SCIENCE CLASS 8

CHAPTER 5

COAL AND PETROLEUM

EXERCISES

Question no. 1

What are the advantages of using CNG and LPG as fuels?

Answer no. 1

There are so many advantages of using CNG and LPG as fuel

1. CNG and LPG are clean fuels and they do not release smoke, hence reduce the pollution.

2. CNG and LPG can be transported easily through pipelines.

3. CNG and LPG burn easily.

4. CNG and LPG gives a lot of heat energy when burnt.

Question no. 2

Name the petroleum product used for surfacing of roads.

Answer no. 2

Bitumen is used for surfacing of roads.

Question no. 3

Describe how coal is formed from dead vegetation. What is this process called?

Answer no. 3

The earth had dense forests in low lying wetland areas. Due to natural processes, such as flooding, these forest got buried under the soil. More and more soil got deposited over them and and they got compressed more. The temperature also rose as they went deeper and deeper. Under high pressure and high temperature, dead plants got slowly converted to coal.

            The process of conversion of dead vegetation into coal is called carbonisation.

Question no. 4

Fill in the blanks:

(a) Fossil fuels are ___________, __________ and ___________.

(b) Process of separation of different constituents from petroleum is called __________.

(c) Least polluting fuel for vehicle is ___________.

Answer no. 4

(a)coal, petroleum, natural gas

(b)refining

(c)compressed natural gas (CNG)

Question no. 5

Tick True/False against the following statements:

(a) Fossil fuels can be made in the laboratory. (T/F)

(b) CNG is more polluting fuel than petrol. (T/F)

(c) Coke is almost pure form of carbon. (T/F)

(d) Coal tar is a mixture of various substances. (T/F)

(e) Kerosene is not a fossil fuel. (T/F)

Answer no. 5

(a)False

(b)False

(c)True

(d)True

(e)False

Question no. 6

Explain why fossil fuels are exhaustible natural resources.

Answer no. 6

The process of formation of fossil fuels requires millions of years. Dead vegetation get buried deep inside the earth and requires high pressure and temperature to get converted into fossil fuel. It cannot be manufactured in factory or laboratory so it is limited in nature. Hence the use of fossil fuels rapid rate will lead to then exhaustion.

Question no. 7

Describe characteristics and uses of coke.

Answer no. 7

Characteristics of coke

1. It is tough

2. It is is porous

3. It is black in colour

4. It is an almost pure form of carbon

Uses

1. It is used in the manufacturing of steel

2. It is used in the extraction of metals

    (As a reducing agent)

Question no. 8

Explain the process of formation of petroleum.

Answer no. 8

Petroleum was formed from organism living in the sea. As these organisms die, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. Over the million of years due to absence of air, high temperature and high pressure dead organism are transformed into petroleum and natural gas.

Question no. 9

The following Table shows the total power shortage in India from 1991– 1997. Show the

data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the

year on the X-axis.

Answer 

ALSO SEE SOLUTIONS OF FOLLOWING CHAPTERS :

Crop Production And Management
Microorganisms - Friend And Foe
Synthetic Fibre And Plastic

Material : Metals And Non - Metals

Coal And Petroleum

SCIENCE CLASS 8

CHAPTER - 4

MATERIALS : METALS AND NON METALS

EXERCISES

Question no. 1

Which of the following can be beaten into thin sheets?

a-  Zinc                 b-  Phosphorus               c-  Sulphur          d-  Oxygen

Answer no. 1

a-  Zinc

Question no. 2

Which of the following statement is correct ?

a-  All metals are ductile

b-  All non metals are ductile

c-  Generally, metals are ductile

d-  Some non metals are ductile

Answer no. 2

c- Generally, metals are ductile

Question no. 3

Fill in the blanks

a-  Phosphorus is a very _________________ non metal.

b-  Metals are _________________ conductors of heat and __________________ .

c-  Iron is ___________________ reactive than copper

d-  Metal react with acid to produce ___________________ gas

Answer no. 3

a-  reactive

b-  good, electricity

c-  more

d-  hydrogen

Question no. 4

Mark  T if the statement is true and  F  if it is false.

a-  Generally, non metals react with acid

b-  Sodium is very reactive metal

c-  Copper displaces zinc from zinc sulphate solution

d-  Coal can be drawn into wires

Answer no. 4

a-  False

b-  True

c-  False

d-  False

Question no. 5

Some properties are listed in the following table. Distinguish between metals and non metals on the basis of these properties.

