. 2. It can be directly supplied to home and industry through pipeline.

Q15. _______ is also known as black gold.

Solution

Petroleum is also known as black gold.

Q16. How is fossil fuel linked to global warming?

Solution

The burning of fossil fuels produces carbon dioxide gas as the main by-product which causes green house effect. This leads to global warming.

Q17. Kerosene is an inexhaustible energy resource.

• 1) True
• 2) False

Solution

False

Q18. Coke is very important for iron and steel industry.

• 1) True
• 2) False

Solution

True

Q19. Fossil fuels will provide energy for a limited period of time, as they will eventually be depleted.

• 1) True
• 2) False

Solution

True

Q20. The slow conversion of dead vegetation into coal is called carbonisation.

• 1) False
• 2) True

Solution

True

Q21. Petroleum on burning produces mainly _______ gas.

Solution

Petroleum on burning produces mainly carbon dioxide gas.

Q22. Coal is a combustible material.

• 1) False
• 2) True

Solution

True

Q23. The liquid product obtained on processing coal is ______.

Solution

The liquid product obtained on processing coal is coal tar.

Q24. Man is trying to use other energy sources in place of coal. Give two reasons.

Solution

a. Coal is exhaustible natural resource of energy. b. When coal is burnt, it causes air, water and land pollution.

Q25. What is the main constituent of coal gas?

• 1) Oxygen
• 2) Methane
• 3) Nitrogen
• 4) Carbon

Solution

Coal gas is mainly methane.

Q26. (a) Which petroleum product is used for metalling the roads in place of coal-tar? Give its one use. (b) Which petroleum product is used in ointments and in candles? Give its one use. (c) Which petroleum product is used as domestic fuel? Give its one use.

Solution

(a) Bitumen is used for metalling the roads in place of coal-tar. It is also used in paints. (b) Paraffin wax is used in ointments and in candles. It is also used in Vaselines. (c) Liquefied petroleum gas (L.P.G) is used as domestic fuel. It is also used as fuel in vehicles and industry.

Q27. Which of the following is not a fossil fuel?

• 1) Sunlight
• 2) Petroleum
• 3) Natural gas
• 4) Coal

Solution

Coal, petroleum and natural gas are fossil fuels.

Q28. CNG stands for

• 1) Compressed natural gas
• 2) Compressed non gas
• 3) Combustible natural gas
• 4) Combustible non gas

Solution

CNG stands for Compressed natural gas.

Q29. Materials taken from earth for use are termed _______ resources.

Solution

Materials taken from earth for use are termed natural resources.

Q30. A substance that is black hard stone which is formed by dead remains of the living organisms and is mainly used as fossil fuel. Identify that substance and write its uses.

Solution

Coal is that fossil fuel which is as hard as a stone and is black in colour. Uses: (i) It is used as fuel to cook food. (ii) It is used to run trains, as it is burnt to generate steam in engine.

Q31. Coal tar is used in the manufacture of steel.

• 1) True
• 2) False

Solution

False

Q32. Coal and its products are exhaustible natural energy resource.

• 1) True
• 2) False

Solution

True

Q33. Justify the statement: Coal is formed by carbonisation.

Solution

Carbonisation is the conversion of organic matter to carbon containing product. Coal mainly contains carbon. Therefore, the conversion of dead vegetation into coal is called carbonisation.

Q34. Fossil fuels are everlasting.

• 1) False
• 2) True

Solution

False

Q35. Diesel is used in heavy motor vehicles and electric generators.

• 1) True
• 2) False

Solution

True

Q36. A substance is black liquid obtained during destructive distillation of coal. It is thick and smells unpleasant. It is a mixture of hundreds of substances. Identify the substance. How it is useful to us?

Solution

Black liquid obtained during destructive distillation of coal is coal-tar. It is thick and smells unpleasant. It is a mixture of hundreds of substances. (i) Substances obtained from coal-tar are used to manufacture synthetic dyes, drugs, explosives, perfumes, plastics, paints, photographic materials etc. (ii) Earlier, it was also used for surfacing of roads.

Q37. (a) Which product of coal is used in anti-dandruff shampoos.State its any other use. (b) How is it obtained?

Solution

(a) Coal tar is used in anti-dandruff shampoos.It is used in metalling of roads. (b) It is obtained as a by-product of the process of manufacturing coke.

Q38. This is map of India, write 2 places where natural gas is found?

Solution

The places where natural gas is found are: 1. Tripura 2. Rajasthan 3. Maharashtra 4. Krishna Godavari delta

Q39. How is natural gas formed?

Solution

Natural gas was formed from the remains of dead sea organisms buried deep below the Earth's surface by layers of sediment (sand, mud, clay etc.). Over long periods of time, the dead organisms were transformed by heat and pressure into natural gas.

Q40. Why is petroleum sometimes called 'black gold'?

Solution

Petroleum is sometimes called 'black gold' because of its great commercial importance and uses.