Government of Tamil NaduREFRESHER COURSE MODULE 2021 - 2022 9 SCIENCEDepartment of School Education
TABLE OF CONTENTSS.NO TOPIC PAGE NO. 1. Measurement 1 2. Force and pressure 4 3. Light 8 4. Heat 13 5. Electricity 19 6. Sound 22 7. Magnetism 25 8. Universe and Space 28 9. Matter around us 30 10. Changes around us 33 11. Air 37 12. Atomic structure 41 13. Water 45 14. Acids and Bases 49 15. Chemistry in Everyday life. 51 16. Micro organisms 55 17. Plant kingdom 61 18. Organization of life 66 iii
1 MEASUREMENTLEARNING OUTCOMES Uses of scientific conventions, symbols and equations to represent various quantities, elements and unit such as fundamental quantities and their units. Analyses and interprets graphs and diagrams such as system of units and importance of SI system. Describes scientific discoveries and inventions such as the different kinds of clocks. Measures physical quantities using appropriate apparatus, instruments, and devices such as Thermometer, Ammeter, Photometer.MOTIVATION 1. How will you buy vegetables at shop? What measurement is used? 2. How far is your house located from your school? 3. What is the duration of your science period? 4. Explain the model of the clock in your home?TEACHER ACTIVITY - 1 Measurement is the base of all scientific experiments and plays a vital role in our daily life. Seven basic quantities and their unit will be clearly explained to get more accuracy and precision. Fundamental and derived quantities will be explained. Matching cards can be shown for better understanding. All other physical quantities which can be obtained by multiplying, dividing or by mathematically combining the fundamental quantities are known as derived quantities. Matching the correct pair of the derived quantities and its units using the spiral cardTEACHER ACTIVITY – 2 1. Explains the clocks which are used to measure time intervals. 2. Recalls the sand clock, water clock and sun dial that were used in ancient days. 3. Different types of clocks used in modern days to get accuracy will be shown in album by the teacher. 4. Types of clock based on display - Analog clocks, Digital clocks 5. Types of clock based on working mechanism - Quartz clock, Atomic clock 1
TEACHER ACTIVITY – 3 Flow of electric charges, in a particular direction is known as ‘electric current’. The magnitude of electric current is the amount of electric charge flowing through a conductor in one second. Electric current = Amount of electric charge × time I = Q t. Electric charge is measured in coulomb. The SI unit of electric current is ampere and it is denoted as A. Teacher connects a battery, an ammeter and a lamp in series as shown in the figure. Ask students to note the ammeter reading which is the amount of current flowing in the circuit. Ammeter A Ba ry Lamp 150 200 100 25 50 0 300 Ammeter 0 – +STUDENTS ACTIVITY – 1 1. Take a round card board. 2. Cut the numbers from 1 to 12 from the monthly calendar. 3. Paste the numbers on the round cardboard at regular intervals. 4. Make three hands (seconds hand, minutes hand, hours hand) using a thin chart paper. 5. Fix the three hands in the round card board using drawing (or) clutch pin. 6. Rotate the pin and find the time.STUDENTS ACTIVITY – 2 Write the measurements of the following in SI unit. 1. Length - The length of a room in your home or school 2. Mass - The amount of potato bought from the shop 3. Time - The time taken to reach the school from your house 4. Electric Current - The amount of current passing through a bulb 5. Temperature - Today’s temperature of your district head quarters 2
EVALUATIONI. CHOOSE THE BEST ANSWER1. The amount of electric charges flowing through a conductor in one second is _______ (a) Electric Current (b) Resistance (c) Electric potential2. The SI unit of temperature is ______________ (a) Celsius (b) Fahrenheit (c) Kelvin3. The SI unit of luminous intensity is________________ (a) mole (b) Candela (c) AmpereII. FILL IN THE BLANKS:1. The degree of hotness or coldness of a substance is __________________2. The SI unit of mass is _____________________3. One mole of a substance contains ___________________ atoms or molecules.4. _______________ clock uses the periodic vibrations accruing within the atom.5. Luminous intensity is measured by ____________________6. Heat energy given to a substance will ______________________________ its temperature.III. ANSWER THE FOLLOWING:1. Electric current is measured by an instrument called ammeter. Is it true or false?2. Atomic clocks are used in GPS devices. Is it true or false?3. What are the units of temperature?4. Name the three hands used to show time in analog clock.5. How will you calculate Indian standard time (IST)?6. How many times will the minute hand rotate in one hour?7. How many base quantities are in SI system?8. Name the device used to measure the temperature.9. What is the SI unit of Luminous intensity? 3
2 FORCE AND PRESSURELEARNING OUTCOMES Explains the process and phenomenon – knows the definition of velocity, displacement, and acceleration. Conducts simple investigations to seek answers to queries – Applies learning of scientific concepts in day-to-day life - Pressure, Surface tension, pascal’s law Friction. Differentiates thrust and pressure.TEACHER ACTIVITY:1 Teacher explains force. Force is defined as an external agency which changes or tends to change the state of rest or the state of uniform motion of a body or the direction of a moving body or the shape of a body. Force is a vector quantity, which has magnitude and direction. It is measured by a unit called ‘newton’ (N). Teacher explains the effects of force to students through some appropriate examples. Fix sharp pins on a wooden board in rows and columns. Take a big blown up balloon. Place it gently over the pins and place a small book on the top of the balloon. Will the balloon burst? Will the pins prick the balloon? Pressure exerted by a force depends on the magnitude of the force and the area of contact. The effect of force can be measured using a physical quantity called pressure. It can be defined as the amount of force or thrust acting perpendicularly on a surface of area of one square meter of a body. Pressure = Thrust (or) Force/ Area ie., P = F/ A. The SI unit of pressure is pascal. 4
TEACHER ACTIVITY:2 Teacher demonstrates appropriate experiments to show how force exerted by air as well as liquids Force exerted by liquids Spouting Nozzle Take a plastic bottle. Punch three holes can on its side in the same direction, but Pressure Low pressure jet at different heights. Now pour some of water water into it and let it flow through increases with the holes. Observe the flow of water. depth Water from the lowest hole comes out high pressure jet with the greatest force and the water from the topmost hole comes out with Water the least force. Force exerted by air Take a conical flask and a well boiled egg. After removing its shell, place the egg on the mouth of the flask. It will not enter the flask. Now take a piece of paper. Burn it and drop it inside the flask. Wait for a few seconds to burn fully. Now, keep the egg on the mouth of the flask. Wait for a few minutes. What do you observe?TEACHER ACTIVITY:3 Teacher explains Pascal law, surface tension and Friction with real life examples.STUDENT ACTIVITY:1 – List out the actions where we use force in our daily life.STUDENT ACTIVITY:2 – Force exerted by liquids 1. Take a plastic bottle. Punch three holes on its sides at the same height from its base. Now, pour some water into it and let it flow through the holes. Observe the flow of the water. The water comes out from all the holes with the same force and falls on the ground at the same distance from the bottle. 5
