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Activity Took a pinch of wheat flour and moisten it with water and add a few drops of iodine solution.

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Presentation on theme: "Activity Took a pinch of wheat flour and moisten it with water and add a few drops of iodine solution."— Presentation transcript:

1 Activity Took a pinch of wheat flour and moisten it with water and add a few drops of iodine solution.

2 Observation The contents turn bluish. Question Why it so happens?

3 Answer Wheat flour contains starch and starch gives blue colour with iodine.

4 Activity 1. Prepare water extract of a pinch of a chemical compound in a beaker. 2. Took a small quantity of the extract and added to it freshly prepared ferrous sulphate solution. 3. Now added conc. H 2 SO 4 by the sides of the test tube.

5 Observations A dark brown ring is seen in the middle of the solution. Question What could be the nature of the compound used?

6 Answer Answer It is a ring test of Nitrate.

7 Activity 1. Put lime water solution in a test tube 2. Blow air from the mouth through the solution with the help of a glass tube

8 Observation The solution turn milky. Question 1.Give the chemical name of the substance contained in the test tube. 2.State the reason of the contents of the tube turning milky.

9 Answer 1. The test tube contains Calcium hydroxide. 2. When air from the mouth is blown in the lime water, the Calcium hydroxide gets converted into Calcium carbonate by reacting the Carbon dioxide of the air from the mouth. The solution of Calcium carbonate is milky.

10 Activity 1. Gently lower an egg into a large glass of water. It will sink. 2. Remove the egg and put 10 table spoons of the salt in the water and dissolve it completely to make in the solution. 3. Put the egg in the solution.

11 Observations In the pure water the egg sinks whereas in the water with the salt, the egg floats. Questions Reason out the observation and define the phenomenon involved.

12 Answer 1. The being denser than pure water sinks. On the other hand, the addition of the salt makes the water denser than the egg, so the egg floats. 2. Density is the mass of a substance per unit volume i.e. d = M/V

13 Activity 1. Hold a postcard size paper between the thumb and the index finger in one hand. 2. Place the thumb & index finger of the other hand close to the other end of paper such that it does not touch the paper. 3. Release the paper and try to catch it with other hand. 4. Now ask your friend to catch the paper while you release it.

14 Observations While you release the paper with one hand you can easily catch it with the other hand. However, your friend can not. Question Explain the reason.

15 Answer When the same person holding the paper tries to catch it, it gets caught because the brain sends the impulse to the motor nerve to act on the muscles. On the other hand when the person who is to catch the paper is different from the one who release it, the eyes of former (who is to catch) send the message through the eyes to the brain which in turn sends the impulse to the motor nerve to act to catch the paper. This takes longer time than in the first situation.

16 Activity: Take a test tube and fill 3/4 th of it with water. Hold the tube in an inclined position and heat the upper part of the water in it.

17 Observation: The water at the upper level starts boiling. However, there is no difficulty in holding the tube from the lower end. Question: Why the lower end does not get hot?

18 Answer: When water is heated even to the extent of boiling, it gets converted into steam that being lighter in weight, escapes out from the tube. So the water at the lower part of the tube remains unaffected by the heat

19 Activity Take tow eggs – one fresh/raw and other hard boiled. Give spin to both the eggs simultaneously on a horizontal plane surface.

20 Observation One egg spins uniformly and the other vaguely. Question 1. Distinguish between the raw and the hard boiled egg. 2. Give basis for your inference.

21 Answer 1. The egg that spins well is hard boiled while the other that spins vaguely is the raw one. 2. The raw egg does not spin well because the friction between the egg shell and the surface of the base gets impaired by the friction between the contents of the egg and the shell.

22 Activity 1. Take a small bucket filled half with water. 2. Put the bucket in circular motion with at a fast speed.

23 Observation The water from the bucket does not fall even when it is inverted at the top of the round. Question Why water does not fall?

24 Answer Water doesn’t fall because of the centrifugal force. It maintains the maximum distance between the object moving speedily in a circular path and the center of circle of rotation. The more the speed of rotation, the more will be the centrifugal force.

25 Activity 1. Take a cup and place a coin in it. 2. Look at it and starts moving away from it till the coin becomes out of sight. 3. Request some one to add water into the cup slowly till it is nearly filled.

26 Observation You can again see the coin from the position from it was not visible earlier. Question What is the reason of reappearance of this coin?

27 Answer The coin is visible in the cup because the light travels straight from the coin into your eyes but when you move away, the wall of he cup obstructs the path of light. When the cup is filled with water, the ray of light traveling through the medium of water gets refracted when it enters the medium of air. The refracted image of he coin is thus, visible.

28 Activity 1. Take a thick paper and make its pot and fill about half with water. 2. Place it over a wire gauge on a tripod stand and heat it with flame.

29 Observation Water gets warm up without burning the paper. Question Why the paper does not burn.

30 Answer In an uncovered pot one can warm water only up to the boiling point i.e. 100ºC. Water having great heat capacity, absorbs the papers’ extra heat and prevents it from warming more than 100ºC, i.e. to a point where it could burst into flame.

