202110206-APEX-STUDENT-WORKBOOK-PHYSICAL_SCIENCE-G08-PART2

Physical Science Workbook_8_P_2.pdf 1 17-10-2019 19:43:28 Name: ___________________________________ Section: ________________ Roll No.: _________ School: __________________________________

Table of Contents 1 26 7 COAL AND PETROLEUM 50 8 COMBUSTION, FUELS AND FLAME 67 9 ELECTRICAL CONDUCTIVITY OF LIQUIDS 91 10 REFLECTION OF LIGHT AT PLANE SURFACES 110 11 SOME NATURAL PHENOMENA 137 12 STARS AND THE SOLAR SYSTEM 138 PROJECT BASED QUESTIONS ADDITIONAL AS-BASED PRACTICE QUESTIONS TABLE OF CONTENTS

7. COAL AND PETROLEUM SESSION 1 INTRODUCTION AND SOURCES OF MATERIALS 1.1 Mind Map 1. Sources of materials SESSION 1. INTRODUCTION AND SOURCES OF MATERIALS 1

2. Fossil fuels 1.2 Terminology i. Material Science –The branch of science which deals with materials is called material science. SESSION 1. INTRODUCTION AND SOURCES OF MATERIALS 2

ii. Wind Mills – A windmill is a mill that converts the energy of wind into rotational energy by means of vanes called sails or blades. iii. Bio–diesel – Fuel that is made from natural elements such as plants,vegetables, and reusable materials. Bio-diesel can be produced from straight vegetable oil, animal oil/fats and waste cooking oils. iv. Fossil Fuel – Fosssil fuels are sources of energy that have developed within the earth over millions of years.They are nonrenewable. e.g–Petroleum, Coal, etc. 1.3 Key Concepts i. We use various materials to meet our basic needs, some of them are found in nature. ii. Natural resources can be classified into exhaustible and inexhaustible resources. iii. Natural resources: Air, water and wind are the natural resources. iv. Exhaustible resources: The resources which get exhausted and cannot be renewed. v. Inexhaustible resources: The resources which cannot be exhausted – renewable re sources. vi. Fossil fuels are formed from the dead remains of organisms under the earth over millions of years. vii. Fossil fuels are exhaustible. 1.4 Conceptual Understanding Q1. Complete the given analogy: [Refer to TB page 107 Q1] A. i. Coal: exhaustible : : wind: inexhaustible ii. Coal tar: synthetic dyes : : coke: manufacture of steel iii. Petrochemical: plastic : : CNG: fertilisers iv. Carbon–dioxide: global warming : : paints: nausea SESSION 1. INTRODUCTION AND SOURCES OF MATERIALS 3

1.5 Communication Through Drawing and Model Making Q1. Draw a flow chart showing exhaustible and inexhaustible resources and their use. [Re- fer to TB page 109 Q10] A. 1.6 Application to Daily Life, Concern to Bio Diversity Q1. Why should people look for alternatives to fossil fuel? [Refer to TB page 109 Q14] A. Fossil fuels cause air pollution, greenhouse effect and global warming. They are also exhaustible. Therefore, they need to be replaced in use by other inexhaustible and healthier alternatives. The fossil fuels on earth are ending, we need alternative sources of energy to cope with the increasing demand for energy, i.e, fuels. Without alternative sources of energy the world would be deprived of basic needs such as electricity, potable water, and manufactured foods. SESSION 1. INTRODUCTION AND SOURCES OF MATERIALS 4

SESSION 2 COAL, PETROLEUM AND NATURAL GAS 2.1 Mind Map 1. Coal 2. Petroleum – 5 SESSION 2. COAL, PETROLEUM AND NATURAL GAS

2. Petroleum SESSION 2. COAL, PETROLEUM AND NATURAL GAS 6

3. Natural Gas SESSION 2. COAL, PETROLEUM AND NATURAL GAS 7

2.2 Terminology i. Coke – A solid fuel made by heating coal in the absence of air so that the volatile components are driven off. ii. Coal gas – A gaseous mixture produced by the destructive distillation of bituminous coal and used as a commercial fuel. iii. Coal tar – A viscous black liquid containing numerous organic compounds that is obtained by the destructive distillation of coal and used as a roofing, waterproofing, and insulating compound and as a raw material for many dyes, drugs, and paints. iv. Carbonisation – Carbonisation is the term for the conversion of an organic substance into carbon or a carbon–containing residue through pyrolysis or destructive distilla- tion. v. Planktons – The small or microscopic organisms that drift or swim weakly in a body of water, including bacteria, diatoms, jellyfish, and various larvae. 2.3 Key Concepts i. Petroleum is formed from the remains of tiny organisms called planktons. ii. Fractional distillation is the separation of a complex mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heat- ing them to the specific temperature at which one or more fractions of the compound will vaporize. iii. Natural gas is a naturally occurring hydrocarbon mixture consisting primarily of methane, with other hydrocarbons, carbon dioxide, nitrogen, hydrogen sulphide, etc. iv. Petroleum gas, petrol, diesel, kerosene, paraffin wax, lubricating oil are obtained by refining petroleum. v. The useful substances obtained from petroleum and natural gas are called petro- chemicals. vi. The slow process of conversion of dead vegetation into coal is called carbonisation. vii. Coke, coal tar, coal, and gas are the products of coal. SESSION 2. COAL, PETROLEUM AND NATURAL GAS 8

