Samacheer kalvi 6th std science book

 

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    Samacheer Kalvi 6th Std Science Book

    4 hours ago New & Old Samacheer Kalvi Books Pdf Download Online 6th, 7th, 8th, 9th books for academic year – for 1st std, 6th std, 9th std, 11th std. 6th social science book pdf free download, tn school 6th maths book pdf. Tamil Nadu 6th Class School Textbooks Online: Studyguideindia provides Class 6st Tamil Nadu state board State Wise School Text Books Download. TNPSC - Science Text BOOK 6th Standard - Free ebook download as PDF Need of standard units To measure anything, we need a unit of the quantity. Tamilnadu Govt Samacheer Kalvi English th Std Common Syllabus

    You are on page 1of Search inside document 1. Our Earth We live in the world, called the planet Earth. We can see the trees, rivers, mountains, animals, deserts and oceans on the Earth. We see the Sun in the day time but not during the night. We see the new moon and full moon. We can see the stars. If you see the surface of the Earth, where you are living, it will be a flat. Actually, Earth is not flat. It is in spherical shape like a ball. Astronauts travelling in spaceships had seen the Earth from large distances. They took photographs of the Earth from space Fig. Photographs taken by the astronauts from spaceships clearly show that the Earth is spherical in shape.

    Kilometre, millimetre, centimetre, metre. The value of one division of a measuring cylinder is one ml. Water is poured into it, so that its level is at 50th division. When a stone is put in the cylinder, the level of water rises to 75th division. What is the volume of the stone? Identify the mistake and correct it. State True or False a Hand span is a standard unit for measuring length.

    What is the area of a rectangular field m long by 60 m wide? What is the volume of a block of metal 6 cm long, 5 cm wide and 4cm high? What is the volume of the metal cube with side 5 cm? Name the balance used in science laboratory. State two examples for periodic motion. What is the necessity of standard units in measurement?

    What are the conventions used in writing the unit and their symbols of SI system? State two precautions, which should be taken while using a metre scale. How will you measure the thickness of a coin?

    How will you measure the volume of a stone? The milkman gives you a half litre pack milk. How will you verify the volume of milk?

    Find out the area of your science book? Find out the volume of your science book. Estimate the area of the blackboard in your class room in square metres. Estimate the floor area of your class room in square metres. Estimate the volume of your class room in cubic metre. Nature of matter We see many living and nonliving matter around us in this Earth. You will study about living things in Chapter In this chapter you are going to learn about non-living matter.

    In our day-to-day life we see and use many non-living things like stone, sand, table, iron rod, water, milk, air etc. So learning about these things is quite necessary. Fill it with dry sand and lift it again. You feel it heavier now. Don't you? From this you understand that sand has mass Fig. Now try to add more amount of sand into the bucket. The sand begins to fall out. The bucket cannot hold any more amount of sand as it is already full.

    The sand has occupied the entire space. From this you understand that sand occupies space. The space occupied by matter is called as volume. Lift an empty iron bucket and feel its weight. Fill it with water and lift it again. From this you understand that water has mass Fig. Now pour more amount of water into the bucket. Water overflows. The bucket cannot hold any more amount of water as it is already full. Water has occupied the entire space. From this you understand that water occupies space.

    Take a deflated ball and keep it on the left pan of a balance. Add some sand on the right pan gradually till the pointer comes to zero. Now take the ball and inflate it with air. Place it again on the left pan. Now you can see the pointer moving to the left side. Add more amount of sand to the right pan till the pointer again comes to zero Fig. From this you understand that 'air has mass'. Now allow the air to get out of the ball.

    Ball shrinks in size. Doesn't it?

    From this you understand that air occupies space. What is matter made up of? Matter is made up of very tiny uniform fundamental particles. These particles cannot be seen with our eyes. The particles are held together by an attractive force.

    The nature of the fundamental particles and the strength of the attractive forces among them vary from one substance to another. These fundamental particles may be atoms, molecules or ions. Solid Book, chair, pen, stone, sand and ice are in the solid state. The particles in a solid are packed very closely to each other and are held together by strong attractive forces Fig. We conclude from the above activities that matter substance like sand, water and air have mass and can occupy space.

    Feelings like sorrow, happiness and pain have no mass and cannot occupy space.