31 Activity Take a bar magnet near to the iron fillings.

32 Observation : The magnet attracts the iron fillings. Question: Why does it attract?

33 Answer: In the magnet the half field spins of the atoms give us the domain of a tiny magnet, in bar magnet, these tiny magnets are arranged in a particular order that attracts the iron fillings to make the filling in the same order

34 Activity Squeeze some lemon juice on a piece of chalk.

35 Observation Fizzes appear on the chalk surface. Question Why does it so happen?

36 Answer Fizzes appear due to production of gas. Calcium carbonate of chalk reacts with weak acid and produces CO 2

37 Activity Take two bar magnets. Bring them together

38 Observation: They either attract or repel each other. Question: Why it is so?

39 Answer: Magnetic poles connect the magnets by their respective field lines. When the same pole come closer, the field lines repel each other that is why the like poles repel. While opposite poles take field lines from one pole to terminate to another pole. Therefore, they attract each other.

40 Activity Take a flask and cover its mouth with a balloon. Heat the flask.

41 Observation The balloon inflates Question Why it inflates?

42 Answer When the flask is heated, the air inside it expands and becomes lighter and needs more space. It goes into the balloon which inflates.

43 Activity 1. Take two beakers of equal sizes. 2. Pour cold water in the one and the hot water in the other. 3. Put two drops of the dark ink in each beaker simultaneously.

44 Observation In the beaker containing hot water in the ink dissolves readily than in the one having cold water. Question Reason out the observations and define the phenomenon behind this.

45 Answer The reason behind this observation is the process of diffusion. It depends upon the concentration and nature of the solute and temperature. In the hot water due to high temperature, the kinetic energy of the solute molecules is more, thereby resulting in the fast dissolving of ink in hot water. Diffusion is the movement of the solute from higher conc. to lower conc.

46 Activity Put a stamp on the table and place a glass beaker containing water over it. Cover it with saucer.

47 Observation The stamp disappears irrespective of the direction from where we try to see. Question Why does stamp disappear?

48 Answer The principle of Refraction governs the phenomenon involved. The incident light while entering from the rarer to the denser medium bends towards the normal, and moves away from normal when it comes from denser to rarer medium. When we look from the side, the angles formed are such that the stamp becomes invisible.

49 Activity Took a glass of water. Pour a drop of honey from two different samples

50 Observation One of the samples shows a fibrous streak of honey while the other dissolves without forming the honey thread. Question What inference is drawn?

51 Answer The pure honey has a higher viscosity and takes more time in dissolution, while the honey adulterated with sugar dissolves easily because of water content contained in sugar solution.

52 Activity 1. Take a pencil torch and a laser pointer. 2. Switch these on simultaneously and throw the light on wall/screen.

53 Observation The torch light will show a wider spot, while the laser light will show a narrow spot. Question What is the principle behind this phenomenon?

54 Answer In case of Laser, the quanta of light photon get aligned by the stimulation of photons and we obtain monochromatic and coherent beam while the light emitted from the torch neither monochromatic and nor coherent.

55 Activity 1. Tie a metal coat hanger in the centre with a piece of rope. 2. Tie one end of the rope three or four times around your left finger and other end to your right finger. 3. Put the ends of your fingers into your ears. 4. Strike the coat-hanger against a chair.

56 Observation: You will hear some beautiful music. Question Why it is so?

57 Answer The music is heard because the coat-hanger vibrates. The rope and your fingers bring the sound waves to your ears

58 Activity Take a pinch of material in a test tube and add Fehling solution A and B in equal amounts. Heat the contents.

59 Observation Formation of Red precipitates. Question Tell the chemical nature of the compound.

60 Answer Presence of Reducing sugar (Free or potentially free aldehyde or ketone group). Reducing sugar give red coloured cuprous oxide in alkaline medium.

61 Activity 1. Take some amount of sodium carbonate in a balloon and acetic acid in a test tube. 2.Cover the mouth of test tube with the balloon and invert the contents from the balloon.

62 Observation The balloon increases in volume. Questions Why it so happens? Give the reaction for the observed phenomena.

63 Answer The balloon increases in volume due to the upward movement of the gas formed in the test tube. The sodium carbonate reacts with acetic acid and produces CO2 which moves up and causes an increase in volume of balloon. 2CH 3 COOH + Na 2 CO 3 2CH 3 COONa + CO 2 + H 2 O

64 Activity 1. Shake 0.5 gm of compound with 1-2 ml of water. 2. Add few drops of 10% α-Naphthol. 3. Add conc. H 2 SO 4 along the side of the tube.

65 Observation Formation of purple coloured ring on the junction of two liquids. Question What is the functional group of the compound?