2. Take a glass tube that is open at both ends. Fix a rubber balloon at the lower end of the tube. Pour some water into the tube and observe the balloon. Now, pour some more water into the balloon and again observe the balloon. The balloon starts bulging outwards.STUDENT ACTIVITY:3 – Pascal’s law Take a rubber ball and fill it with water. Make tiny holes on its surface with a pin at different points. Press anywhere on the ball. What do you observe?STUDENT ACTIVITY:4 (GROUP ACTIVITY) Observe the devices, gadgets or things around you. List out the types of friction involved in each device. How would you minimise the friction? Record your observations and discuss your results with your classmates. EVALUATIONI. CHOOSE THE BEST ANSWER1. If we apply force against the direction of motion of the body, then the body will a. stop moving b. move with an increased speed c. move with a decreased speed d. move in a different direction2. Pressure exerted by a liquid is increased by a. the density of the liquid b. the height of the liquid column c. Both a and b d. None of the above 6
3. Unit of pressure is a. Pascal b. Nm–2 c. Poise d. Both a and b4. Pascal’s law is used in a. hydraulic lift c. brake system b. pressing heavy bundles d. All the aboveII. FILL IN THE BLANKS:1. The pressure of a liquid column __________ with the depth of the column2. A simple barometer was first constructed by __________.3. Force acting on a given area is called _________________.4. A body will ___________ (sink/float) if the weight of the body is greater than the buoyant force.III. COMPLETE THE ANALOGY:1. Knot in a thread: _____ friction | Ball bearing: _____ friction2. Downward force: Weight: |Upward force offered by liquid : _____IV. ANSWER THE FOLLOWING:1. Give two examples to verify that a force changes the shape of a body2. Give two examples to verify that a force tends to change the static condition of a body3. Name two instruments which help to measure the pressure of a fluid.4. Why is it not advisable to use a fountain pen while travelling in an aeroplane? 7
3 LIGHTLEARNING OUTCOMES: Explains processes and phenomenon with causes. (e. g) formation of multiple images reflection. Measures angles of incidence and reflection. Constructs models using materials from surroundings and explains their working. (e. g) periscope. Describes scientific discoveries and inventions such as spherical mirrors like concave and convex mirror. Applies scientific concepts in daily life and solving problems such as application of spherical mirrors. Designs models using eco-friendly resources such as kaleidoscope and periscope.MOTIVATION 1. What is the purpose of using rear view mirrors in vehicles? 2. How do the torches direct the light to a long distance? 3. What do you observe when the sunlight falls on a mirror is focused on a wall? 4. What type of image is formed in a plane mirror?TEACHER ACTIVITY - 1: Teacher explains the classification of mirrors with the following figure. Mirrors Plane mirrors Curved mirrors Spherical mirror Cylindrical mirror Parabolic mirror Ellipsoid mirror 8
TEACHER ACTIVITY – 2 (SPHERICAL, CONCAVE AND CONVEX MIRROR) Terms related to spherical mirrors and the size, nature and the distance of the images formed in the mirrors will be explained by the activity using convex and concave mirror. Uses of these mirrors will be explained by the teacher with the help of real life examples. 1. Centre of Curvature :The Centre of the sphere from which the mirror is made 2. Radius of curvature :The distance between the centre of the sphere and the vertex 3. Pole : The geometric centre of the spherical mirror 4. Principal Axis :The line joining the pole of the mirror and it’s centre of curvature 5. Principal Focus :Converging point of the reflected rays in a concave mirror or diverging point of the reflected rays in a convex mirror. 6. Focal length : The distance between the pole and the principal focus. Concave mirror Convex mirror 9
TEACHER ACTIVITY – 3(MULTIPLE REFLECTION) 1. Take two plane mirrors and keep them perpendicular to each other. 2. A small object (Ball, Toy, Button) is placed between them. 3. Three images of the object will be seen. 4. Then the angle between the plane mirror are kept as 600, 450 and 300 and the numbers of images formation are noted. 5. The number of images formed can be calculated by the formula n-1.TEACHER ACTIVITY – 4 (DISPERSION) 1. Place a prism on a table and keep a white screen near it. 2. Now, with the help of a torch, allow white light to pass through the prism. What do you see? 3. You can observe that white light splits into seven colored light rays namely, violet, indigo, blue, green, yellow, orange and red (VIBGYOR) on the screen. 4. Now, place another prism in its inverted position, between the first prism and the screen. Now, what do you observe on the screen?STUDENT ACTIVITY – 1 (TYPES OF SPHERICAL MIRROR) 1. Take a curved silver spoon and see your image. 2. Now turn it and note down the image formed. 3. Compare and note the differences between them. 4. Move the spoon nearer and farther to you and note the differences you noticed.STUDENT ACTIVITY – 2 (MULTIPLE REFLECTION - KALAIDOSCOPE) 1. Take three equal sized plane mirror strips. 2. Arrange them in such a way that, they form an equilateral triangle. 3. Cover the sides and the bottom of the mirrors with a chart paper. 4. Put some coloured beads of glass pieces inside it. 5. Cover the top portion with a chart paper and make a small hole in it. 6. Cover the entire piece with coloured paper to make it attractive. 7. Now rotate it and see the beautiful patterns through the opening. 10
STUDENT ACTIVITY 3 1. Take a stainless steel spoon. Bring the outer side of the spoon near your face and look into it. Do you see your image in it. Is this image different from what you see in a plane mirror? Is this image erect? Is the size of the image the same, smaller or larger? 2. Now look at your image using the inner side of the spoon. This time you may find that your image is erect and larger in size. If you increase the distance of the spoon from your face, you may see your image inverted. You can also compare the image of your pen or pencil instead of your face. 3. The curved shining surface of a spoon acts as a mirror. The most common example of a curved mirror is a spherical mirror. If the reflecting surface of a spherical mirror is concave, it is called a concave mirror. If the reflecting surface is convex, then it is convex mirror.EVALUATIONI. ANSWER IN ONE WORD:1. The spherical mirror with a reflecting surface curved outward is called a) convex mirror b) concave mirror c) curved mirror2. The spherical mirror used as a rear view mirror in the vechicle is ___________. a) concave mirror b) convex mirror c) Plane mirror3. The mirror used in solar cooker is ___________. a) convex mirror b) concave mirror c) Plane mirror4. If the image and object size is the same, The object is placed at ___________. a) at F b) at C c) infinity 11