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    So these are not considered as matter. Activity 3. Take a glass tumbler and plunge it into the water as shown in the Fig. Water does not enter the glass tumbler beyond a level.

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    Now tilt the tumbler slowly to a slanting position. You can see the air bubbles coming out of the tumbler and Air Air Bubbles.

    Liquid Milk, water and fuels like petrol and diesel are in the liquid state. The particles in a liquid are not very close to each other. The distance between them is greater when compared to a solid Fig. The attractive force between them is also weaker. Solids have definite shape and volume.

    When the temperature remains constant, they do not change their shape or volume. Observe the shape of water. It has the shape of the beaker. Transfer this water into a ml conical flask. Now the water gets the shape of the conical flask Fig. But the volume of. Gas The air we breathe is a gaseous substance. The fundamental particles in a gas are held together by weak forces of attraction.

    The distance between them is also greater than that in a liquid Fig. The stone has a definite shape and volume. Now place the stone on the floor. It has the same volume and shape. Place it in a glass tumbler. Now also you do not find Liquids like water and oil have definite volume. But they do not have definite shape. They get the shape of the containers in which they are kept. Since the force of attraction between the particles in a liquid is weaker, they are capable of moving.

    So they can change their shape. The two inflated balloons differ in shape.

    The air inside the two balloons get the shape of the balloons Fig. They get the shape and volume of the containers in which they are kept. You feel it hard and rigid. Solids contain particles which are closely packed. The particles have strong forces of attraction between them. So they are rigid and have high density. How do you feel when you touch water or when the gentle breeze touches you?

    You feel them softer. The reason is that the particles in a liquid and gas are comparatively far apart. They are held together by weak forces of attraction. So the liquids and gases are highly flexible, soft and have lesser density than solids. Density of gases is less than that of liquids. Does it move on its own? It does not move towards lower level. Since the particles in a solid are bonded strongly, they do not separate easily and move.

    Solids do not show the property of fluidity. Pour some water on an uneven surface. You can see the water running from higher level to a lower level Fig.

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    Fill a ml jar with g of brown nitrogen peroxide gas. The gas jar appears brown all over. The volume of the gas is ml. Fill the same amount of gms of nitrogen peroxide in a ml jar. Now also you can see the gas jar appearing brown all over. Now the volume of the gas is ml.

    See Fig. So they can move easily. Liquids show the property of fluidity. Water flows from mountains down into rivers due to this property. The sugar disappears by completely mixing with water. Solids like sugar and salt dissolve in water. So the sugar particles separate and mix with water. Place an iron ball in a beaker containing water and stir it. What do you observe? Iron ball does not dissolve in water.

    From this you understand that some solids are soluble and some solids are insoluble in water. Prick an inflated balloon with a pin. The air inside the balloon comes out with a force and noise Fig. What is the reason? The particles in a gas are far apart from each other and are held together by very weak forces of attraction. So they move very easily. Gases have the property of fludity. Solubility of liquids Add a small quantity of ethyl alcohol to water.

    Alcohol completely mixes with water. Alcohol is completely soluble in water. Add a few drops of coconut oil and stir well. You will understand that oil does not mix with water. Oil is insoluble in water. Solubility of gases How do aquatic living things breathe?

    Oxygen present in the air is soluble in water. So they breathe the oxygen dissolved in water. The marine plants take the carbon-di-oxide dissolved in sea-water for the photosynthesis. The soda water, we drink, is containing dissolved carbondi-oxide gas.

    Generally gases are soluble in water but certain gases like hydrogen and nitrogen are insoluble in water. The substances which are insoluble in water may be soluble in some other solvents. Paints are insoluble in water. But they are soluble in kerosene. Pour some water in each. Add a small quantity of sand in the first test tube, salt in the second test tube and starch powder in the third one and shake them.

    Sand does not dissolve in water. Salt completely dissolves. Starch powder is partially soluble. Do you observe any change in volume? The volume of iron piece does not change.

    When pressure is applied over liquids their volume does not decrease. Place that end on a table and press the piston of the syringe downwards. The volume of the water does not decrease. When pressure is applied over gases, their volume decrease considerably. Since the distance between the particles of a gas is more, they come closer when pressure is applied. Air is sucked in. Close the open end with a cork. Keep the closed end on a table and press the piston downwards.