66 Answer Carbohydrates are converted to furfural which reacts with α- Naphthol to give purple colour.

67 Activity Take 1-2 ml of compound in a test tube. Add Bromine water to the test tube.

68 Observation Formation of white precipitates. Question What is the functional group of the compound.

69 Answer : Phenol White precipitates are formed due to the formation of Tribromophenol.

70 Activity Take a beaker with water in it and put some drops of fountain pen ink.

71 Observation The water in the beaker will slowly attains the colour of the ink. Question Which phenomenon is governing this? Explain it.

72 Answer Process of diffusion governs it. It states that the solute molecules will tend to move from a region of higher concentration in an open medium till the equilibrium is achieved.

73 Activity Take Ammonium dichromate in a watch glass. Add few drops of ethyl alcohol to moisten it. Ignite it.

74 Observation After burning, an eruption like a volcano is seen Question Why does it happens so?

75 Answer It is a highly exothermic reaction and oxide in the form of ash that as result forms a heap like that of a volcano.

76 Activity Dip a glass rod in a solution of an organic compound and bring it on to the flame.

77 Observation It gives smoky flame. Question What category of organic compound it was?

78 Answer Aromatic compounds give smoky flame.

79 Activity Dip a glass rod in a solution of an organic compound and bring it on to the flame.

80 Observation No change in the could be seen. Question What category of organic compound it was?

81 Answer Aliphatic compounds do not give smoky flame.

82 Activity Squeeze some lemon juice on a piece of chalk.

83 Observation Fizzes appear on the chalk surface. Question Why does it so happen?

84 Answer Fizzes appear due to production of gas. Calcium carbonate of chalk reacts with weak acid and produces CO 2

85 Activity Place crystals of Potassium permanganate in a dish and add a few drops of Glycerin. Put a few paper clippings over it and wait.

86 Observation After some time smoke followed by flame is seen. Question Why does the paper burn without any external help?

87 Answer Glycerin in contact with Potassium permanganate, results in a highly exothermic reaction so strong that the paper gets ignited.

88 Activity 1.Take three different types of soils. 2. Put 20 g of each soil type in 50 ml of water and make a slurry. 3. Dip a strip of the red/blue litmus paper in the slurry.

89 Observations In one soil the blue litmus paper turns red, whereas in the other red turns blue while in the third one it remains unchanged. Questions 1.Why the litmus paper changes colour and why not? 2.Name the phenomenon responsible for the observed change and define.

90 Answer 1. In one case where the litmus turns Red, the soil is Acidic; in the other where litmus turns Blue, the soil is alkaline; while the one where litmus changes no colour, the soil is neutral. 2. The phenomenon responsible is pH. Ph is the negative logarithmic of the H + ion concentration.

91 Activity 1. Three beakers are filled with water. 2. Measure the purity of each and arrange the samples accordingly using conductivity of each.

92 Question Which water is more pure and why.

93 Answer The water with least conductivity is more pure. Because less conductivity means lesser number of dissolved ions and so lesser flow of ions / current

94 Activity Take few drops of an organic compound in water and add 1-2 drops of neutral ferric chloride.

95 Observation Appearance of blue colour. Question What is the functional group of the compound?

96 Answer : Phenolic group Neutral ferric chloride reacts with phenolic compounds to form ferric phenoxides, which have characteristics colours depending upon the nature of the phenolic compounds. Here it was p-Cresol.

97 Activity Hold a piece of paper horizontally close to your mouth/lips. Blow across the top of the paper as it hangs down from hands in front of lips.

98 Observation The paper will respond by moving up, toward the stream of moving air. It would seem the paper would move away from the stream of air, but it moves toward the stream of air. Question Name the principle involved in the process

99 Answer Bernoulli's Principle

100 Activity Take a lemon; insert a copper wire and carbon rod in it. Tie both the carbon and the copper wire to cathode and anode of the Galvanometer.

101 Observation Galvanometer shows deflection. Question Why does it deflect?

102 Answer Lemon contains citric acid which acts as electrolyte. Copper and Carbon act as electrodes. So, electrons flow from cathode to anode and as a result current flows. Thus Galvanometer shows deflection.

103 Activity 1. Sit up-right/straight in your chair with legs straight down with legs bending at knees at approx 90 o angle and the feet together. 2. Without changing the place of your feet and without bending forward try to get up.

104 Observation You can not get up unless you bend forward or take or move your feet under the chair. Question Why you could not get up without bending forward or changing the position of your feet.

105 Answer For equilibrium, we know that the line perpendicular to the centre of Gravity must fall through its base. By bending forward, the position of the centre of gravity is changed so that it falls through the base of the body. Till it is done the equilibrium which is essential for stability is not achieved and thus one can not get up unless one bends forward. Similarly by changing the position of the feet and bringing them under the chair, the base of the body is moved so that the line falling from the centre of the body falls through it.

106 Activity Take a glass full of water. Take a needle on a piece of blotting paper and place it gently over the water surface.

107 Observation Blotting paper soaks water and sinks down but the needle keeps floating. Question What do you observe and why is it so?

108 Answer It is because of surface tension. The molecules of water adhere together due to surface tension forming a thin membrane on surface.


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