5. The mirrors used in narrow and delicate curved road are___________. a) Plane mirror b) convex mirror c) concave mirror6. Kalaidascope works on the principle of ___________. a) Regular reflection b) Irregular reflection c) Multiple reflectionII. FILL IN THE BLANKS1. Image formed by a convex mirror is always ___________ in size.2. The distance from the pole to the focus is called ___________.3. Nature of the images formed by a convex mirror is ___________.4 Two mirror are paralled to each other, then the numberof images formed is ___________.5. The mirror used by the ophthalmologist to examine the eye is ___________.III. ANSWER THE FOLLOWING1. The centre of the sphere from which the convex mirror is made is called it’s pole. Say True or False2. What is the formula for calculating the images formed between plane mirrors?3. Differentiate : Concave mirror and Convex mirror.4. What are the types of Reflections.5. Define focal length.6. Give any two applications of a concave and convex mirror.7. State the laws of reflection.8. Define the refractive index of a medium.9. Take a plane mirror and focus the light coming from the Sun on a wall. Can you see a bright spot on the wall? How does it occur? It is because the light rays falling on the mirror are bounced onto the wall. Can you produce the same bright spot with the help of any other object having a rough surface?10. List out various convex and concave mirrors used in daily life. 12
4 HEATLEARNING OUTCOMES plans and conducts investigations or experiments to arrive at and verify the facts, principles, phenomena or to seek answers to queries on their own, what is the effect of heat on the state of substances? Etc., draws labelled diagrams, flow charts, concept maps, graphs, such as, time Vs increase in temperature, interprets graph. applies scientific concepts in daily life and solving problems, such as, a thermostat is a device which maintains the temperature of a place or object constant., The thermos flask (Vacuum flask) is an insulating storage vessel that keeps its content hotter or cooler than the surroundings for a longer time etc.INTRODUCTION 1. What is Temperature? 2. What is the SI unit of heat energy? 3. What are three scales to measure the temperature? 4. To understand the effects of heat energy (i) Expansion (ii) Increase in temperature (iii) Change in state 5. To understand the Transfer of Heat. When a object is heated the heat tranfered in three ways. • Conduction • Convection • Radiation. 13
TEACHER ACTIVITY – 1: Teacher introduces the lesson with the below found concept map. Heat ects of Heat Transfer of Heat Calorimetry Application • Conduction • Temperature • Calorimeter • Expansion • Unit of Heat • Increase in • Convection • Heat capacity temperature • Sp at • Change in state • Radiation capacityTEACHER ACTIVITY – 2: Effects of Heat - Expansion Take a cup of water and note it’s temperature. Heat the water for few minutes and note the temperature again. Now the mercury level is increased. There as on is the heat energy is transferred from water to thermometer and the mercury is expanded due to heat.TEACHER ACTIVITY: 3 Transfer of Heat – Conduction 1 2 3 4 14
Step 1 – Begin by positioning 3 spoons in a small glass bowlStep 2 – Place a small pat of butter at the top of each spoon.Step 3 – Put a bead in each pat of butter.Step 4 – C arefully pour hot boiling water into the bowl until it is almost completely full. Be careful not to allow the spoons to fall into the bowl.Step 5 – W atch carefully to see what happens to the beads. Write down your observations. Did all the beads behave the same? Do you know why? Find out the answer in the how does this experiment work section below.Conclusion: In solid substances such as silver spoon, atoms are arranged very closely. Hot water molecules which are vibrating transfer the heat energy to the atoms in the spoon and make them vibrate. Those atoms make other atoms to vibrate and thus heat is transferred to the other end of the spoon. From this we can define conduction as the process of heat transfer in solids from the region of higher temperature to the region of lower temperature without the actual movement of atoms or molecules.Conduction in daily life We cook food in vessels made up of metals. When the vessel is heated, heat is transferred from the metal to the food. When we iron dresses, heat is transferred from the iron box to the cloth. 15
STUDENT ACTIVITY -1:Heat Energy Causes - Increase in temperature Take a cup of water and note its temperature with the help of Thermometer. Heat the water for few minutes and note the temperature again. & ask to find any increase in it? When the water is heated, water molecules receive heat energy. This heat energy increases the kinetic energy of the molecules. When the molecules receive more energy, the temperature of the water increases. This shows that heat energy causes increase in temperature.STUDENT ACTIVITY – 2:Draw a Graph; Time Vs Increase in Temperature Step 1: Take a vessel. Pour water into it. Heat the water slowly. Step 2: Note the temperature with the help of thermometer in every five minutes. Step 3: Tabulate the readings of time and temperature up to 1000c Step 4: Plot the graph taking time in X axis and temperature in Y axis Tabulation (Sec) (0c) TIME TEMPERATURE 0-5 35 10 45 15 60 20 75 25 90 30 100Changes of state liquid to gas Y-Temperature 120 100 80 60 40 20 0 0 5 10 15 20 25 30 35 X =Time in (Sec) 16
EVALUATIONI FILL IN THE BLANKS:1. The measure of degree of hotness or coldness of the body is called--------2. In a solid, heat is transferred from mainly by the process of ------------------3. If two bodies A& B 50*C come in contact with each other. The heat will flow------------- (a) A to B (b) B to A (c) No where4. On touching a lump of ice, we feel cold. The heat will flow from------ (a) Hand to ice (b) ice to hand (c) None5. Conduction is only Possible when the bodies in contact have temperature difference---- (a) True (b) FalseII. CHOOSE THE CORRECT ANSWER1. Heat is a form of ________. a. electrical energy b. gravitational energy c. thermal energy d. None of these2. If you apply some heat energy to a substance, which of the following can take place in it? a. Expansion b. Increase in temperature c. Change of state d. All the above.3. Conduction is the way of heat transfer which takes place in a ____________. a. Solid b) Liquid c) Gas d) All the above 17