1. Appearance
2. Hardness
3. Malleability
4. Ductility
5. Heat Conduction
6. Conduction of Electricity

Answer no. 5

Properties                   Metals                   Non -metals

Appearance                 lustrous                 non -lustrous

Hardness                      hard                       soft

Malleability                 malleable              non -malleable

Ductility                       ductile                    not ductile             

 Heat conductors      good conductors     bad conductors

Conductor of            good conductors     bad conductors

   electricity                 of electricity             of electricity

Question no. 6

Give reasons for the following.
a-  Aluminium foils are used to wrap food items.
b-  Immersion rods for heating liquids are made up of metallic substances.
c-  Copper cannot displace zinc from its salt solutions.
d-  Sodium and potassium are stored in kerosene.

Answer no. 6

a-  Aluminium foil are used to wrap food items because it is soft malleable metal it can be beaten to thin sheets which is used in wrapping. Advantage of Aluminium foil is it does not reacts with food items.

b-  Immersion rods are made of metallic substances, because metals are good conductors of heat and electricity. They get hot very soon when electric current is passed through them and thus warm the water.

c-  Copper cannot displace zinc from its salt solution because copper is less reactive then zinc. A less reactive metal cannot displace to more reactive metal from its solution.

d-  Sodium and potassium are very reactive. They reacts vigorously with oxygen and water. A lot of heat is generated in the reaction. Hence they are stored in kerosene.

Question no. 7

Can you store lemon pickle in an aluminium utensil ? Explain

Answer no. 7

Pickle contains of acid which reacts with aluminium to produce salt and hydrogen. Therefore pickle is not stored in aluminium utensil.

Question no. 8

Match the substance given in Column A with their uses given in Column B.

         A                                     B
i-   Gold                        a- Thermometers
ii-  Iron                        b- Electric wire
iii- Aluminium           c- Wrapping food
iv- Carbon                   d- Jewellery
v-  Copper                    e- Machinery
vi- Mercury                 f- Fuel                             

Answer no. 8

(i)   - (d)
(ii)  - (e)
(iii) - (c)
(iv) - (f)
(v)  -  (b)
(iv) - (a)

Question no. 9

What happen when
a-  Dilute sulphuric acid is poured on a copper plate ?
b-  Iron nails are placed in copper sulphate solution ?
      Write word equations of the reactions involved.

Answer no. 9

a-  No reaction occurs when dilute sulphuric acid is poured on a copper plate.
b-  When iron nails are placed in copper sulphate. Iron being more reactive displace copper from copper sulphate. There is a decomposition of copper on the iron nail.
    Fe    +    Cuso4              =         FeSo4             +     Cu
  Iron + Copper sulphate   =  Iron sulphate + Copper

Question no. 10

Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.
a- How will she find the nature of the gas?
b- Write down word equations of all the reactions taking place in this process.

Answer no. 10

a-  Add a few drops of water in the test tube. Now cover the test tube and shake well. After shaking test the solution with blue litmus. If it will change from blue to red colour, so it indicate that gas is acidic in nature.

b-  Charcoal reacts with oxygen to form carbon dioxdi gas
        C    +     O2                            =             CO2
Carbon from + Oxygen   =      Carbondioxide
charcoal

Question no. 11

One day Reeta went to a jeweller’s shop with her mother. Her mother gave old gold jewellery to the goldsmith to polish. Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight?

Answer no. 11

To polish the gold ornament, it is dipped into a liquid aqua regia which is a mixture of hydrochloric acid and nitric acid. On getting dissolved in the aqua regia, the outer layer of gold dissolve in liquid and a shiny layer appears. The dissolving of the layer causes a reduction in the weight of the jewellery.

ALSO SEE SOLUTIONS OF FOLLOWING CHAPTERS :

Crop Production And Management
Microorganisms - Friend And Foe
Synthetic Fibre And Plastic

Material : Metals And Non - Metals

Coal And Petroleum

SCIENCE CLASS 8

SYNTHETIC FIBRES AND PLASTICS

EXERCISES

Question number 1

Explain why some fibres are called synthetic.

Answer number 1

Some fibres are called synthetic fibres because these are man made fibres prepared by using chemical substances. Synthetic fibres are nylon, rayon, acrylic, polyester etc.

