Class 10th Science Activities PDF

Class 10th - Science All Activities + Questions  Burning of a magnesium ribbon in air and collection of magnesium oxide in a watch-glass Activity AASAN BHASHA MEI Samajhte hai:...

Class 10th - Science All Activities + Questions  Burning of a magnesium ribbon in air and collection of magnesium oxide in a watch-glass Activity AASAN BHASHA MEI Samajhte hai: Take about 2 cm long magnesium ribbon. 1.1 Clean it with sandpaper. Hold the magnesium ribbon with a pair of tongs , and start heating its other end. The Magnesium Ribbon starts burning. BUT IT'S NOT BURNING ALONE. It starts burning with a dazzling white flame. And now to collect the Magnesium Oxide Powder hold it over a Watch Glass Activity 1.1  Activity 1.1 Q. Why Magnesium ribbon is cleaned before burning in the air? Ans. The magnesium ribbon which we use usually has a coating of ‘magnesium oxide’ on its surface which is formed by the slow action of oxygen of air on it. So, before burning in air, the magnesium ribbon is cleaned by rubbing with a sand paper. This is done to remove the protective layer of magnesium oxide from the surface of magnesium ribbon so that it may readily combine with the oxygen of air (on heating).  Activity 1.1 Q. Why the magnesium ribbon should be burned by keeping it as far as possible from the eyes? Ans. The dazzling (very bright) white light given out during the burning of magnesium ribbon is harmful to the eyes. So, the magnesium ribbon should be burned by keeping it as far as possible from the eyes.  Formation of Precipitate Activity 1.2 AASAN BHASHA MEI Samajhte hai: (i) Take some lead nitrate solution in a test-tube (or a beaker). (ii) Add potassium iodide solution to it. (iii) A yellow precipitate of lead iodide is formed at once. (iv) A change in colour (from colourless to yellow) also takes place in this chemical reaction. Activity 1.2 Q. What do you observe when potassium iodide solution is added to lead nitrate solution in a test tube? Ans. White lead nitrate reacts with white potassium iodide to form yellow lead iodide which is insoluble in water. Pb(NO3 )2 (aq) + 2KI(aq) → 2KNO3 (aq) + PbI2 (s) Activity 1.2 Q. What is precipitation reaction? Ans. This is a type of reaction in which when two Aqueous soluble solutions Combine/React together to form a semi?soluble Salt and that salt is called as Precipitate. And in any reaction, when Precipitate is formed then, that is called a Precipitation reaction. Q. Give some More Examples of Precipitation Reaction? Ans.  Chemical Reactions that evolve Gases AND Rise In Temperature Activity 1.3 AASAN BHASHA MEI Samajhte hai: (Take some Zinc Granules in a Conical Flask Now on Adding the Sulphuric Acid you will See a Magic. As You will see the bubbles of HYDROGEN GAS forming around the zinc metal We verified that it is Hydrogen gas because its bubbles burnt with pop sound when passed through soap solution (As shown below diagram) Also, if we will touch the flask with our hands we will see that it is too HOT. So we get to know that along with evolution of gas temperature also rises in the Chemical Reactions Activity 1.3 Q. Why is it recommended always to use dilute acids? Ans. There are many reasons But according to your syllabus: Because, If the Concentration of the Acid will be higher than it will be a More Exothermic Reaction and if the activity will not be completed in the presence of the right Mentor then it can be very harmful. To prevent the danger. Because you all know how Acids are harmful If the concentration will be higher it can Even burn the skin. And to prevent Danger, we use the highly dilute Acid. Activity 1.3 Q. What happens when Zn Granules are added to the HCl/H2SO4? Ans. When zinc granules are added to dilute sulphuric acid, there occurs a change in the state of zinc granules and they are converted to zinc sulphate(ZnSO4) and hydrogen gas is evolved. Zn + H2SO4 → ZnSO4 + H2 This reaction is exothermic, i.e., it involves release of heat and so the flask becomes hot and temperature of the system increases.  Decomposition reaction of ferrous sulphate Activity 1.5 AASAN BHASHA MEI Samajhte hai: Take about 2 grams of Ferrous Sulphate Crystals in a DRY Boiling Tube. They are originally Green In Colour Heat the boiling tube over a burner Now You will again see the magic. As the green colour first changes to White And then Finally a Brown Solid is formed(which is ferric oxide) So the main observation of this activity is that the smell of burning Sulphur comes out along with the colour change from Green to White and then Brown. Activity 1.5 Q. Do you observe any change in the colour of ferrous sulphate crystals when they are heated in the boiling tube over the flame of a burner or spirit lamp? Ans. The green colour of ferrous