4. The SI unit of temperature is ____________. a. Farenheit b) Joule c) Celcius d) Kelvin5. What is the name of the method conduction heat from one molecule to another without the actual movement of molecules. a. Radiation b) Conduction c) Convection d) b and cIII. MATCH THE FOLLOWING:1. a) Liquid - Conduction b) Gas to liquid - Convection c) Solid to gas - Radiation d) Vacuum - Sublimation e) Solid - CondensationIV. ANSWER THE FOLLOWING:1. What are the applications of conduction in our daily life?2. What are the effects of heat?3. Name the types of heat transfer.4. What is conduction?5. Write a note on convection6. Explain the working of thermo flask 18
5 ELECTRICITYLEARNING OUTCOMES Explains the process and phenomena such as the concept of electric charge and current. Plans and conducts investigations or experiments to arrive at and verify the facts, principles, phenomena or to seek answers to queries on their own such as different types of electric circuit. Relates processes and phenomena with causes and effects, such as the effect of electric current. Draws conclusion such as the application of electricity.MOTIVATION Asking questions to motivate the students. 1. What are elements made up of ? 2. What are the fundamental particles of Atom? 3. What is the charge of electron? 4. What is the charge of proton?TEACHER ACTIVITY - 1 To make a simple circuit which consists of Battery, Wire, Switch, Lamp. To explain the path through which electrons flow from one terminal to another terminal of the source, is called electric circuit. Explain electric current and electric charge.TEACHER ACTIVITY – 2 Using blackboard and chart, draw and explain the series and parallel connection of circuits. Motivates the students to form circuits and explain their differences.TEACHER ACTIVITY – 3 Take two pieces of wire, an LED light and battery and make a simple electric circuit. Take some water in a glass and put the wire in the water as shown in figure. Does the LED bulb glow? What do you understand from this? Using this experiment, explains the chemical effect of electric current. This activity shows that liquids also conduct electricity.TEACHER ACTIVITY – 4 In your house, you can feel the heat of fan and light after you use it for same time. Using this real life experience you can explain the effect of heat by the current. 19
STUDENT ACTIVITYACTIVITY – 1 Ask the students to form two groups and ask them to make series and parallel connection of electric circuits.ACTIVITY – 2 List out the appliances which works by heat through electric current. EVALUATIONI. CHOOSE THE BEST ANSWER:1. When an ebonite rod is rubbed with fur, the charge acquired by the fur is ___________ (a) Negative (b) Positive (c) Partly positive and partly negative (c) None of these2. Which of the following should a simple circuit have? (a) Energy Source, Battery, Load. (b) Energy Source, Wire, Switch (c) Energy Source, Wire, Load (d) Battery, Wire, Switch3. Fuse is __________________. (a) a switch (b) a wire with low resistance (c) a wire with high resistance (d) a protective device4. The process of depositing a layer of one metal over the surface of another metal by passing electric current is called _____________. (a) Electrolysis (b) Electroplating (c) Chemical effect of current (d) Heating effect of current 20
5. In which circuit the voltage will be the same across each component? (a) Series Circuit (b) Parallel Circuit (c) Simple Circuit (d) None of theseII. FILL IN THE BLANKS:-1. The body which has lost electrons becomes___________________.2. A device that stores electricity from chemical cells is ____________________.3. A fuse (consists) has ___________________________,______________________.4. ____________________________ has a thin metallic filament that melts and breaks the connection when the circuit is overheated.5. Three bulbs are connected end to end from the battery. This connection is called ________ ___________________________.III. TRUE OR FALSE:-1. In this series circuit, charges (electrons) from the battery have only one path to travel.2. In parallel circuit, current remains the same in all components.3. Water can conduct electricity.4. A charged body induces an opposite charge on an uncharged body when they are brought near.5. If one component breaks down, the whole circuit will function.IV. MATHCH THE FOLLOWING:- 1. a) Circuit - A device that stores electricity from chemical cells b) C hemical effect of electric - The path through which electric current flows current c) Heating effect of electric - Electro plating current d) Unit of electric pressure - Electric cookers e) Battery - Volt 21
6 SOUND Relates processes and phenomena with causes and effects such as the production of sound. Draws labeled diagrams, flow charts, concept maps, graphs such as the propagation of sound in a medium. Classifies materials, objects, organisms, phenomena and processes, based on properties or characteristics such as properties of sound. Relates process and phenomena with causes and effects such as noise pollution and the ways to control etc.MOTIVATION: 1. Have you ever gone to an Orchestra? 2. Name some Musical Instruments that you have seen? 3. Can you hear sound in a closed glass room? 4. How do bats and whales get their food? 5. Have you ever heard the thunder and seen the lightning? 6. Have you cracked a cracker? 7. What are the differences between music and noise? 8. Mention the sources of noise? 9. What are the hazards of noise pollution? 10. Mention few measures to be taken to reduce the effect of noise pollution. We can ask questions on the particular topic, students will give various answers. Through these answers, we can introduce the topic. 22
TEACHER ACTIVITY – 1: Take a bell jar and Mobile phone Switch on the music in the mobile phone and place it in the jar. Now pump out the air from the bell jar using a vacuum pump. As more and more air is removed from the jar, the sound from the mobile phone becomes feebler and finally very faint.TEACHER ACTIVITY – 2: Take a metal dish and pour some water in it. Strike it at its edge with a spoon. Do you hear any sound? Again, strike the dish and touch it. Can you feel the dish vibrating? Look at the surface of water. Do you see any movement on the water surface? Now hold the dish with your hands. What change do you observe on the surface of water?STUDENT ACTIVITY: Take the tray of an empty match box and stretch a rubber band around it along its length. Then pluck the stretched rubber band with your index finger. What do you observe ? Do you hear any sound? EVALUATION1. Sound waves travel very fast in . a) Air b) Metal c) Vacuum d) Liquids2. The amplitude of the sound wave decides its . a) Speed b) Pitch c) Loudness d) Frequency3. Find the odd one out. a) Harmonium b) Flute c) Nadaswaram d) Violin4. Noise is produced by . a) Vibrations with high frequency b) Regular vibrations c) Regular and Periodic vibrations d) Irregular and non-Periodic vibrations5. The range of audible frequency for the human ear is . a) 2Hz to 2000Hz b) 20Hz to 2000Hz c) 20Hz to 20000Hz d) 200Hz to 20000Hz6. Which of the following are the characteristics of vibrations ? i) Frequency ii) Time Period iii) Pitch iv) Loudness a) i and ii b) ii and iii c) iii and iv d) i and iv 23