Question number 2

Mark (√) the correct answer:
Rayon is different from synthetic fibres because
(a) it has a silk like appearance
(b) it is obtained from wood pulp

(c) its fibres can also be woven like those of natural fibres

Answer number 2

(b) it is obtained from wood pulp.

Question number 3

Fill in the blanks with appropriate words:
(a) Synthetic fibres are also called ______ or _______ fibres.
(b) Synthetic fibres are synthesised from raw material called ________.
(c) Like synthetic fibres, plastic is also a __________ .

Answer number  3

(a) artificial, manmade
(b) petrochemicals
(c) polymer

Question number 4

Give examples which indicate that nylon fibres are very strong.

Answer number 4

1. Parachutes and ropes of rock climbing are made of nylon because of its strongness.
2. Nylon is used in making accessories like rackets.
3.Nylon is used in making scat belt, fishing nets and tyre card.

Question number 5

Explain why plastic containers are favoured for storing food.

Answer number 5

Plastic containers  are used for storing food because it is non - reactive and does not react with the ingredients of food items.

Question number 6

Explain the difference between the thermoplastic and thermosetting plastics.

Answer number  6

Thermosetting plastic

1.Thermosetting plastic cannot be bent.
2.On heating thermosetting plastic, it cannot be softened. because of this it cannot be reshaped.

Thermoplastic

1.Thermoplastic can be bent easily.
2.On heating the thermoplastic, it become softened and can be molded and reshaped easily.

Question number 7

Explain why the following are made of thermosetting plastics.
(a) Saucepan handles
(b) Electric plugs/switches/plug boards

Answer number 7

(a) Thermosetting plastic are bad conductor of heat because of having these property saucepan handles are made of thermosetting plastic and on heating these plastic do not get softened.

(b) Thermosetting plastic are bad conductor of heat and electricity. Because of having these property it is used for making electric plugs, switches, plugs boards etc.

Question number 8

Categorise the materials of the following products into ‘can be recycled’ and ‘cannot be
recycled’:
Telephone instruments, plastic toys, cooker handles, carry bags, ball point pens, plastic
bowls, plastic covering on electrical wires, plastic chairs and electrical switches.

Answer number 8

Can be recycled          Cannot be recycled
1.Plastic chair             1.Cooker handles
2.Plastic bowl             2.Electrical switches
3.Plastic toys               3.Telephone
4.The plastic covering
on electrical wires
5.Carry bags
6.Ballpoint pens

Question number 9

Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from
synthetic material? Advise Rana, giving your reason.

Answer number 9

Rana should buy a cotton shirt for the summer because cotton is a good absorber of water so it can soak the sweat coming out of the body and expose it to the environment and it evaporate. Thus it helps in cooling our body. Synthetic materials are not having this property.

Question number 10

Give examples to show that plastics are non corrosive in nature.

Answer number 10

Plastic do not reacts with water, air. They are not corroded easily even if they come in contact with strong chemicals. For example, the cleaning chemical are stored in plastic bottles, instead of the metal container.

Question number 11

Should the handle and bristles of a tooth brush be made of the same material? Explain
your answer.

Answer number 11

The handle and bristles of a toothbrush should not be made of the same material as the handle of the toothbrush should be strong to hold. The bristles should be soft and flexible because its gives friction to gum while cleaning the teeth.

Question number 12

‘Avoid plastics as far as possible’. Comment on this advice.

Answer number 12

We should avoid plastics as far as possible because plastic are non biodegradable in nature. Once comes into the environment they cause pollution. They can't be destroyed and remains in nature forever. If burnt they release poisonous gases.
 Because of the demerits of plastic, it should be avoid as far as possible.

Question number 13

Match the terms of column I correctly with the phrases given in column II.
Column I                 Column II
(i) Polyester     (a) Prepared by using
                           wood pulp
(ii) Teflon         (b) Used for making
                           parachutes and stockings
(iii) Rayon        (c) Used to make non-stick
                          cookwares
(iv) Nylon        (d) Fabrics do not wrinkle easily

Answer number 13

Match the terms of column I correctly with the phrases given in column II.
Column I                Column II
(i) Polyester      (d) Fabrics do not wrinkle
                            easily
(ii) Teflon          (c) Used to make non-stick
                            cookwares
(iii) Rayon         (a) Prepared by using
                            wood pulp
(iv) Nylon          (b) Used for making
                            parachutes and stockings

Question number 14

‘Manufacturing synthetic fibres is actually helping conservation of forests’. Comment.