sulphate crystals changes to brownish black oxide and smell of burning sulphur will be observed. Ferrous sulphate decomposes to form ferric oxide (Fe2O3 ), sulphur dioxide (SO2) and sulphur trioxide (SO3). So, the gas emitted smells like burning sulphur. In this reaction, the single reactant FeSO4 decomposes to form three different products. So, the reaction is a decomposition reaction. Activity 1.5 Q. List any two observations when Ferrous Sulphate is heated in a dry test tube? Ans. Observation: Change in color of crystals from green to brown. This is because of the ferrous sulfate crystals on heating will lose water molecules and turn to white which immediately turns brown due to formation of ferric oxide. Activity 1.5 Q. State the observation and inference made by a student when he brings I. a wet blue litmus paper and II. a wet red litmus paper in contact with the gas liberated during thermal decomposition of ferrous sulphate. Ans. When FeSO₄ → Fe₂O₃ + SO₂ + SO₃ (on heating ) (a)Blue litmus turns red (b)No change in red litmus Gas liberated are SO2 and SO3. These are acidic oxides of sulphur, so, it turns blue litmus red and no change in red litmus.  Activity 1.6 Decomposition reaction of lead nitrate AASAN BHASHA MEI Samajhte hai: Take about 2 grams of lead nitrate powder in a boiling tube. Lead nitrate is a colourless compound. Hold the boiling tube in a test-tube holder and heat it over a burner. Brown fumes of nitrogen dioxide gas are evolved which fill the boiling tube. If a glowing splinter is held over the mouth of the boiling tube, it catches fire and starts burning again. This shows that oxygen gas is also evolved during this reaction. A yellow solid is left behind in the boiling tube. This is lead monoxide (Please note that lead monoxide is reddish-brown when hot but yellow when cold). Activity 1.6 Q. What do you observe when a boiling test tube containing lead nitrate powder is heated it over a flame? Ans. On heating lead nitrate decomposes with a crackling sound along with the evolution of brown fumes of nitrogen dioxide (NO2) which has an irritating smell. The gas turns blue Litmus red; hence, it is acidic in nature. A yellow solid residue of lead oxide (PbO) remains in the test tube. Activity 1.6 Q. You want to study a decomposition reaction by taking ferrous sulphate crystals in a boiling tube. List two steps you would follow while doing the experiment. Ans. Take a test tube and dry it completely. Take a small amount of the given sample in the test tube. Hold it with a clamp and heat the tube over a burner. Crystals will first become dirty white and then change to brown.  Decomposition of silver chloride is caused by light Activity 1.8 AASAN BHASHA MEI Samajhte hai: Take about 2 grams of silver chloride in a china dish. It is white in colour. Place this china dish in sunlight for some time. We will find that white silver chloride turns greyish white (due to the formation of silver metal). Silver bromide also behaves in the same way as silver chloride with light energy. Activity 1.8 Q. Why AgCl kept in a Black color of Bottles? Ans. As you know now, AgCl shows a photolytic Decomposition that’s why we kept AgCl in a black color bottle to protect it from the Sunlight. Q. Silver chloride when kept in the open turns grey. Illustrate this with a balanced chemical equation Ans. Silver chloride when kept in the open turns grey. It is a photodecomposition reaction  Displacement reaction between iron (nail) and copper sulphate solution Activity 1.9 Activity 1.9 AASAN BHASHA MEI Samajhte hai: Take about 10 mL of copper Sulphate solution in a test tube. Its original colour is Deep Blue Now take a big iron nail and clean it same like u did with Magnesium Ribbon using the sandpaper. Now put the iron nail in the solution and then see the magic. After sometime like half an hour we will see that the iron nail would be covered with red-brown layer. And this layer would be of our another metal that is Copper. So Finally we will see that the original Deep blue colour has faded and the solution turns to light Green Colour. Activity 1.9 Q. Why does the Iron nail become brownish in color and the blue color of copper sulfate solution fade? Ans. In this reaction, the Iron nail becomes brownish in color and the blue color of copper sulfate solution fade Because Iron displaces Cu (Copper) from its Position (CuSO4) Copper Sulphate. Because Iron is more reactive than Copper and it easily displaces Cu(Copper) from Copper Sulphate(CuSO4). And that’s why the color of CuSO4 solution changes from Blue color to ade because finally the solution of Copper sulfate was got to converted into Iron Sulphate (FeSO4). Fe(s) + CuSO4 (aq) → FeSO4 (aq) + Cu(s) Activity 1.9 Q. On keeping iron nails in a blue coloured