7. What king of musical instrument is a sitar? a) String instrument b) Percussion instrument c) Wind instrument d) None of these8. If amplitude and frequency of sound wave are increased, which of the following is true? a. Loudness increases and pitch is higher b. Loudness increases and pitch is unchanged c. Loudness increases and pitch is lower d. Loudness decreases and pitch is lower9. Which of the following may be caused by noise? a) Irritation b) Stress c) Nervousness d) All the above.10. Sound is produced by _______.11. The vibrations of a simple pendulum are also known as _______.12. Sound travels in the form of _______.13. High frequency sounds that cannot be heard by you are called _______.14. Pitch of a sound depends on the _____ vibration.15. If the thickness of a vibrating string is increased, its pitch ______.16. The speed of a wave is the distance travelled by it in _______.MATCH THE FOLLOWING: 1. a) Ultrasonics - Frequency below 20Hz b) Speed of sound in air - Needs material medium c) Infrasonic - 330 ms-1 d) Sound propagation - Frequency more than 20000Hz 24
7 MAGNETISMLEARNING OUTCOMES: Differentiates materials, objects, organisms, phenomena and process based on properties, characteristics such as natural and artificial magnets, magnetic field and compares uniform and non-uniform magnetic fields. Classifies materials, objects, organisms, phenomena and process based on properties, characteristics such as natural and artificial magnets. Applies learning to hypothetical situations, such as the concept of Earth’s magnetism. Applies scientific concepts in daily life and solving problems, such as the uses of magnets.MOTIVATION: 1. Have you seen a magnet? 2. How can you find the magnet? 3. What are the uses of magnet?TEACHER ACTIVITY – 1 To know about the pole of the bar magnet, attraction and repulsion between the two magnets. 1. Take a bar magnet and suspend it from a support. 2. Hold another bar magnet in your hand. 3. Bring the north pole of this magnet close to the north pole of the suspended magnet. What do you see? The north pole of the suspended magnet will move away.TEACHER ACTIVITY – 2: 1. Spread some iron fillings collected from the sand uniformly on a sheet of white paper placed on a table. 2. Place a bar magnet below the white sheet. 3. Gently tap the table. What do you see? 25
STUDENT ACTIVITY: To know the difference between magnetic and nonmagnetic materials. Spread some iron pins, stapler pins, iron nails, small pieces of paper, a scale, an eraser and a plastic cloth hanger on a wooden table. Place a magnet nearby these materials. What do you observe? List out the things that are attracted by the magnet? Which objects are not attracted? Tabulate your observations. EVALUATIONI. CHOOSE THE BEST ANSWER:1. A magnet attracts _______. a) Wooden materials b) any metal c) Copper d) Iron and Steel2. One of the following is an example for a permanent magnet _______. a) Electromagnet b) metal c) Soft iron d) Neodymium3. The south pole of a bar magnet and the north pole of a U-Shaped magnet will ____. a) Attract each other b) Repel each other c) Neither attract nor repel each other d) None of the above4. The shape of the Earth’s magnetic field resembles that of an imaginary _____. a) U-Shaped magnet b) Straight conductor carrying warrant c) Solenoid coil d) Bar magnet 26
5. MRI stands for _____. a) Magnetic Resonance Imaging b) Magnetic Running Image c) Magnetic Radio Imaging d) Magnetic Radar Imaging6. A compass is used for _____. a) Plotting magnetic lines b) Detection of magnetic field c) Navigation d) All of theseII. FILL IN THE BLANKS:1. The magnetic strength is ______ at the poles.2. A magnet has _____ magnetic poles.3. Magnets are used in _____ for generating electricity.4. ______ are used to lift heavy iron pieces.5. A freely suspended bar magnet is always pointing along the ____ North-South direction.6. Like poles of magnets repel while unlike poles _____.7. The force of attraction of a magnet is ____ at the poles.8. Now a days, magnets are used to generate ______ in dynamos.9M agnets are used in computers in the storing devices such as hard disks. They are used in _____ and ____ cards also.Match the Following1. a) Magnetite - Magnetic lines b) A tiny pivoted magnet - Natural magnet c) Cobalt - Compass box d) Closed curves - Ferro magnetic material e) Bismuth - Diamagnetic material 27
8 UNIVERSE AND SPACELEARNING OUTCOMES: Classifies materials, objects, organisms, phenomena and processes based on properties or characteristics such as types of rocket fuel. Relates processes and phenomena with causes and effects such as principle behind launching of rockets. Explains processes and phenomena e.g. solar system. Designs models using eco-friendly resources such as parts of rockets.MOTIVATION: Lists out the rockets launched by India between 2010 to 2020 and their functions.TEACHER ACTIVITY – 1: Gives information about the planets to nine students in the class. Ask them to imagine themselves as planets and ask them to tell the characteristics of planets.TEACHER ACTIVITY – 2: Asks the students to take a balloon and blow air into it. Now let the air inside the balloon to come out. What do you observe? You can see the balloon moving in a direction opposite to the direction of the air. Explain the propulsion of rocket.TEACHER ACTIVITY – 3: Shows pictures and videos of rocket fuels and explain its classification and characteristics of different kind of rocket fuels.STUDENT ACTIVITY -1: Prepare a model of the rockets using low cost materials available to you.STUDENT ACTIVITY -2: Prepare a list of Indian satellites launched from Aryabhatta with their purposes.STUDENT ACTIVITY -3 With the help of your teacher gather information about the achievement of India in space research. Prepare an album on the satellite programmers of India. 28
EVALUATIONI. CHOOSE THE BEST ANSWER:1. Which of the following is a celestial body? (a) Sun (b) Moon (c) Stars (d) All the above2. Mangalyaan was sent to _____________. (a) Moon (b) Mars (c) Venus (d) Mercury3. Chandrayan –I was launched on ___________________. (a) 22nd October 2008 (b) 8th November 2008 (c) 22nd July 2019 (d) 22nd October 20194. ________________ is called as Red Planet. (a) Mercury (b) Venus (c) Earth (d) Mars5. Which of the following is the working principle of rockets? (a) Newton’s First Low (b) Newton’s Second Low (c) Newton’s Third Low (d) All the aboveII. FILL IN THE BLANKS:1. The study of stars and planets are known as ___________________.2. Our sun belongs to _________________________ Galaxy.3. _________________ is Inida’s first interplanetary mission.4. _________________ was the first man to walk on the surface of the moon.5. A study of very low temperature is __________________.III. SAY TRUE OR FALSE:1. The sun and the celestial bodies form solar system.2. Chandrayan –I was launched from Sriharikota.3. Mars is the smallest planet in the Solar System.4. PSLV and GSLV are India’s popular satellites.5. The propellant of a rocket is only in the form of solids.IV. MATCH THE FOLLOWING:1. a) Chandrayan - System of millions of stars b) Mangalyaan - Moon c) Cryogenic - Mars d) Galaxy - Satellites kept in the launching rockets e) Payload - Fuel 29