Answer number 14

The manufacturing of synthetic fibres is helpful in the conservation of forests because for natural fibres raw material is obtained from the plants which required cutting of lots of trees. Hence manufacturing of synthetic fibres helpful in the conservation of forests.

Question number 15

Describe an activity to show that thermoplastic is a poor conductor of electricity.

Answer number 15

In order to prove that thermoplastic is a poor conductors of electricity the under mention experiment is to be done. For the experiment one piece of plastic material is to be taken and its both end should be connected to a battery and bulb per the diagram. When current pass through the circuit the bulb does not glow it prove that thermoplastic are poor conductor of electricity.

ALSO SEE SOLUTIONS OF FOLLOWING CHAPTERS :

Crop Production And Management
Microorganisms - Friend And Foe
Synthetic Fibre And Plastic

Material : Metals And Non - Metals

Coal And Petroleum

SCIENCE CLASS-8 

CHAPTER -2 

MICROORGANISMS - FRIEND AND FOE 

EXERCISES

Question number 1

Fill in the blanks.

(a) Microorganisms cam be seen with the help of a __________________.

(b) Blue green algae fix ________________ directly from the air to enhance fertility of soil.

(c) Alcohol is produced with the help of ________________.

(d) Cholera is caused by __________________.

Answer number 1

(a) microscope.

(b) nitrogen.

(c)yeast.

(d)bacteria.

Question number 2

Tick the correct answer.

(a) Yeast is used in the production of 

(i)sugar

(ii)alcohol

(iii)hydrochloric acid

(iv)oxygen

(b) The following is an antibiotic

(i)sodium bicarbonate

(ii)streptomycin

(iii)alcohol

(iv)yeast

(c) Carrier if malaria - causing protozoan is

(i)female anopheles mosquito

(ii)cockroach

(iii)housefly

(iv)butterfly

(d) The most common carrier of communicable diseases is

(i)ant

(ii)housefly

(iii)dragonfly

(iv)spider

(e) The bread or Idli dough rises because of

(i)heat

(ii)grinding

(iii)growth of yeast cell

(iv)kneading

(f) The process of conversion of sugar into alcohol is called

(i)nitrogen fixation

(ii)moulding

(iii)fermentation

(iv)infection

Answer number 2

(a) alcohol

(b) streptomycin

(c) female anopheles mosquito

(d) housefly

(e) growth of yeast cell

(f) fermentation

Question number 3

Match the organism in Column A with their action in Column B

             A                                       B

(i)Bacteria                       (a)fixing nitrogen

(ii)Rhizobium                 (b)setting of curd

(iii)Lactobacillus           (c)baking of bread

(iv)Yeast                          (d)causing malaria

(v)A protozoan              (e)causing cholera

(vi)A virus                       (f)causing AIDS

                                          (g)producing antibodies

Answer number 3

          A                                B

(i)Bacteria                   (e)Causing cholera

(ii)Rhizobium             (a)Fixing nitrogen

(iii)Lactobacillus        (b)Setting of curd

(iv)Yeast                       (c)Baking of bread

(v)A protozoan           (d)Causing malaria

(vi)A virus                   (f)Causing AIDS

Question number 4

Can microorganisms be seen with the naked eyes? If not, how can they be seen

Answer number 4

Microorganisms can not be seen by naked eyes, because they are very small. They can be seen with the help of microscope.

Question number 5

What are the major groups of microorganisms?

Answer number 5

Major groups of microorganisms are as follow -

• Bacteria
• Fungi
• Protozoa
• Algae
• Viruses

Question number 6

Name the microorganism which can fix atmospheric nitrogen in the soil.

Answer number 6

The name of microorganism which can fix atmospheric nitrogen in the soil is Rhizobium.

Question number 7

Write 10 lines on the usefulness of microorganisms in our lives.