    The piston moves easily as the air in the syringe gets compressed. Change of state due to heat i Solid liquid Take out some ice cubes from a refrigerator. Place them in a cup and heat it. Solid ice melts into liquid water.

    The transformation of a solid matter into liquid when heated is called melting. The ice-deposits in the Himalayas melt due to heat of the Sun and flow as Ganga and Brhamaputra rivers. Water boils and vapours of water steam come out.

    The transformation of a liquid into vapour by heating is called evaporation. The sea water evaporates due to Sun light and forms clouds in the sky. Steam gas heat Ice solid heat Water Liquid.

    Certain solids when heated, are converted to vapour state without passing through the liquid state. This is called sublimation. Substances like naphthalene, benzoic acid, iodine and ammonium chloride have the property of sublimation.

    Heat it. Stop heating and observe the change. Change of state due to cooling i Gas Liquid We enjoy when it rains. How do we get the rain from the sky? The water vapour in the cloud gets cooled and forms tiny particles of water. These water particles unite and form water drops which fall as rain. It does not melt into a liquid.

    But it evaporates into vapour. Observe the outer surface of the tumbler after sometime. What do you see? What do you understand? Water drops get collected on the outer surface of the tumbler. This is due to the condensation of water vapour present in the atmospheric air.

    Or you must have seen such deposits of ice in the television pictures. How does the ice get deposited on the mountains? Water gets cooled due to severe cold climate at high altitude and converted to ice. These ice particles deposit over the mountains and trees during winter Fig. The transformation of a liquid into solid due to cooling is called freezing. The following representation gives you a clear understanding of change of states of matter.

    Diffusion of a gas in a gas When you return from school in the evening, you must have smelt the nice odour of your mother's spicy tiffin. How are you able to get the smell of the food being prepared in the kitchen while you are at the entrance of your house?

    Visit an ice factory and see how ice creams are made. The vapours of the cooked food come out. The forces of attraction between the particles in a gas or vapour is very weak.

    So the particles separate and mix with the particles of. When you breathe that air mixed with vapours of cooked food you feel the smell of the food. You will feel the pleasant odour of the agarbathi all over that room.

    This happens due to the diffusion of the vapours of agarbathi in air. Diffusion of a liquid in a liquid Pour a drop of blue ink into a beaker of water. The particles of ink diffuse through the particles of water and the whole water in the beaker turns blue. Liquids diffuse slower than gases.

    Diffusion of solids in liquid Drop a small piece of potassium permanganate carefully into a beaker of water.

    You can see the pink colour of the crystal slowly diffusing through the water as the crystal dissolves. The attractive force between the particles of potassium permanganate is removed by the particles of water. So the potassium permanganate particles get diffused in water.

    Since the particles of a solid have strong forces of attraction, diffusion of a solid in another solid does not take place naturally. This material, capable of leading in the proper direction is called as loadstone. A magnet has two poles namely North pole and South pole. Poles are at the end of the magnet where the power of attraction is more. Like poles N-N and S-S repel each other.

    Unlike poles attract each other N-S and S-N. A magnet attracts iron, nickel and cobalt.

    Magnets have no effect on wood, glass, aluminium, water, paper and plastic. These are known as non-magnetic substances. We are using the magnets in cranes to lift a heavy load See Fig. To remove any iron particle from the eyes, magnets are used. Impurities of iron could be removed from other metals using magnets.

    Magnets are available in electric bell, electric fan, telephone and electric motors. We are using the magnets in doors, window catchers, door closers of almirahs and in beds.

    In the materials like wood and plastic, heat flows from one end to another very slowly. Wood, paper, cloth and plastic are bad conductors of heat.

    The metal mercury, which is a liquid, is a good conductor of heat. So, we are using the mercury in thermometers. Gases are poor conductors of heat.

    When we switch on the light or fan or motor, electric current flows through the filament of the bulb or through the coil. Wires or cables carry the electric current. Have you seen the electric cable? Take a piece of unused cable or wire. Cut and open the outer coloured layer insulating material. Inside, you find a number of thin metal wires copper aluminium. These metal wires carry the current.

    Metals are good conductors of electricity. The outer coloured layer will not carry the current. This insulating material, paper, dry cloth and rubber are bad conductors of electricity and are called insulators. Pure water is a bad conductor of electricity. However, water what we are using containing dissolved salts conducts electricity. It is not advisable to touch the water in which electric These vessels are made of metals and also provided with handles made up of wood or some other non-metallic material like plastic.

