Something to Know
A. Fill in the blanks.
1. Food acts as fuel for our body.
2. Cowdung cake has been often used as a domestic fuel.
3. Aeroplanes use highly refined kerosene based fuel.
4. CNG is a better green fuel.
5. Petrol and diesel are fossil fuels used for transportation.
6. Solar energy is a renewable source of energy.
B. Write True or False for the following statements.
1. LPG is used as a domestic fuel. True
2. Some train engines run on diesel. True
3. Powerhouses burn CNG to generate electricity. False
4. Coal is a renewable source of energy. False
5. We should use public transport to help reduce environmental pollution. True
C. Tick (✔) the correct option.
1. Out of the following, the fuel, that is best for reducing environmental pollution, is-
(a) diesel
(b) coal
(c) compressed natural gas (✔)
(d) cowdung cakes
Answer – (c) compressed natural gas (✔)
2. A good fuel is one that-
(a) does not burn easily.
(b) is costly and not easily available.
(c) does not produce smoke or leave ash. (✔)
(d) is not easy to store.
Answer – (c) does not produce smoke or leave ash. (✔)
3. A fuel, that is not obtained by refining petroleum, is-
(a) petrol
(b) diesel
(c) kerosene
(d) biogas (✔)
Answer – (d) biogas (✔)
4. Out of the following, the energy source, that is a renewable energy source, is-
(a) petrol
(b) wind (✔)
(c) diesel
(d) coal
Answer – (b) wind (✔)
5. Coal, a common fossil fuel, is formed-
(a) from the waste of animals.
(b) from dead sea-creatures.
(c) by decay of water plants.
(d) by decay of vegetation, under heat and high pressure, over a long period of time. (✔)
Answer – (d) by decay of vegetation, under heat and high pressure, over a long period of time. (✔)
D. Answer the following questions in brief.
1. State the main function of a fuel.
Answer – The main function of fuel is to produce energy on burning. This energy can be used for cooking, for movement of vehicles, to generate electricity and for running various machines.
2. Give one example each of solid, liquid and gaseous fuels.
Answer – Solid fuel- Coal
Liquid fuel- Petrol
Gaseous fuel- CNG
3. Why is biogas regarded as a better fuel than cowdung cakes?
Answer – Biogas is regarded as a better fuel than cowdung cakes because it does not produce smoke on burning and does not leave any ash after burning.
4. Why is CNG called a better green fuel?
Answer – CNG is called a better green fuel because it causes less air pollution, is more eco-friendly and causes less harm to the health of humans and animals.
5. Name the three main fossil fuels.
Answer – Three main fossil fuels are coal, crude oil and natural gas.
6. State two disadvantages of fossil fuels.
Answer – Two disadvantages of fossil fuels are:
(i) They are limited in nature.
(ii) They are also a major cause of environmental pollution.
E. Answer the following questions.
1. How have fossil fuels been formed?
Answer – Fossil fuels are formed by decomposition of animal and plant matter, buried under the surface of earth, at the high temperature and pressure prevailing there. Such deep buried animal and plant matter got changed into fossil fuels over a period of millions of years.
2. When is a source of energy said to be a renewable source of energy? Give two examples of such sources.
Answer – A source of energy is said to be a renewable source of energy if it is freely available and can be readily replenished. Examples are solar energy, tidal energy.
3. When is a source of energy said to be a non-renwable source of energy? Give two examples of such sources.
Answer – A source of energy is said to be a non-renewable source of energy if it is once used cannot be readily replenished. Examples are coal and petroleum.
4. How is coal used by powerhouses for generating electricity?
Answer – Powerhouses burn coal to convert water into steam. This steam energy is used to operate turbines which in turn, help to generate electricity.
5. Why should efforts need to be made to reduce the use of fossil fuels?
Answer – Efforts need to be made to reduce the use of fossil fuels because they are available in limited quantity and are not likely to last for a long time.
