CLASS – VI ( chemistry)
LESSON 3( Plant fibres and fabrics)
Q1. What is fibre ?
Ans. A fibre is a kind of thread used to make clothes .
Q2. Name two items that are made from cotton fibre.
Ans. Clothes and bandages.
Q3. What is retting?
Ans. Retting is the process used for obtaining plant fibre from the stems of the plant by keeping them in stagnant water for a few days.
Q4. Give two examples of synthetic fibers.
Ans. Nylon, and Rayon.
Q5. Why do we wear clothes?
Ans. Clothes protect the body against heat, cold, rain, dust and insects and look smart and well dressed.
Q6. What is a loom ? rsmaths99.com
Ans. Loom is a machine in which yarn is weaved into fabrics.
Q7. From which part of the plant is jute obtained?
Q8. Name four types of fibrics used by us?
Ans. Four type of fibres used by us are sweater, jacket, shirt, raincoat.
Q9. Name two types of fibres which are obtaind fromplantsand two fibres which are obtained from animals.
Ans. Cotton jute --à Plants
Wool , silk -à Animals.
Q10. Name two plants by which we get fibre.
Ans. Flex, Hemp.
B short answer type question s
Q1. Write two uses of coir fibre.
Ans. Two uses of coir fibre are making carpets and bags.
Q2 List three uses of jute. rsmaths99.com
Ans It is used for making sacks bag, carpets, curtains, ropes etc.
It is used for making cloth for wrapping bags of raw cotton and to makesacks for storing grains.
It is used for making wall hangings for decoration.
Q3. Under what conditions does jute grow?
Ans. Jute grows best in warm, humid climate where the annual rainfall is 150 cm or more. It grows very well in alluvial soil as well as loamy soil.
Q4. How is coir fibre obtained? rsmaths99.com
Ans. Coir fibre is obtained from the outer covering of the fruit of coconut.
Q5. What is sisal?
Ans Sisal is a fibre obtain from the leaves of the sisal plant and it is used for making ropes and matting.
Q6. How is hemp useful for us?
Ans. Hemp is tough and used to make ropes, carpets, sacks, bags, cloth and paper . A special kind of plastic is also made from hemp fibre.
Q7. What kind of soil does cotton require to give good results?
Ans. Black soil and alluvial soil.
Q8. Why do we wear dark coloured clothes in winters?
Ans. Dark coloured clothes are worm in winter because they absorb the heat and become warm quickly.
Q9. How did people cover their bodies before inventing cloths?
Ans. Humans started covering their bodies with big leaves or bark of trees and animal skins or furs.
Q10. Diffrentiate between ginning. rsmaths99.com
Spin Ginning is the process of removing cotton
seed seed from the cotton fibre.
The process of making yarn from fibre is called spinning
It is done by passing harvested cotton through roller gins or by combing manually.
Spinning is done on a large scale with the help of spinning machines.
C. Long answer type questions rsmaths99.com
Q1. Name the processes involved in making fabrics from cotton fibres.
Ans. The process involved in making fabrics from cotton fibres are:
1) Ginning 2) Spinning 3) Dyeing 4) Weaving 5) Knittting
Q2. Write short notes on hemp, flax and sisal.
Ans. Hemp -à Hemp fibre is obtained from the hemp plant. It grows well in loamy soil. It is tough and used to make ropes, carpet sacks, bags, cloth and paper.
Flax-àIt is obtained from the stem of the flax plant . It is used for making clothes, ropes and high quantity.
Sisalà Sisal is a fiber obtained from the leaves of the sisal plant. It is used for making ropes and matting.
Q3. Differentiate between fibres and fabrics.
A fibre is a thread which is strong and flexible enough to make clothes.
Fabric is made from yarn by weaving and knitting.
Fiber are made into threads on spinning machines.
Fabrics are made when dyed yarns are passed through looms.
Q4. Which material is used to make your school uniform?
Ans. Cotton. rsmaths99.com
Q5. Write a short note on the history of clothing.