9 MATTER AROUND USLEARNING OUTCOMES: Differentiates materials, and organisms based on the properties or characteristics such as metals, non-metals and metalloids. Classifies meterials and organisms based on the properties or characterisitics such as metals, non-metals and metalloids. Uses scientific conventions, symbols and equations to represent various quantities, elements and units such as symbols of various element.MOTIVATION: - Students are asked to identify the solid, liquid and gaseous items around them. The teacher shows things that exist in three different states.TEACHER ACTIVITY – 1: The teacher explains the methods to determine the symbols of elements. Elements having first letter of their English name as symbol.(eg) Hydrogen – H, Oxygen – O. Elements having first two letters of their English name as symbol. (eg) Helium – He, L ithium – Li Elements having first and Third letters of their English name as symbol. (eg) Chlorine –Cl, Magnesium – Mg Symbols on the basis of their Latin Names (eg) sodium – Latin name-Natrium –Na, Gold - Aurum - Au, Silver - Argentum - Ag. TEACHER ACTIVITY – 2: By simple activities, the teacher explains the differences in the properties of metals and non-metals. Metals are sonorous and used in ringing bells whereas non-metals are non-sonorous and cannot be used in ringing bells. On being hit metals produce a typical sound. This property is being used in making temple bells. (eg). Iron rod - metal charcoal - non metal. 30
TEACHER ACTIVITY – 3: H O Cl Na K Ca Zn C Using the elements enclosed in the cylinder, The teacher writers the molecules formulae of some compounds. Some compounds – HCl, O2, NaCl, CaO….STUDENT ACTIVITYINDIVIDUAL ACTIVITY – 1 Students are asked to write their names and some of their friends names and asked them to find the hidden symbols of elements in their names. List out the names of the elements using the symbols.GROUP ACTIVITY: The students are divided into two groups. The first group is asked to find the metals and the second group is asked to find the non-metals from the group of elements given below. [Iron, Silver, Chlorine, Lead, Carbon, Hydrogen, Mercury, Sulphur] S.No Metals [Group -1] Non-metals [Group -2] 1 2 3 4 EVALUATIONI. CHOOSE THE BEST ANSWER:1. The metal which is in liquid state is ____________________. (a) Carbon (b) Mercury (c) Copper2. Ozone (O3) contains ______________ number of oxygen atoms . (a) 1 (b) 3 (c) 23. The property which allows metals to be hammered into thin sheets is _________. (a) Ductility (b) Malleability (c) Lustras 31
4. The symbol of carbon is _______________. (a) N (b) Na (c) C5. ________________ is a liquid metal which is used in thermometers. (a) Aluminum (b) Mercury (c) PhosphorusII FILL IN THE BLANKS1. Water contains _____________ and __________ element.2. ____________ have high melting point [Metal / Non-metal].3. Every matter exists in _______________, ________________ and ____________ state.4. The symbol of aluminum is _____________________________.5. ___________________ is the chemical name of common salt [Sodium Carbonate / Sodium Chloride].6. The gas which helps to keep swimming pool clean is _________________.7. Ammonia contains ________________ and ___________ element.8. Write the name of any two compounds used in your house.9. Compounds are classified into inorganic compound and ___________ compound.10. The element used to prepare match boxes and rat poison is ____________.III. PICK OUT THE ODD ONE:1. Water, Salt, Sugar, Sulphur2. Aluminum, Gold, Sulpur, IronIV. MATCH THE FOLLOWING:-1. a) Iron - For making wires b) Copper - Sewing needle c) Tungsten - As a fuel for ignition in rocket d) Boron - Making the filament of a bulb.V. WRITE THE CORRECT WORDS FROM THE SCRAMBLED WORDS GIVEN IN THE BRACKET1. The air we breathe consist of ________________ [YGENOX]2. Ornaments are made up of _____________________ [LDGO] 32
10 CHANGES AROUND USLEARNING OUTCOMES: Conducts simple investigations to seek answers to queries. (ex) chemical Changes, factors that determine chemical changes, effects of chemical changes. Explains process and phenomenon involved in chemical changes. Identifies the chemical reactions in day to day life. Relates processes and phenomenon with causes of chemical changes Applies the learning of scientific concepts in day-to-day life and in solving problems. (ex) Effects of chemical changes.MOTIVATION: What will happen when the water is kept in the freezer zone of the refrigerator for sometime? What do you get when the paper is burnt? By asking these types of questions, the teacher tests the previous knowledge of the students and he introduces the concepts of physical changes and chemical changes to the students.TEACHER ACTIVITY – 1:CHEMICAL CHANGES The teacher demonstrates the burning effects of magnesium ribbon. The teacher shows the iron nail to the students and explains the changes taking place on it when it undergoes rusting. Thus the teacher describes the chemical changes and ensures that these changes are irreversible because one or more substances (reactants) undergo a reaction to form one or more new substances (products) Reactants → Products. 33
TEACHER ACTIVITY – 2:FACTORS DETERMINING CHEMICAL CHANGE: The teacher explains the factors determining chemical changes with suitable examples from real life situations a. Contact in physical states – burning matchstick b. Solution of reactants – milk with coffee decoction c. Electricity - Electrolysis d. Heat - Cooking food e. Light - Photosynthesis f. Catalyst – fertilizer for plant growthTEACHER ACTIVITY – 3:EFFECTS OF CHEMICAL CHANGES: The teacher explains about the various effects of chemical changes with examples from real life situations: a. Biological effects – spoilage of food and vegetables b. Environmental effects – pollution, acid rain. Type of Chemical substances Pollution Air Carbon dioxide, Carbon monoxide, Oxides of sulphur, Acid rain, global warming, pollution respiratory problems etc. Water Waste water containing chemical substances Decrease in the quality of pollution Eg. Dyeing industries, Detergents, Oil spillage etc water, skin diseases etc Land Fertilizers like urea, various pesticides, Spoilage of land, cancer, pollution herbicides, solid wastes, plastics etc. respiratory diseases etc.STUDENT ACTIVITY - 1:Classify the following into physical and chemical changes 1. Melting of ice 2. Ripening of fruits 3. Rusting of iron 4. Spoilage of food 5. Burning of wood 6. Bursting crackers 7. Burning of camphor. 34