Value Based Question
Ramesh, a very hardworking and sincere engineer, got a chance to visit a village in a far flung area. The people of the village were using wood and cowdung cakes as the fuel for cooking their food. They also did not keep their village neat and clean.
Ramesh explained to villagers the importance of cleanliness in their life. He also helped them to set up a biogas plant. The villagers felt very happy when they started using this new fuel. They found it to be a convenient, cleaner and more eco-friendly fuel.
1. State the values, and qualities, displayed by Ramesh.
Answer – The values and qualities, displayed by Ramesh are hardworking, sincere, helping, understanding, cleanliness.
2. Why is biogas a better fuel than wood or cowdung cakes?
Answer – Biogas is a better fuel than wood or cow dung cakes because it does not produce smoke on burning and does not leave any ash after burning. It does not cause any health hazards also.
3. Discuss how a neat and clean environment is good for ‘one and all’.
Answer – Neat and clean environment is good for one and all because it prevents spread of diseases and gives positive vibes.
Something to Do
1. Make a poster on: ‘Energy saved today is the energy for tomorrow’.
Answer –
2. Make a presentation on ‘Wind energy and its practical uses’.
Answer – Student will do this at their own.
3. Collect information about the following and discuss it with your classmates and teacher:
(a) What is meant by the ‘mileage’ of a vehicle?
Answer – ‘Mileage’ of a vehicle means that Its how many kilometers the is vehicle going to run per litre of fuel.
(b) Do all vehicles give the same ‘mileage’?
Answer – No
(c) How can one get a better ‘mileage’ from a vehicle like a car?
Answer –
- Keep Engine in a Good Health. One of the best ways to improve car mileage is to take care of your car.
- Reduce the Load Inside the Car.
- Use Correct Engine Oil.
- Be Easy on Pedal.
- Maintain the Right Air Pressure.
- Avoid Over-revving.
- Use Gears Correctly.
- Check Wheel Alignment.
4. Collect information about how solar energy can be used to get electricity. Find out the names of some places where ‘solar power projects’ are being put to use.
Answer – Solar technologies convert sunlight into electrical energy either through photovoltaic (PV) panels or through mirrors that concentrate solar radiation.
Names of some places where ‘solar power projects’ are being put to use
1. Bhadla Solar Park, Rajasthan
2. Pavagada Solar Park
3. Kurnool Ultra Mega Solar Park, Andhra Pradesh
4. NP Kunta Ultra Mega Solar Park
Inside Questions
1. Give some examples of solid, liquid and gaseous fuels.
Ans- Solid fuels- Wood, coal, coke and cowdung cakes.
Liquid fuels- Kerosene, petrol and diesel.
Gaseous fuels- LPG, CNG, PNG, biogas.
2. Where do we use fuels?
Ans- We uses fuels for:
Cooking
For movement of trains, automobiles and aeroplanes.
For generating electricity, for running various machines.
3. List the domestic fuels.
Ans- LPG, PNG and biogas are cleaner fuels. Fuels such as wood, cowdung cakes, coal, kerosene cause pollution.
4. Which fuel is used in aeroplanes?
Ans- Aviation Turbine Fuel(ATF) which is a highly refined kerosene based fuel, is used in aeroplanes.
5. How was petroleum formed?
Ans- Petroleum was formed from dead sea creatures. These dead sea-creatures fell to the sea-bed where their bodies underwent chemical changes due to bacteria.
6. Differentiate between renewable and non-renewable sources of energy.
Ans- Renewable sources of energy are freely available and can be readily replenished. Whereas non-renewable sources of energy once used, cannot be replenished.
Examples of renewable sources are solar energy, tidal energy, wind energy and biomass.
Examples of non-renewable sources of energy are coal, petroleum.
7. How can we save fossil fuels?
Ans- We can save fossil fuels by adopting following measures:
(I) We should walk or use cycle to go the nearby places.
(ii) We should form carpools to go to the same place.
(iii) We should use public transport like buses and metro trains for travelling within the city.
By Sunaina Karmakar