Ans. During the stone age, humans started covering their body with big leaves or bark of trees and animal skins or furs. Later on when human beings turned into agriculturists, they learn to weave things and greases into fabrics. The early man used cotton as well as flax for making fabrics. They used to wear unstitched clothes. With the invention of seuring needle, people started stitching to make different types of cloths.
Q6. Write about the different processes of making cotton yarn.
Ans. The different processes of making cotton yarn are; rsmaths99.com
1) Ginning à Ginning is the process of removing cotton seed from the cotton fibre. It is done by passing harvested cotton through roller gins separating fibres from cotton seeds was done by combing manually.
2) Spinning à The process of making yarn from fibre is called spinning . It is done on a large scale with the help of spinning machines.
3) Dyeingà The process of colouring clothes is called dyeing.
4) Weaving à The process of making two sets of yarns together to make fabric is called weaving is done by weavers on a loom. These looms are either hand operated or power operated.
5) Knitting à Knitting is a single yarn. It is used to make a piece of fabric. It is done by hand or machines.
Q7. Which steps involved in getting fibre from cotton bolls? Explain them.
Ans. Ginning and spinning are involved in getting fibre from cotton bolls.
Q8. What are the uses of cotton?
Ans. Uses of cotton are; rsmaths99.com
1) It is used to manufacture cotton textiles and undergarment.
2) It used as fillers in pillows, quilts and mattresses.
3) It is used for making surgical bandages.
4) It is used for making clothes, sarees, bedsheets etc.
Q9. Different kinds of cloths are used in different climates and occasions-what do you understand by it? rsmaths99.com
Ans. Summer èPeople living in hot countries wear very light coloured and loose fitting clothes to keep the body cool.
Winter èPeople living in very cold countries wear clothes made from the fur and skin of animals to keep themselves worm. These clothes keep the body worm by not allowing the body heat to escape
RainyèIn rainy seasons we wear synthetic clothes because they do not absorb the water and dry easily.
SORTING MATEPHORS INTO GROUPS
Very short answer type Questions:-
Q1. On what basis do we classify things around us in different groups?
Ans. We classify things around us in different groups based on their similarities and differences.
Q2. Name two liquids that are transparent.
Ans. Water, alcohol rsmaths99.com
Q3. What is the need for grouping objects?
Ans Grouping objects helps us to group similar things and distinguish them from other things.
Q4. What type of surfaces do rough materials have?
Ans. Rough materials have bumps or ridges on their surfaces which can be felt by touching them.
Q5. Name four materials which flot on water.
Ans. Wood, plastic, dried leaves, paper.
Q6. Write the name of three opaque materials.
Ans. Wood, paper, plastic. rsmaths99.com
Q7. Name two materials which have shiny surfaces.
Ans. Gold and silvers.
Q8 Naturally occurring à wood and stone
Man-made materials à plastic, paper
Q9. Give two examples of each translucent and transparent objects.
Ans. Translucent à butter paper, oiled paper
Transparent à glass, water
Q10. Why mustard oil does not mix well with water?
Ans. Mustard oil does not mixwell with water because it is immisable.
B. SHORT ANSWER TYPE QUESTIONS;-
Q1. What does the word classification mean?
Ans The process of grouping things based on similarities and dissimilarities is called classifaction.
Q2. Why is it essential to classify things?
Ans. It is essential to classify things because it makes the study of a large number of objects of different types easier, simple, convenient and systematic. rsmaths99.com
Q3. What is the difference between a rough and smooth material?
Ans. Rough materialà Materials havebumps or ridges on their surfaces which can be felt by touching them. Eg. Rocks, sand paper.
Smooth material à materials which do not have bumps eg- plates cups, window frames. rsmaths99.com
Q4. Differentiate between miscible and immiscible liquids.
The lliquid which get mixed with water completely are called miscible liquid.
Liquid which do not get mixed with water and form a separate layer on keeping for some time.