STUDENT ACTIVITY - 1: Find out the indicators of chemical change for the following process. Burning of crackers Addition of vinegar with baking soda. Addition of water with quicklime. Addition of lemon juice with hot milk. Ripening of fruits Exposure of fresh butter in the air. EVALUATIONI. CHOOSE THE BEST ANSWER:1. Burning of paper is a __________ change. a) physical b) chemical c) physical and chemical d) neutral2. Burning of matchstick is an example for chemical reaction caused by __________ . a) contact in physical states b) electricity c) light d) catalyst3. __________ undergoes rusting. a) Tin b) Sodium c) Copper d) Iron4. Limestone contains __________ mainly. a) calcium chloride b) calcium carbonate c) calcium nitrate d) calcium sulphate5. Which of the following factor induces electrtolysis? a) Heat b) Light c) Electricity d) Catalysis6. In Haber’s process of producing ammonia __________ is used as a catalyst. a) nitrogen b) hydrogen c) iron d) nickel7. Dissolved gases like sulphur dioxide and nitrogen oxides in rain water causes ______ . a) acid rain b) base rain c) heavy rain d) neutral rain8. __________ is/are responsible for global warming. a) Carbon dioxide b) Methane c) Chlorofluorocarbons d) Carbon dioxide, Methane, Chlorofluorocarbons 35
II. FILL IN THE BLANKS.1. Photosynthesis is a chemical reaction that takes place in the presence of __________.2. Iron objects undergo rusting when exposed to __________ and __________.3. __________ is the basic material to manufacture urea.4. Electrolysis of brine solution gives __________ gases5. __________ is a chemical substance which alters the speed of a chemical reaction.6. __________ is the enzyme responsible for browning of vegetables and fruits.III. MATCH THE FOLLOWING:1. a. Rusting Photosynthesis b. Spoilage Decomposition Electrolysi Haber’s process Ozone Biocatalyst Iron Tarnishing Oxygen Food Brine Yeast Chemical reaction Catalysis Decomposition of limestone Calcium oxide FoodIV. ANSWER THE FOLLOWING:1. Explain the role of yeast in making cakes and buns in a bakery?2. Burning of fossil fuels is responsible for global warming. Justify the statement.3. Discuss how acid rain occurs due to emission of smoke from vehicles and industries?4. Is rusting good for iron materials? Explain.5. Do all the fruits and vegetables undergo browning? Explain.6. Identify the following day to day activities based on chemical reactions by physical contact, solutions of reactants, heat, light, electricity and catalyst. a ) Burning of crackers during festivals b) Fading of coloured clothes on drying under sunlight. c) Cooking of eggs. d) Charging of batteries. 36
11 AIRLEARNING OUTCOMES: Relates processes and phenomenon with causes, e.g., smog formation with the presence of pollutants in air; deterioration of monuments with acid rain, etc Draws labelled diagram/ flow charts e.g., Nitrogen cycle. Applies learning of scientific concepts in day-to-day life e.g. preventing air pollution. Makes efforts to protect environment, e.g., using resources judiciously; making controlled use of fertilisers and pesticides; suggesting ways to cope with environmental hazards, etcMOTIVATION: 1. Air is a mixture of gases. Justify. 2. Why trees are considered to be important to life? 3. What may be the reason for ozone layer depletion? 4. If oxygen has the capacity to burn itself, striking a matchstick will be enough to burn all the oxygen in our planet’s atmosphere. 5. Oxygen is about two times more soluble in water than nitrogen. If it had the same solubility as nitrogen, then less oxygen would be present in seas, lakes and rivers that will make life much more difficult for living organisms. 6. Soda bottle bursts at times when it is opened during summer. Why? 7. It is said that sleeping beneath the tree during night is not good for health. What is the reason? 8. Why does the fish die when it is taken out of water? 9. How do astronauts breathe when they go beyond earth’s atmosphere? 10. Now-a-days nitrogen is used as a substitute for compressed air in tyres. Have you noticed it? Why do people prefer nitrogen instead of compressed air in tyres? 37
TEACHER ACTIVITY – 1: Teacher gives the introduction on composition of air. Air is a mixture of gases that surrounds our planet earth. It is essential for the survival of all the living things. Air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide and small amount of other gases. We breathe in oxygen and breathe out carbon dioxide. Plants in turn use carbon di oxide for photosynthesis and release oxygen into the atmosphere.TEACHER ACTIVITY – 2: The teacher explains the following with suitable examples and chemical equations. Physical and chemical properties of gases,like oxygen, carbondioxide and nitrogen. their reaction with metals and nonmetals uses of oxygen, nitrogen and carbon di oxide Nitrogen cycleTEACHER ACTIVITY – 3: Environmental protection against pollution: Teacher explains the concepts like green house effect, global warming and acid rain with the help of given pictures. 38
STUDENT ACTIVITY – 1 Heat a strip of magnesium ribbon in the flame till it catches fire and introduce it into the jar containing oxygen. It burns with a dazzling bright light and white ash of magnesium oxide is formed. Heat a small piece of phosphorous and introduce it into the oxygen jar. Phosphorous burns with suffocating smell and gives phosphorous pentoxide (white fumes).STUDENT ACTIVITY – 2 Pluck any legumionous plant and observe the root nodules. Why do nitorgen is very important for plant growth? Find reason.STUDENT ACTIVITY - 3 Open the Browser and type the URL given below. Click on any one of the items to know about carbon emission, climate change, global average temperature, sea level etc. For example, click on the “Climate Time Machine” a popup screen will open. In that you can able to see carbon emission, global average sea level, temperature, sea ice, etc. When you click global average sea level, you will find year wise sea level. Browse in the link: https://climatekids.nasa.gov/menu/play 39
EVALUATIONI. CHOOSE THE BEST ANSWER:1. Which of the following is true about oxygen? . a) Completely burning gas b) partially burning gas c) doesn’t support burning d) support burning2. Aerated water contains . a) air b) oxygen c) carbon dioxide d) nitrogen3. Solvay process is a method to manufacture . a) lime water b) aerated water c) distilled water d) sodium carbonate4. Carbon dioxide with water changes . a) blue litmus to red b) red litmus to blue c) blue litmus to yellow d) doesn’t react with litmus5. Which of the following is known as azote? a) Oxygen b) Nitrogen c) Sulpher d) Carbon dioxideII. FILL IN THE BLANKS:1. ___________ is called as vital life.2. Nitrogen is ___________ than air.3. ___________ is used as a fertilizer.4. Dry ice is used as a ___________.5. The process of conversion of iron into hydrated form of oxides is called ___________.III. ANSWER THE FOLLOWING:1. Mention the physical properties of oxygen.2. List out the uses of nitrogen.3. Write about the reaction of nitrogen with nonmetals.4. What is global warming?5. What is dry ice? What are its uses? 40