    Why are the vessels provided with wooden or plastic handles? Take a vessel. Fill it with hot water. Put the two spoons in it. One is made of metal like aluminium or stainless steel and the other is made of wood or plastic.

    After some time, touch the two spoons by your left and right hand. Which one is hotter? The metal spoon is hotter than wooden spoon. Metals quickly conduct heat. So, metals are good conductors of heat.

    In metals, heat flows from one end to another quickly. Wooden spoon Hot water Metal spoon. It is advisible to always wear rubber chappals insulators and to keep the hands dry while operating electrical appliances. Thus, we conclude that matter can be classified as conductors of electricity and insulators.

    Switch it on. Take a paper, a dry cloth, a rubber sheet and an aluminium foil. Place them one by one in between the bulb and cell and check whether the torch lights up in each case. The torch does not light up with paper, dry cloth and rubber.

    But it lights up with the aluminium foil. So aluminium conducts electric current. That is why electric wires are made.

    All these are opaque materials. Light cannot pass through them. We can see through a glass. So glass is a transparent material. We can see the fish in clean water. So clean water is also a transparent material. We are surrounded by air, and objects are always seen.

    So air is also transparent material. We may conclude that the materials which allow the light to pass through them are called as transparent and those which do not allow the light are called as opaque. Which of the following does not change its shape at the room temperature? It has definite volume and mass. During which process the volume of matter increases largely? You can feel the bad smell of the garbage at a distance.

    In thermometers, the liquid mercury is used. If you take equal volumes of water and sand, which will have more weight? How are you able to detect the leakage from a gas cylinder? Does the force of attraction between the particles increase or decrease when a liquid substance is converted into a solid?

    Mention two solids that are insoluble in water. Solids are rigid. But the liquids and gases are not rigid. Liquids flow from higher to a lower level. What do you understand from this? What is evaporation? Give an example. What is matter? Prove by an experiment that air has weight. Give an example to understand the gaseous diffussion. By an experiment how can you prove that volume of a gas can be reduced by applying pressure.

    How do aquatic plants respire? Cooking vessels are provided with wooden handles. When you add a drop of ink to water what will happen? Separation of substances It is very essential that the food we eat, the air we breathe, the water we drink and the different substances we use in our day-to-day life are pure.

    As the environmental pollution is more nowadays, we must remove the pollutants and the unwanted components from them. Let us study about the different methods adopted in our daily life and laboratories to separate and purify the substances.

    Pure substances have the following characters. Definite composition by nature. Definite physical properties such as melting point, boiling point and density. Homogeneous nature. A mixture contains two or more pure substances which can be separated by easy physical methods. Table 4. Pure substances Mixtures i The components of a pure substance are of the same type The components of a mixture are of two or more types.

    Mixtures are heterogeneous in nature. They contain particles of different types. Particles are uniform throughout the substance. Pure substances iii Pure substances have definite physical properties. Add water to it and stir well. Salt dissolves in water. Carefully observe the bottom of the container. You can see a deposit of fine sand. The salt crystals that are obtained from sea water contain particles of sand which do not dissolve in water. So these sand particles settle at the bottom of the container.

    What will happen if we add the salt crystals directly to our food while cooking? Sand particles will mix with our food and affect our health. So, while using crystals of salt for cooking it is better to use the solution of salt in water. Grains like rice, Mixtures Mixtures do not have definite physical properties. They have different physical properties depending upon the components present in it.

    We can easily pick them and separate. If the size, colour and shape of the components are different, it is easy to separate them by hand picking Fig.

    This method is useful to remove the husk from grains like rice, wheat and ragi. Farmers drop the mixture of grains and husk slowly from a height when the wind blows. All living things require water. Light is essential for green plants. Animals need a source of food. They cannot exist in places where the food is not available. Plants use carbon-di-oxide present in the air and sunlight in preparing their food.

    We cannot live without breathing. We get oxygen from the air. Animals living in water like the fish get the oxygen from water Fig. The oxygen is dissolved in water.

    So atmosphere must have oxygen and carbon-di-oxide. Water, atmosphere with oxygen and carbon dioxide, suitable temperature and food are available only in our Earth. Hence, life exists only on the Earth. In the other planets the above said things are not available. So life is not possible in other planets. Choose the correct answer.