Eg. Milk, juice
Eg. Kerosene, petrol
Q6. Why does not petrol completely mix with water?
Ans. Petrol is not miscible in water. rsmaths99.com
Q8. Write any three important properties of matter.
Ans. Three important properties of matter are hardness, roughness and solubility.
Q9. Give two examples of each gases that soluble in water and gases that soluble in water and gases that insoluble in water.
Ans. Two examples of gases that are soluble- carbon dioxide, oxygen.
Two examples of gases that are insoluble – nitrogen, methane.
C. LONG ANSWER TYPE QUESTIONS:- rsmaths99.com
Q1. How wii you determine the hardness of a given substance?
Ans. We will determine the hardness of a given substance by touching or feeling if the materials have bumps or ridges.
Q2. How will you know whether a jug of plastic will sink or float?
Ans. WE will know whether a jug of plastic will sink or float by droping them in water. rsmaths99.com
Q3. Oxygen and carbon dioxide are slightly soluble in water. What is the importance of each of these above gases in water?
Ans. The oxygen dissolved in water helps aquating plants and animals carbon dioxide dissolved in water helps the plants living in water for photosynthesis.
Q4. Describe an activity to show that edible oil is an immiscible liquid.
Ans. Take two tumblers containing some water. Add a few drop of alcohol to one tumbler and edible oil to the second tumbler. Shake them well and wait for 5 minutes. You will find that alcohol has completely mixed with water. So alcohol is an example of a miscible liquid. Edible oil forms a separate layer over water. So edible oil is insoluble in water. It is an example of an immiscible liquid. rsmaths99.com
Q5. Write the physical properties of metals.
Ans. physical properties of metals are that they have luster, hardness and opaque in nature.
Q6. Describe an activity to show that test of solubility of following substances: salt, sugar, sand, sawdust, glucose.
Ans. Take five test tubes and mark them as A,B,C,D and E. Add small amount of common salt, sugar, sand, sawdust, glucose respectively into these test tubes. Stire the contents and wait for a few minutes. You will notice that salt, sugar and glucose have completely dissolved in water where as sand dust and sand remain insoluble.
Q8. Differentiate between rsmaths99.com
Transparent à materials through which we can see easily. Eg. Glass, air.
Translucent à a substance through which we cannot see clearly eg.-muddy water, butter paper.
Opaque à a substance through which we cannot see eg.- wood, stone.
Q9. Hard materials à Materials have lumps or ridges on their surfaces. Which can be felt by touching them. Eg.- rocks, sand paper etc.
Soft materials à Smooth materials do not have bumps. Eg.- petals of flower etc.
Q10. Why an iron nail can be sink in water but a wooden block cannot? Give reason for it.
Ans. Iron nail- havier than water and wood is lighter than water.
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SEPARATION OF SUBSTANCES
Very short answer type questions:-
Q1. What type of mixtures can be separated by hand picking?
Ans. The difference in size, shape or colour of different substances can be separated hand picking.
Q2. What is a saturated solution?
Ans Saturated solution is a solution which cannot dissolve more of the solute in it at a given temperature.
Q3. When is sieving method preferred?
Ans. Sieving method is preferred to separate a mixture in which components are of different sizes.
Q4. How is threshing done?
Ans. The threshing of paddy is traditionally carried out by beating the harvested crop with sticks. The threshing of wheat and other crops is carried out by treading the crop with animals such as bullocks and buffaloes. However, in case of big fields, threshing is done by using threshers.
Q5. What is the importance of a thresher to a farmer?
Ans. Using threshers is not only economical but also quicker and more efficient than treading with animals.
Q6. What properties would you look for to prove whether a particular substance is pure or impure?
Ans. By finding its melting point, boiling point and specific gravity we can prove whether a particular substance is pure or impure.
Q7. What is the function of candle in home water filters?
Ans. The candle of the home water filter retains solid impurities but allows the clear water to pass through it.
Q8. Name the method used to separate oil from water.