12 ATOMIC STRUCTURELEARNING OUTCOMES Calculates using the data given, such as atomic number, atomic mass, fundamental particles of an atom and valency of elements. Measures physical measurements using appropriate devices and equipments. (ex) law of conservation of mass, law of constant proportions. Explain process and phenomenon such as Thomson’s atomic ModelMOTIVATION: - 1. Our body is made up of cells 2. All matters are made up of small particles called atoms. To illustrate this, a piece of chalk is taken and broken into pieces repeatedly.TEACHER ACTIVITY -1: From the fundamental particles (Proton, Electron and Neutron), calculate the atomic number and atomic mass. Teacher explains with an example. Consider an element, it is denoted as X = Element = Atomic Mass (or) Mass Number – [p+n] = Atomic Number- [p or e] (eg): 41
— Find Z,A and number of neutrons A–Z=n 23 – 11 = 12 A = 23, Z = 11, n = 12TEACHER ACTIVITY -2:Illustrate the law of conservation of mass Total mass of the reactant = Total mass of the products (eg) Take a piece of ice in a clear tightly closed conical flask and weigh it. Leave the flask for sometime. Now observe the flask. The ice melts and becomes water. Weigh the flask again. We find the total mass of the matter remains the same. It is implied that mass can neither be created nor be destroyed during a physical change.STUDENT ACTIVITY -1: Students are asked to calculate and tabulate the number of proton, electron, neutron, atomic number and mass number given below S.no Element No of protons No of No of Atomic Atomic Mass electrons neutrons Number (z) (A) 1 2 3 4STUDENT ACTIVITY -2: The teacher cuts awatermelon into two halves and explains that the seeds embedded in the watermelon resembles electrons and the red edible portion represents the positive sphere called protons. Then the students are asked to construct Thomson’s atomic model using card board and black beeds. 42
STUDENT ACTIVITY -3: The teacher explains that the valency of an element is calculated on the basis of the valency of hydrogen, oxygen and chlorine and then the students one asked to find the valency of elementsrepresented in the square boxes for the following compounds.. Find the valency for the elements represented in the square box. O Mg N H H Cl Cl H H H EVALUATIONI. CHOOSE THE BEST ANSWER:1. Cathode rays are made up of __________________. a. Positively charged particles b. Neutral particles c. Negatively charged particles.2. Who discovered electron? a. Rutherford b. John Dalton c. J.J.Thomson3. James Chadwick discovered _________________. a. Newton b. Proton c. Electron4. Mass of proton is _____________. a. 1.6×10-24 grams b. 9.1×10-28 grams c. 1.6×10+24 grams5. The negatively charged rays are called as _______________. a. Anode rays b. Cathode rays c. Eletric rays 43
II FILL IN THE BLANKS1. ________________ is the smallest particle of an element.2. In water, hydrogen and oxygen are combined in the ratio of _____________ by mass.3. Proton is deflected towards the ________________ charged plate. (Positively / Negatively)4. The law of conservation of mass was stated by ___________.5. Cathode rays travel in _______________.6. Same element having different mass number is called _____________ . [Isotope / Isobar]7. According to Dalton’s atomic theory, atoms can neither be _______________ nor be ______________.8. Electrons revolving around the nucleus in a circular path is called _________________.9. The total number of proton and neutron in an atom is called __________. [atomic number / atomic mass]10. Nucleus consists of ____________ and ______________ .III. FIND THE VALENCY:1. The valency of C in CO2 is _________________ .2. The valency of Na in NaCl _________________ .IV. MATCH THE FOLLOWING:1. a) Law of Conservation of Mass — Sir Willium Crookes b) Law of Constant Proportion — James Chadwick c) Cathode Rays — Joseph Proust d) Anode Rays— Lavoisier e Neutrons— GoldsteinV. FIND THE NUMBER OF NEUTRONS IN AN ELEMENT:1. 6C12 = Number of neutron _______________2. Ar40 18 = Number of neutron _______________ 44
13 WATERLEARNING OUTCOMES: Conducts simple investigations to seek answers to queries e.g., to test water pollution Relates processes and phenomenon with causes, e.g.,causes of water pollution Explains processes and phenomenon, e.g., water treatment methods, softening of water. Applies learning of scientific concepts in day-to-day life, e.g., purifying water.MOTIVATION: 1. Teacher asks students to take/draw the picture of a polluted water body found near their residence and identify the source of pollution. 2. What is the source of drinking water available to you at home? 3. How do you get purified water at your school? 4. Write an essay on causes, effects of water pollution and ways to prevent it.TEACHER ACTIVITY -1: Teacher introduces the lessons with the help of the given concept map. Three fourths of our planet earth is filled with water. Water exists in three states namely solid, liquid and gas. Water on the surface of the earth is found mainly in oceans (97.25%), polar ice caps and glaciers (2.05%) and the remaining is in lakes, rivers and aquifers - ground water. Even our body is made up of water (65%). 45
TEACHER ACTIVITY -2: Teacher explains laboratory preparation of water with the help of the given picture. Physical properties and chemical properties are to be explained by the teacher with chemical equations at suitable places.TEACHER ACTIVITY -3: Process of water purification is to be explained by the teacher with the help of the given picture.TEACHER ACTIVITY – 4: With the help of the given chart, pollution of water is to be explained by the teacher. Students can be given a task to identify the sources of water pollution and ways to prevent it. 46
STUDENT ACTIVITY -1: Take samples of water from different sources (like a tube well, a lake, a pond or a river) and pour equal quantities of each sample of water into different test tubes. Measure the height of water in each test tube with a scale. Add one or two drops of liquid soap to each test tube. Shake each test tube five times and observe the height of the lather in each sample. Record your observations in the table. Which water is soft? Which water is hard? Can you say why?STUDENT ACTIVITY -2: Identify the method of water treatment followed at your residence. Find out the place where the sewage and domestic waste at your residence is released? From the given table of water pollutants which is the source of pollution at your location? EVALUATIONI. CHOOSE THE CORRECT ANSWER.1. Water changes to ice at . a) 0oC b) 100oC c) 102oC d) 98oC2. Solubility of carbon dioxide in water is high when the . a) pressure is low b) pressure is high c) temperature is high d) None of the above3. The gas collected at the cathode on electrolysis of water is . a) oxygen b) hydrogen c) nitrogen d) carbon dioxide4. Which of the following is a water pollutant? a) Lead b) Alum c) Oxygen d) Chlorine 47