Answer number 7

1. They are helpful in cleaning up of the environment. The organic waste (vegetable peels, remains of animals, faeces etc. ) are broken down into harmless and useful substances by bacteria.
2. In agriculture they are used to increase the soil fertility by fixing nitrogen.
3. They are used in the preparation of medicines.
4. Microorganisms are useful in making curd and bread. Lactobacillus promotes the formation of curd. It multiplies in the milk and converts it into curd.
5. Bacteria are involved in the making cheese, pickle and many other food items.
6. Microorganisms are used for the large scale production of alcohol, wine and acetic acid (vinegar)
7. Antibiotics are being produced by bacteria  and fungi.
8. Microorganisms are helpful in producing vaccines which protect from several diseases such as cholera, tuberculosis, small pox and hepatitis.
9. Some bacteria and blue green algae are able to fix nitrogen from the atmosphere to enrich soil with nitrogen and increase its fertility.
10. Microorganisms helps in cleaning the environment by decomposing dead organic waste of plants and animals to convert them into simple substances.

Question number 8

Write a short paragraph on the harms caused by microorganisms.

Answer number 8

Microorganisms are harmful in many ways. Microorganisms causes diseases in human beings, plants and animals such microorganisms are called pathogens. Pathogens enters our body through air we breathe, the water we drink or the food we eat. They can spread communicable diseases such as cholera, common cold, chicken pox and tuberculosis.

               Microorganisms spoil food by decomposing the food material. They spoil leather and clothes also. They are also responsible for food poising.

Question number 9

What are antibiotics? What precautions must be taken while taking antibiotics?

Answer number 9

Antibiotics hill or stop the growth of the disease causing microorganisms.

Antibiotics should be taken only on the advice of a qualified doctor. Also antibiotic course must be completed prescribed by the doctor. Antibiotics should not be taken unnecessarily because it may hill the beneficial bacteria present in our body.

ALSO SEE SOLUTIONS OF FOLLOWING CHAPTERS :

Crop Production And Management
Microorganisms - Friend And Foe
Synthetic Fibre And Plastic

Material : Metals And Non - Metals

Coal And Petroleum

CLASS 8 SCIENCE

CROP PRODUCTION AND MANAGEMENT

EXERCISES

QUESTION NO. 1

1. Select the correct word from the following list and fill in the blanks.

    float, water, crop, nutrients, preparation

(a) The same kind of plant grown and cultivated on a large scale at a place is called _____________

(b) The first step before growing crops is ____________ of soil.

(c) Damaged seeds would ___________ on the to of water.

(d) For growing a crop, sufficient sunlight and _____________ and ______________ from the soil essential.

ANSWER NO. 1

(a) crop

(b) preparation

(c) float

(d) water, nutrients

QUESTION NO. 2

2. Match items in column A with those in column B

                 A                                             B

(i)Kharif crops                      (a)Food for cattle

(ii)Rabi crops                        (b)Urea and super phosphate

(iii)Chemical fertilisers     (c) Animal excreta, cow dung

                                                 urine and plant waste

(iv)Organic manure            (d)Wheat, gram, pea

                                                 (e)Paddy and maize

ANSWER NO. 2

(i)Kharif crops                  -  (e)Paddy and maize

(ii)Rabi crops                     -  (d)Wheat, gram, pea

(iii)Chemical fertilisers  -  (b)Urea and super

                                                   phosphate

(iv)Organic manure        -  (c)Animal excreta,

                                               cow dung, urine 

                                                and plant waste

QUESTION NO. 3

3. Give two examples of each.

(a) Kharif crop

(b) Rabi crop

ANSWER NO. 3

(a) Kharif crop - Paddy and maize

(b) Rabi crop - Wheat and gram

QUESTION NO. 4

4. Write a paragraph in your own words on each of the following.

(a)  Preparation of soil               (b)  Sowing

(c)  Weeding                                 (d)  Threshing

ANSWER NO. 4

(a) Preparation of soil :-  The preparation of soil is the first and important step before growing a crop. In this process the soil is to turn and loosen. It is necessary for the root penetration into the soil.
The loosen soil allows the roots to breathe easily while they go deep into the soil. Further the loosened soil helps in the growth of earthworms and microbes present in the soil. These organisms further turn and loosen the soil and add humus to it.

(b) Sowing :-  Sowing is the most important part of crop production. Good quality seeds are selected for sowing. Good quality seeds are clean and healthy seeds of a good variety chosen. Sowing is done by ether traditional methods or by using equipments seed drill.