Ans Sedimentation and decantation wing a separating funnel.
Q9. Name the process by which pebbles and stones are removed by sand.
Ans. Hand picking.
Q10. Milk is said to be a mixture . name its various components.
Ans. Water, carbohydrates, proteins, fats, vitamins and minerals.
B SHORT ANSWERS TYPE QUESTIONS:-
Q1. What is threshing and why is it done?
Ans. Threshing is the process of beating out the grain from the chaff.
Q2. What is sieving and where do we use it?
Ans. Sieving is the process used to separate mixture containing components of different size, shape and colour. We use it in sieving flour, straining tea and straining juice.
Q3. What is the importance of thre- stage water purifier to human beings?
Ans. The importance of three – stage water purifier to human beings is to remove colour and odour, and finally the water passes through the ultraviolet rays which kills harmful microorganisms present in it. Thus the water becomes safe for drinking for us. rsmaths99.com
Q4. What principle do we use in the sepration of mixtures?
Ans. Differences in the properties of substances can be use for separation of mixtures.
Q5. How is winnowing done?
Ans. The mixture to separate grain from husk is made fall from a height. The grains which are heavier fall vertically down on the ground. The husk which is lighter is carried away by the wind and forms a separate heap at a short distance from the heap of grains.
Q6. How will you separate sugar and chalk powder?
Ans. We can use sedimentation and decantation. By sedimentation chalk powder will settle down as sediment. By decantation the water containing dissolved sugar can be decanted and then evaporated to get sugar crystals.
Q7. Why do we need to separate different components of a mixture?
Ans. To separate different components of a mixture
i) Remove undesirable or unwanted components.
ii) Get a pure sample of a substance
iii) Extract useful components from the mixture.
iv) Remove harmful components. rsmaths99.com
Q8. How will you separate salt from brine solution?
Ans. Heat the china dish on a tripod stand after pouring some common salt solution. After sometimes the water starts evaporating we will notice that some white solid substance is left behind as a residue. This is the sample of pure salt.
Q9 Differentiate between saturated and unsaturated solution.
Ans. Saturated à a solution is said to be saturated when a solvent can dissolve no more of a solute at a particular temperature.
Unsaturated à A solution is said to be unsaturated when it is capable of dissolving more of solute then it already contains at the same temperature.
Q10. What do you understand by super saturated when it contains more of the solute than could be dissolved by the solvent under normal conditions. Eg.- carbonated water, beer.
C LONG ANSWER TYPE QUESTIONS:-
Q1. How would you obtain clear water from a sample of muddy water?
Ans. Make a mixture of muddy water and clear water in a beaker. Allow the mixture to stand for sometime you will observe that mud particles starts settling down at bottom of the beaker. The process of settling of heavier particles from a mixture is called sedimentation. The clear water above the sediment is gently poured off into another beaker. This process of transferring the clear liquid without disturbing sediments is known as decanta----. rsmaths99.com
Q2. How will you separate a mixture of common salt, sand and iron fillings?
Ans. Using magnet we can separate iron fillings from the mixture. Then we will take salt and sand, add water to it and filter. This will seprate sand. Then we will boil the filtrate to get salt.
Q3. What are pure substances? Why is it difficult to keep substances in pure form in nature?
Ans. A pure substance is one which is made up of only one kind of a substance or substances. It has a definite, well defined set of properties. Eg.- pure water, gold. It is difficult to keep substances in pure form in nature because they tend to combine with other substances to form compounds and mixtures.
Q4. How will you separate a mixture of water and sulphur?
Ans. Place the funnel containing the filter paper cone in a funnel stand with beaker below. Power the mixture on the filter paper with a glass. The liquid collected in the beaker is pure. The clear liquid obtained after filtration is called filtrate. The filter paper is gently removed from the funnel and is dried to remove the sulphur.
Q6. What is filtration? How is it useful to us?