    How many planets are in the solar system? Write the name of the planets. Day and night changes alternately in the Earth. Give the reason. What is the time taken by the Earth to complete one rotation? If the day is longer than night, then is it summer or winter? If the night is longer than day, then is it summer or winter? Is our Earth like a solid cricket ball or hollow foot ball? What are three layers of Earth?

    What is called atmosphere? Give the composition of air. What is the use of Ozone layer? Which gas is essential for burning? Name the useful important materials available in the ocean. What is called water cycle? How is soil formed? State the requirements that are essential for the existence of life on Earth. In which layer of the Earth do you expect to find petroleum? If you breathe out over a glass plate, why the glass plate appears misty for some time?

    What happens to water when wet clothes dry? List out the uses of soil. From where do the fish get oxygen? Make a visit to the nearby planetorium and observatory station. List out the events observed.

    Measurement Measurement is necessary in everyday life. If we go to the textile shop to download the cloth for stitching shirt, we do not ask the seller to give one cloth. If we go to the vegetable shop, we do not ask to give a little amount of potato. If we go to the provision store, we do not ask to give a little amount of sugar. What is the journey time of the bus from your village to town?

    In the textile shop, we ask for 1 metre cloth and the seller measures it using a scale. In the provision store, we ask for 1 kilogram or 2 kilograms sugar and the seller measures it using a balance. The journey time of the bus is 30 minutes. In the above cases, we measure the quantities like length, mass and time using a metre scale, a balance and the time watch.

    Hence measuring quantities with units like metre, kilogram and hour or minute plays an important role in our daily life. What is the size of your science book? At what distance your school 13 is located from your house?

    How much milk do you want? What is the area of your class room? What is your mass? What is the time taken by you to complete metre running race? Measurements are necessary to answer such questions. Without measurement we cannot make a correct judgement. A guess or a rough estimate may give a wrong answer. Science is concerned with finding out about the world, Why things happen?

    How things work? Early scientists, the ancient Greeks relied almost entirely on their senses. They were good at observing and at suggesting explanations of what they saw, but without doing experiments.

    For example, Aristotle believed that heavy objects fall faster than lighter objects. But we know it is wrong. Measurements have helped scientists and engineers to understand motion, how aeroplanes fly, how satellites behave, how machines work. Measurements make it easier to describe observations. Careful measurement is an important work of any scientist. See the blackboard in your class room.

    What is its length? Let your answer be 2 metres. Here 2 is the number and metre is the unit of length. That is the length of the blackboard is two times the length of the fixed quantity metre called unit. Let your answer be 30 kilograms. Here 30 is the number and kilogram is the unit of mass. That is, your mass is 30 times the mass of the fixed quantity, kilogram, called unit.

    Thus, every measurement consists of a number and a unit. The comparison of an unknown quantity with some known fixed quantity of the same kind is called measurement. The known fixed quantity is called unit.

    Different units Fig. Long ago, the lengths are measured with the units derived from some parts of the human body. For example, width of four fingers, handspan, a cubit, a pace or a footstep and yard Fig.

    But these units were not reliable because the lengths of body parts are different for different people. For example, your teacher measures the length of the classroom in cubits. Let the answer be 15 cubits. If you measure the same length, the answer may be 20 cubits.

    For the same length of class room, two different answers are given, if we use the unit cubit. Hence, cubit cannot be a standard one. Each measurement must mean the samething to every one. Therefore, everyone must use the common units of measurement called standard units like metre, kilogram and second. SI is the abbreviation of The system International D units.

    In the S I system i the unit of length is metre 15 ii the unit of mass is kilogram iii the unit of time is second 2. The unit of force is newton The unit of work is joule. Symbol for metre is m It should not be as m. Symbol for second is s It should not be as s. Let the answer be 2 Km. Eventhough the distance, that is length is measured by the unit metre, we do not use metres.

    What is the length of your pencil? Let the answer be 15 cm. What is the thickness of the coin? Let the answer be 2 mm. Hi Hariprasad, Thanks for your comment. Will try to upload 6th,9th,11th new syllabus book back questions and answers as soon as possible. Hi Logeswaran, Thanks for your comment. We will upload and send you the same. Kindly check your mail. Weather you can upload the samacheer books book back questions like 1, 2,5 marks answers, we get lot of benefits, thank u.

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