(c) Weeding :-  The removal of undesirable plants which are grown along with the crop is called weeding. Weeding is important because weeds compete with the crop plants for water, nutrients, space and light. Hence they affect the growth of the crop. Some type of weeds interfere even in harvesting and may be poisonous for animals and human beings.

(d) Threshing :-  Threshing is a process in which chaff is separated from the crop. It is done by a machine which is called combine in. It is a combination of harvester and thresher.
                   Separation of grain and chaff is also done by winnowing in which blow of wind is used.

QUESTION NO. 5

5. Explain how fertilisers are different from manure.

ANSWER NO. 5

There are so many difference between fertilisers and manure which are as follows.

                        Fertilisers

.A fertilisers is an inorganic salt.
.Fertilisers are prepared in factories.
.A fertiliser does not provide any humus to soil.
.Fertilisers are very rich in plant nutrients such as
nitrogen, potassium and phosphorus. 

                       Manure

.Manure is a natural substance obtained by the 

decomposition of cattle dung, plant residues and

human waste.

.Manure can be prepared in the fields.

.Manure provides a lot of humus to the soil.

.Manure is comparatively less rich in plant nutrients.

QUESTION NO. 6

6.What is irrigation? Describe two methods of irrigation which conserve water.

ANSWER NO. 6

Irrigation 

The supply of water to crops at different intervals is called irrigation. The interval of irrigation depends upon type of crop, soil and season.

                    The conserving method of irrigation are :

(a) Drip Irrigation

In this method, the water falls drop by drop at the position of the roots. Because of water drop at roots only it is called drip method. In this method water provides to drop by drop hence water is not wasted at all. It is a boon in regions where there is  scarcity of water.

 (b) Sprinkling Method

This system is useful on the uneven land where sufficient water is not available. In this system perpendicular pipes having rotating nozzles on top, are joined to the main pipeline at regular intervals. When water is allowed to flow through the main pipe under pressure with the help of a pump, water flows forcefully from the rotating nozzles. It gets sprinkled on the crop resembling like raining. This method is very useful for sandy soil.

QUESTION NO. 7

If wheat is sown in the kharif season, what would happen? Discuss

ANSWER NO. 7

Kharif season normally covers June to October. If in this season wheat is sown, then there is a chance that wheat crop will be destroyed. The factors of destroying the crops will be lack of favourable temperature, adaptability of crop in this season and availability of pests etc. Kharif season covers the rainy season, which is not suitable for the wheat crop. Hence wheat crop should not be sown during kharif season.

QUESTION NO. 8

Explain how soil get affected by the continuous plantation of crop in a field

ANSWER NO. 8

Due to continuous plantation of crop in a field soil becomes poor in certain nutrients such as nitrogen, phosphorus, potassium etc. When a farmer continues to grow crops one after the others, then the nutrients available in the soil are continuously utilised by the crops and the production of crops decreases automatically.

QUESTION NO. 9

What are weeds? How can we control them?

ANSWER NO. 9

Weeds are unwanted plants which grows with the crops. these weeds utilise the soil nutrients hence the optimum required of nutrients from crops is not fulfilled. Hence weeds are very harmful. Weeds re controlled by following methods.

• Tilling before sowing of crop.

• By using of weedicides.

• Manual removing of weeds with khurpi.

QUESTION NO. 10

Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.

Sending crop to           Irrigation           Sowing

sugar factory

Harvesting       Preparation of             Manuring

                                soil   

                   

                         Ploughing the field

ANSWER NO. 10

1. Preparation of soil.
2. Ploughing the field.
3. Sowing.
4. Irrigation.
5. Manuring.
6. Harvesting.
7. Sending crop to sugar factory.

QUESTION NO. 11

Complete the following word puzzle with the help of clues given below.

                 Down

Providing water to the crops.

Keeping crop grains for a long time under proper conditions

Certain plants of the same kind grown on a large scale

              Across

A machine used for cutting the mature crop

A rabi crop that is also one of the pulses

A process of separating the grain from chaff

ANSWER NO. 11

         Down

1. Irrigation
2. Storage
3. Crop

         Across

      4. Harvesting

      5. Gram

      6.Winnowing

ALSO SEE SOLUTIONS OF FOLLOWING CHAPTERS :

Crop Production And Management
Microorganisms - Friend And Foe
Synthetic Fibre And Plastic

Material : Metals And Non - Metals

Coal And Petroleum