Ans. The process of separating an insoluble solid from a liquid by using filtering device is called filtration. Filtration is often used in our homes, laboratories and industries, preparing tea or coffee, making cottage cheese, purifying water filtrating sewage water etc.rm of sol
Q7. What do you understand by solution? Explain it with in term of solute and solvent.
Ans. A solution is a homogeneous mixture of one or more substances ( solute) dissolved in another
( solvent). The major component is called solvent and the minor component is called solute. rsmaths99.com
Q8. Give two difference between pure substance and mixture.
A substance which is made up of only one kind of substance is called pure substances.
Mixture is made up of two or more substances.
It has the same composition throughout.
The components may be mixed in any
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L-6 CHANGES AROUND US
A VERY SHORT ANSWER TYPE QUESTIONS:
Q1. What is a change? Explain with the help of a suitable example.
Ans. When something is transformed into other things it is called a change. Eg. Ice melts on heating.
Q2. What type of changes are classified as reversible.
Ans. A change which can be reversed and no new substance is formed is called a reversible changes.
Q3. What type of change produces an entirely new product?
Ans. Chemical change
Q4. List two conditions which help in bringing about a change.
Ans. Contact and heat.
Q5. Name four different type of changes.
Ans. Reversible change, Irreversible change, Physical change, Chemical change.
Q6. What type of change is involved in burning of a fuel?
Ans. Chemical change
Q7. Identify two changes that can be reversed while preparing dish at home.
Ans. Physical change, Irreversible change.
Q8. Why we said that change of seasons is a periodic change?
Ans. Change of season is a periodic change because it changes after regular intervals of time.
Q9. Is burning of coal is physical change?
Ans. No, burning of coal is not a physical change.
Q10. Give two examples of irreversible change.
Ans. Two eg of irreversible change are ripening of fruits, burning of crackers.
B SHORT ANSWER TYPE QUESTION
Q1. Give four examples of reversible changes occurring around you.
Ans. Four examples of reversible change are;
i) Switching of electric bulb
ii) Touching the leaves of an touch-me-not-plant
iv) Inflated balloon
Q2. What is a reversible change ? Can all the changes be reversed?
Ans. A change which can be reversed and no new substance is formed. No, all the changes cannot be reversed.
Q3. Differentiate between a physical change and a chemical change.
A change in which only the physical properties of a substance change.
A change in which the chemical composition of a substance change,
Physical changes are usually reversible and temporary.
Chemical change are usually irreversible and permanent.
Q4. What is an irreversible change? Give two examples.
Ans. A change which cannot be reversed and a new substance is formed is called irreversible change. Eg.- ripening of fruits, burning of crackers.
Q5. Give two examples each of physical and chemical changes.
Ans. Physical – Drying of wet clothes and tearing paper into pieces.
Chemical -- Respiration and formation of compost.
Q6. Do you agree that all physical changes are reversible?
Ans. No, all physical changes are not reversible. Tearing of paper is irreversible.
Q7. Mention any two methods to prevent food from spoiling.
Ans. Two methods to prevent food from spoiling are refrigeration, salting.
Q8. Describe with an activity to show that melting of wax is a physical change.
Ans. First take a candle. Then heat the candle. The wax under the wick get heated and melts. The molten wax flows down and solidifies. The change in state from solid to liquid and again from liquid to solid. This is an example of physical change.
Q9. Are all physical changes reversible? Justify your answer.
Ans. No, all physical changes are not reversible. Tearing of paper is irreversible.
Q10. Can we get milk from curd again? What type of change it can be shown?
Ans. No, we can’ t get milk from curd again. It can be shown as chemical change.
LONG ANSWER TYPE QUESTIONS:
Q1. Give four example each of reversible and irreversible changes.
Ans. Four eg of reversible changes are-
i) An electric bulb
ii) Leaves of the touch – me- not plant.
iv) Inflated balloon.
Four eg of reversible changes are –
i) Ripening of fruits
ii) Curdling of milk
iii) Cooking of rice
iv) Bursting of crackers.