copper sulphate solution, it is observed that the colour of the solution turns light green after sometime.Give reasons for this colour change. Name the type of reaction. Ans. It is an example of metal displacement reaction. Iron has displaced copper from copper sulphate solution and has changed to iron sulphate which is light green in colour. Fe(s) + CuSO4 (aq) → FeSO4 (aq) + Cu(s)  Double displacement reaction between barium chloride and sodium sulphate. Activity 1.10 AASAN BHASHA MEI Samajhte hai: Take 3 mL of Sodium Sulphate solution in a test tube. And take 3 mL of Barium Chloride but in another test tube. Add Barium Chloride solution to Sodium Sulphate solution And the magic we see is now of White colour as a White Precipitate is left over in the Test Tube  Activity 1.10 Q. While studying the double displacement reaction, the solutions of barium chloride and sodium sulphate are mixed together. (i) What do you observe as soon as the two solutions are mixed together ? (ii) What will happen in the above observation made by you after ten minutes ? Ans. (i)A white precipitate of barium sulphate is immediately formed. (ii)The white precipitate will settle down at the bottom of the tube and the solution above the precipitate will become colourless.  Oxidation of copper to copper oxide Activity 1.11 AASAN BHASHA MEI Samajhte hai: Take about 1 gram of copper powder in a china dish. It is red brown in colour. Heat the china dish strongly over a burner (see Figure 55). A black substance is formed. This black substance is copper oxide  Activity 1.11 Q. How can the black coating on the surface be turned reddish brown ? Ans. If hydrogen gas is passed over this heated material (CuO), the black coating on the surface turns brown as the reverse reaction takes place and copper is obtained. Q. You might have noted that when copper powder is heated in a china dish, the reddish brown surface of copper powder becomes coated with a black substance. (a)Why has this black substance formed ? (b)What is this black substance ? Ans. A.Black substance is formed is because of the oxidation of Copper. B.The black substance formed is Copper Oxide (CuO).  Reaction of zinc granules with dilute sulphuric acid and testing hydrogen gas by burning Activity 2.3  Activity 2.3 AASAN BHASHA MEI Samajhte hai: Take a few pieces of zinc granules in a boiling tube and add about 5 mL of dilute sulphuric acid to it. We will observe the formation of gas bubbles on the surface of zinc granules. Pass the gas being formed through the soap solution taken in a trough (by means of a glass delivery tube). Gas filled bubbles are formed in the soap solution which rise into the air. Bring a burning candle near a gas-filled soap bubble. The gas present in soap bubble burns with a ‘pop’ sound (making a little explosion). Only hydrogen gas burns making a ‘pop’ sound. This shows that hydrogen gas is evolved in the reaction of dilute sulphuric acid with zinc metal (taken in the form of zinc granules)  TEST for CO2 gas Activity 2.5  Activity 2.5 AASAN BHASHA MEI Samajhte hai: Take a boiling tube and put about 0.5 g of sodium carbonate in it. Add about 2 mL of dilute hydrochloric acid in the boiling tube (through a thistle funnel) We will observe that brisk effervescence of a gas is produced. Pass the gas through lime water. The lime water turns milky (showing that it is carbon dioxide gas). Keep on passing carbon dioxide gas through milky lime water for some more time. The lime water becomes clear again Activity 2.5 Q. A student adds a spoon full of powdered sodium hydrogen carbonate to a flask containing ethanoic acid. List two main observations that he/she must note in his/her notebook about the reaction that takes place. Also, write chemical equation for the reaction Ans. Two main observations during the reaction are: (i)Brisk effervescence (ii)Sodium acetate is formed Chemical equation for the reaction is: 2CH3COOH + Na2CO3 → 2CH3COONa + CO2 + H2O  Are the Crystals of Salts really Dry? Activity 2.15 AASAN BHASHA MEI Samajhte hai: i) Take a tube, add few crystals of copper sulphate and heat it. ii) On heating copper sulphate will start appearing white. iii) Copper sulphate crystals contain water of crystallisation. When heated the crystals, this water is removed and the salt turns white. iv) On adding 2-3 droplets of water, Copper sulphate crystals restore its blue colour.  Most non-metals produce acidic oxides when dissolved in water Activity 3.8 Activity 3.8 AASAN BHASHA MEI Samajhte hai:  What happens when Metals are burnt in Air Activity 3.9 Activity 3.9 AASAN BHASHA MEI Samajhte hai:  What happens when Metals react with Acids? Activity 3.11 Activity 3.11 Q. Which metals reacts vigorously with dilute hydrochloric acid? Ans. Magnesium shows fastest reaction and hydrogen bubble formation. Q. With which metal did you record the highest temperature? Ans. Magnesium Q. Arrange the metals in the decreasing order of reactivity with dilute acids. Ans. Mg > Al > Zn > Fe.  