Q2. List three characteristics of reversible changes .
Ans. Three characteristics of reversible changes are-
i) No new substance is formed.
ii) The change is temporary.
iii) The change can be reversed.
Q3. How can you say that burning of a candle is an irreversible change?
Ans. We can say that burning of a candle is an irreversible change because no new substance is formed .
Q4. Describe the conditions that favour a chemical change.
Ans. The conditios that favour a chemical change are –
Contact àAchemical reaction between two substances takes place only when they are brought in close contact with each other.The closer the contact, the better is the chemical reaction.
Heat à Heating is necessary for some chemical changes to take place.
Other conditions which favour changes are types of solutions, light, electricity, pressure and catalyst.
Q5. How can you say that interaction is essential for change? rsmaths99.com
Ans. We can say that interaction is essential for change because almost all changes around us involve two or more materials which interact with each other during the change. Eg.- cutting of wood with an axe. After repeated use, the axe gets a little bit blunt. Thus, the change affects boyh the materials.
Q6. What is the difference between the changes:
i) Rolling of chapatti from dough and
ii) Baking of chapatti.
Ans. Difference between the changes are
Rolling of chapatti from dough – Physical change
Baking of chapatti – Chemical change
Q7. In what way contact and heat favour the chemical change.
Ans. Contact àA chemical reaction between two substances takes place only when they are brought in close contact with each other. The closer the contact, the better is the chemical reaction.
Q8. Differentiate between the following with examples:
i) Look B Q3.
ii)Reversible and irreversible change
A change which can be reversed and no new substance is formed.
A change which cannot be reversed and a new substance is formed.
Eg.-switching of an electric bulb
Eg.- ripening of fruits.
C Q3.How can you say that burning of a candle is an irreversible change?
Ans. When a candle burns, the solid wax changes into liquid and then vapourises. These wax vapour burn to form carbon dioxide and water vapour. Since new substances are formed. This is an irreversible change. rsmaths99.com
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WATER A NATURE’S GIFT
A VERY SHORT ANSWER TYPE QUESTIONS:-
Q1. Name three sources of surface water.
Ans. Three sources of surface water are
ii) River or lake water rsmaths99.com
Q2. Name the purest form of natural water.
Ans. Rainwater is the purest form of natural water.
Q3. Which is the biggest source of water on earth?
Ans. Rainwater is the biggest source of water on earth.
Q4. Name three diseases caused by using unclean water.
Ans. Three diseases caused by using unclean water are
Q5. Which is required to regulate our body temperature?
Ans. Water is required to regulate our body temperature.
Q6. By which process plant release water vapour?
Q7. The amount of useable water in the world is limited so we should take care not to waste water.
Q8. Three types of underground water are:-
i) Well water
ii) Spring water
Q9. What about the two effects of drought on plants.
Ans. Two effects of droughts on plants are
i) Sands do not germinate at all.
ii) Plants dryup and die out because of lack of water in the soil.
Q10. Give two cause of flood. rsmaths99.com
Ans. I) Heavy continuous rains
iii) Cyclones which bring heavy rain.
B SHORT ANSWER TYPE QUESTIONS:
Q1. What are the use of ground water?
Ans. Uses of groundwater are for drinking, cooking, taking bath and washing.
Q2. In what way are rains important to us?
Ans Rains are important to us in irrigation, they clean the air, increase the surface of water level.
Q3. What are the reasons for lowering of the water table in big cities?
Ans. The increase for lowering of the water table are excessive uses, overpopulation, industrializations urbanization and deforestation.
Q4. How are natural springs formed?
Ans. When the rainwater accumulates over the impervious rocks under the earth. Sometimesthis water exerts pressure and comes out of the earth’s surface in the form of a spring from any available opening.
Q5. What will you do to conserve water at home?
Ans. We can conserve water at home in many ways:-
i) Use water judiciously at home for various activities
ii) Take short shower to save water
iii) Make use of water harvesting techniques
iv) Prevent overflow of overhead waterstorage tank.
v) Ensure that pipes, waterpipes and joints do not leak.