How do Metals react with Solutions of other Metal Salts? Activity 3.12  Activity 3.12 AASAN BHASHA MEI Samajhte hai: i. Put a clean copper wire and put it in a solution of iron sulphate. ii. Put a clean iron nail in a solution of copper sulphate. iii. After 20 minutes, it is observed that blue CuSO4 solution turns green Q. In which test tube did you find that a reaction has occurred? Ans. Test tube containing CuSO4 solution. Q. On what basis can you say that a reaction has actually taken place? Ans. The blue colour of CuSO starts fading. Q. Write a balanced chemical equation for the reaction that has taken place. Ans. Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s) viii.This is a displacement reaction. ie., reactive metals displace less reactive metals from their compounds in solution or molten form  CORROSION Activity 3.14 Activity 3.14 AASAN BHASHA MEI Samajhte hai: Observations after leaving them for a few days: i. The iron nails rust in test tube A, but they do not rust in test tubes B and C, because; ii. In test tube A, the nails are exposed to both air and water. iii. In test tube B, the nails are exposed to only water. iv. The nails in test tube C are exposed to dry air. v. This shows that both air and moisture are needed for rusting of iron  AASAN BHASHA MEI Samajhte hai: Activity 4.5 i. When KMnO4 is added, its purple colour disappears initially. ii. Why does the colour of potassium permanganate not disappear when excess is added? -- Because all the alcohol gets consumed and the reaction stops. Activity 4.8 AASAN BHASHA MEI Samajhte hai: Activity 4.12  Activity 4.12 Foam is formed with difficulty and an insoluble substance (scum) remains after washing with water. This is caused by the reaction of soap with the calcium and magnesium salts, which cause the hardness of water. Hence you need to use a larger amount of soap. This problem is overcome by using another class of compounds called detergents as cleansing agents. Q. In which test tube do you get more foam?- Distilled water test tube. Q. In which test tube do you observe a white curdy precipitate?- Hard water test tube. Q. Do both test tubes have the same amount of foam?- No. The test tube containing detergent has more foam. Q. In which test tube is a curdy solid formed? -- In the test tube containing soap  Activity to demonstrate that Chlorophyll is necessary for Photosynthesis Activity 6.1  Activity 6.1 AASAN BHASHA MEI Samajhte hai: Take a potted plant with variegated leaves – for example, money plant or crotons. Keep the plant in a dark room for three days so that all the starch gets used up. Now keep the plant in sunlight for about six hours. Pluck a leaf from the plant. Mark the green areas in it and trace them on a sheet of paper Dip the leaf in boiling water for a few minutes. After this, immerse it in a beaker containing alcohol. Carefully place the above beaker in a water-bath and heat till the alcohol begins to boil Now dip the leaf in a dilute solution of iodine for a few minutes. Take out the leaf and rinse off the iodine solution Observe the colour of the leaf and compare this with the tracing of the leaf done in the beginning. Activity 6.1 Q. What happens to the colour of the leaf? What is the colour of the solution? Ans. The green leaf becomes colourless. On immersing green leaf in a alcohol, chlorophyll responsible for its green colour gets dissolves in alcohol. The colour of the alcohol solution turns green Q. What can you conclude about the presence of starch in various areas of the leaf? Ans. The green areas of leaf, which turns dark blue on dipping in iodine solution, indicate the presence of starch where as colorless part of leaf show no formation of starch. From this activity we can conclude that chlorophyll is essential for photosynthesis  Activity to show that amount of Carbon Dioxide (CO2), essentially affects the process and outcome of Photosynthesis Activity 6.2  Activity 6.2 AASAN BHASHA MEI Samajhte hai: Take two healthy potted plants which are nearly the same size. Keep them in a dark room for three days. Now place each plant on separate glass plates. Place a watch-glass containing potassium hydroxide by the side of one of the plants. The potassium hydroxide is used to absorb carbon dioxide. Cover both plants with separate bell-jars as shown in Fig.. Use Vaseline to seal the bottom of the jars to the glass plates so that the setup is air-tight. Keep the plants in sunlight for about two hours. Pluck a leaf from each plant and check for the presence of starch as in the above activity  