Q6. How are clouds formed?
Ans. Heat from the sun turns the water from open water reservoirs and plants into water vapours.
Watervapour, being lighter, rises up in the atmosphere and cools down. It further condenses to form tiny droplets. The droplets join together to form clouds.
Q7. State two harmful effects of drought on animals.
Ans. I) They suffer from water – diseases.
ii) Shortage of water affects their health and productivity.
Q8. Why is sea water salty? rsmaths99.com
Ans. Sea water is salty due to presence of water soluble salt.
Q9. When does flooding take place?
Ans. When the river overflows its banks because of excessive rain, cyclone, tidal waves and a blocked river due to landslide and the water spreads in the surrounding areas, completelysubmerging them.
Q10. Why do we get tired after being out in sun for a long period?
Ans. Because our water loss due to sweating.
C LONG ANSWER TYPE QUESTIONS:
Q1. List five important uses of water
Ans. I) As a part of food for drinking water.
Ii ) For irrigation
iii) As a universal solvent.
iv) As a habitat for marine life.
v) For putting out fire.
Q2. Difference between: rsmaths99.com
Surface water is that which is present on the surface of the earth.
Underground water is that which is present under the soil over impervious rocks.
It is of three types a) Rain water b) River or lake water c) sea water
It is of two types a) well water b) spring water
Q3. What do you mean by rain water harvesting? How is it useful to us?
Ans. The process of collacting and storing rain water from the rooftop of buildings is called rainwater harvesting. It is one of the method to conserve water.
Q4. Explain how evaporation and condensation help in completing water cycle.
Ans. Evaporation takes place from all the open surfaces of water such as rivers, ocens, lakes and ponds. The sun provides the energy necessary for evaporation. Heat from the sun turns water from open water resrervoirs and plants into water vapour. This is called condensation. This Circulation of water from the surface of earth to the atmosphere and back to the earth from the water cycle.
Q5. List of importance of water table.
Ans. Underground water is available for human use either as well water or spring water. However, this water may contain soluble salts of calcium and magnesium.
Q6. Explain the percentage distribution of total available water for human use.
Ans. Out of total water available on the earth 3% of water is freshwater. 68.7% of the total freshwater is frozen as icecaps and glaciers and 30.1 % occurs as ground water. Out of the remaining 1.2 % , about 0.9% occurs as moisture in soil, air and in bodies of living organisms. The rest of 0.3 % constitutes fresh surface – water sources such as rivers and lakes.
Q8. Explain the formation of water cycle.
Ans. Water cycle consists of four steps evaporation ,condensation, precipitation and flouring back to ocean. Evaporation takes place from all the open surfaces of water such as rivers, seas, lakes, ponds,. Heat from the sun turns the water from open water reservoirs and plants into water vapour. The droplets join together to form clouds. As they get cooler they droplets become bigger and heavier and fall as rain. This circulation of water from the surface of earth to the atmosphere and back to the earth forms the water cycle. rsmaths99.com
Q9. Explain the causes and effects of drought and flood.
Ans. Drought occurs when there is enough rai for a long time to recharge natural sources of water. Drought conditions prevail, when normal water needs of agriculture, livestock and human population are not met. Effects of drought are:-
i) It becomes barren for cultivation
ii) People migrate to other economically productive places.
iii) Shortage of water affects their health and productivity
iv) Seeds do not germinate at all
v) There is no change of recharging water reserve
Cause of flood are
i) Heavy continuous rains.
ii) Cyclones which bring heavy rain.
iii) Landslides which may block the rivers.
iv) Tidal waves, like a tsunami.
Effect of flood are:-
i) Top fertile soil gets eroded
ii) Large scale destruction of property which makes the people homeless.
iii) Floods result in death of domestic animals by getting around and often being carried away by the flow of water.
iv) It causes over flouring of water reservoirs. rsmaths99.com