Activity 6.2 Q. Do both the leaves show the presence of the same amount of starch? Ans. No, both the leaves do not show the presence of the same amount of starch, because in photosynthesis starch is produced using sunlight, chlorophyll and CO2. In first set up availability of CO2 will be less for making starch by the plant leaves, as potassium hydroxide (KOH ) absorb the CO2. In second plant setup, the leaves will have more amount of starch. Q. What can you conclude from this activity? Ans. From this activity, we can conclude that amount of Carbon Dioxide (CO2) , essentially affects the process and outcome of photosynthesis. Activity 8.2 Activity Observation: A white cottony mass appears on the surface of moist bread which turns black within few days. The white cottony mass is due to growth of bread mould (Rhizopus). The spores of fungus are present in the air. They settle on the moist bread and germinate to form white cottony mass of vegetative mycelium. The vegetative mycelium develops asexual sporangia which are black in colour. Each sporangium contains hundreds of minute black- coloured spores. These spores are dispersed in air to germinate on suitable substratum Activity 10.1 AASAN BHASHA MEI Samajhte hai: The curved surface of a shining spoon could be considered as a curved mirror. One Convex surface and other concave surface. Sp for answering the questions keep in mind the properties of both the spherical mirrors Activity 10.1 Q. Do you get the image? Is it smaller or larger? Ans. The image on the outer curved surface is smaller. Q. Move the spoon slowly away from your face. Observe the image. How does it change? Ans. The size of the image gradually decreases. Q. Reverse the spoon and repeat the activity. How does the image like now? Ans. The image at its concave side is real, inverted and diminished. Activity 10.1 Q. Compare the characteristics of the image on the two surfaces. The image at its concave side is real, inverted and diminished. If the spoon is moved away, the image becomes smaller. Image at the convex side is virtual, erect & diminished. If the spoon is moved away, the image becomes smaller. Activity 10.5 AASAN BHASHA MEI Samajhte hai: This activity is basically to find out the positions of the image formed by the convex mirrors, their nature, size etc Activity 10.5 Q. Observe the image of the pencil in the mirror. Is the image erect or inverted? Is it diminished or enlarged? Ans. Its image in the mirror is erect and diminished. Q. Move the pencil away from the mirror slowly. Does the image become smaller or larger? Ans. The image becomes smaller. Activity 10.5 Q. Repeat this Activity carefully. State whether the image will move closer to or farther away from the focus as the object is moved away from the mirror? Ans. The image moves closer to the focus.  Activity 13.2 AASAN BHASHA MEI Samajhte hai: The magnet exerts its influence in the region surrounding it. Therefore the iron filings experience a force. The force thus exerted makes iron filings to arrange in a pattern(Fig-13.2). The region surrounding a magnet, in which the force of the magnet can be detected, is said to have a magnetic field. The lines along which the iron filings align themselves represent magnetic field lines Activity 13.5 Activity 13.5 AASAN BHASHA MEI Samajhte hai: We shall first consider the pattern of the magnetic field around a straight conductor carrying current Q. What happens to the deflection of the compass needle placed at a given point if the current in the copper wire is changed? Ans. To see this, vary the current in the wire. We find that the deflection in the needle also changes. In fact, if the current is increased, the deflection also increases. It indicates that the magnitude of the magnetic field produced at a given point increases as the current through the wire increases. Activity 13.5 Q. What happens to the deflection of the needle if the compass is moved away from the copper wire but the current through the wire remains the same? Ans. To see this, now place the compass at a farther point from the conducting wire (say at point Q). Q. What change do you observe? Ans. We see that the deflection in the needle decreases. Thus the magnetic field produced by a given current in the conductor decreases as the distance from it increases. Activity 13.5 From Fig. 13.6, it can be noticed that the concentric circles representing the magnetic field around a current-carrying straight wire become larger and larger as we move away from it. Q. Does the direction of magnetic field lines get reversed if the direction of current through the straight copper wire is reversed? Ans. The direction of magnetic field lines is reversed if the direction of current through the copper wire is reversed. Thank you