2.4 Conceptual Understanding Q1. Match the following: [Refer to TB page 107 Q2] i. natural resource [ ] a. carbonization ii. coal [ ] b. plastic chair iii. petrochemical product [ ] c. krishna and godavari delta iv. natural gas [ ] d. Plankton v. petroleum [ ] e. water A. (i) – (e), (ii) – (a), (iii) –(b), (iv) – (c) and (v) – (d) Q2. Multiple choice questions [Refer to TB page 107 Q3] A. i. Which one of the following is a less polluting fuel? (a. Natural gas) a. Natural gas b. Coal c. Kerosene d. Petrol ii. The main constituent of coal is (a. Carbon) a. Carbon b. Oxygen c. Air d. Water SESSION 2. COAL, PETROLEUM AND NATURAL GAS 9

3. Which one of the following is used in making of shoe polish? (a. Paraffin wax) a. Paraffin wax b. Petrol c. Diesel d. Lubricating oil Q3. Name the petroleum products used for roads surfacing. [Refer to TB page 94 Q5] A. Asphalt and bitumen. Q4. Explain the process of formation of petrol. [Refer to TB page 94 Q6] A. Petroleum was formed from the remains of tiny organisms called plankton that were found in the bottom of seas and oceans. Planktons have tiny droplets of oil inside their bodies. As these organisms died, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. Over millions of years in absence of air, high tem- perature and high pressure transformed the dead organism into petroleum and natural gas. Q5. Fill in the blanks. [Refer to TB page 108 Q4] i. Coke was used in the manufacture of steel. ii. The biproduct of coal used in synthetic dyes and paints is coal tar. iii. Coal was formed in areas where large amounts of plants was buried under the Earth. iv. Carbon dioxide gas whuch cause climate change and global warming. SESSION 2. COAL, PETROLEUM AND NATURAL GAS 10

2.5 Information Skills and Projects Q1. Project Work Compare a CNG run vehicle with that of a diesel run vehicle. What differences do you notice in both cases with respect to pollutants released, level of pollution and cost of fuel? Prepare a report on your findings. You can take the help of a driver to make a report on your observations. [Refer to TB page 108 Q7] A. Name of the fuel Cost of the fuel as Pollutants on today liberated Diesel/petrol 60.00/83.00 Diesel has significantly lower CO2 emissions than petrol but has higher NOx and particulate emissions, carbon monoxide, carbon dioxide, hydrocarbons, sulphur dioxide. CNG 52 CNG has much lower CO2 and particulate emissions, carbon dioxide, sulphur dioxide. Note: Petrol, diesel and CNG rates vary with time and place. SESSION 2. COAL, PETROLEUM AND NATURAL GAS 11

Q2. Project Work Choose five families in your neighbourhood, collect the information about the measures that they adopt to conserve energy resources in transport and cooking. [Refer to TB page 108 Q8] Name of Number of Number of Amount Amount the head of members vehicles spent for spent for the family using fuel per cooking in the purpose family month A. Students’ activity. Q3. The following table shows the total power shortage percentage in India from 1991–1997. Show the data in the form of a bar graph taking shortage percentage from the years on the Y–axis and the years on the X–axis. [Refer to TB page 109 Q9] SESSION 2. COAL, PETROLEUM AND NATURAL GAS 12

S. No. Year Shortage (%) 1 1991 7.9 2 1992 7.8 3 1993 8.3 4 1994 7.4 5 1995 7.1 6 1996 9.2 7 1997 11.5 (a) Is the shortage percentage of power increasing or decreasing? (b) If shortage percentage of power increases year by year, how will it affect human life? Explain. A. (a) Except in the years 1992, 94, 95 –all remaining years’ power shortage has increased. (b) There are so many problems due to power shortage: SESSION 2. COAL, PETROLEUM AND NATURAL GAS 13

i. Industries will not be able to run their work properly. Industries mainly run with electric power. If electric power is not sufficient then it is major set back for their production. ii. Crop yield will decrease. Agriculture mainly depends on electric power for water supply. If there is no sufficient power is available then the yield of food material decreases. iii. Industrial sector growth will decrease which will affect the country’s economy. iv. Shortage of power also affects the health of people because many get cured by operations which require power. 2.6 Communication Through Drawing and Model Making Q1. Collect information about places where you get coal, petroleum and natural gas in Andhra Pradesh and mark the places on an outline map of Andhra Pradesh. [Refer to TB page 109 Q11] A. Students' activity. Godavari Valley Coal field is located in the districts of Adilabad, Karimnagar, Khammam and Warangal in the Indian state of Telangana . It is the only coal field in South India. It lies in the basin of the Godavari River. The petroleum and natural gas reserves are there in Kaikaluru, Rajolu, Narsapuram, Amalapuram, Pasarlapadu etc. also extending in Krishna, East Godavari, West Go- davari districts. 2.7 Appreciation and Aesthetic Sense, Values Q1. How would you appreciate the efforts of human beings to discover an alternate energy source like coal and petroleum for their daily use? [Refer to TB page 109 Q12] A. It is highly appreciable that humans discovered alternate energy source like coal and petroleum for the human needs. It helped a lot for the development. SESSION 2. COAL, PETROLEUM AND NATURAL GAS 14

Coal and petroleum are exhaustible resources. These are the resources that are widely used in our daily life. Earlier people used kiln using wood for cooking food and for travelling they used horses and bullock carts. There was no electricity, so their life was miserable. The wood they were using produced lot of pollution. So they required a fuel not only for cooking purpose but also for travelling long distances. In 19th century, the useof coal as fuel was the major thing in development of human beings. Steam engine which used coal was invented during industrial revolution. Petroleum was started as fuel in in 1859 then it was used everywhere in the world because it was better fuel than coal and less pollutant. To meet future energy needs scientists are working for alternate energy sources. Bio–fuel is one of the alternate resources which is renewable. Scientists have also developed methods to harness solar energy, wind energy, tidal energy, etc. 2.8 Application to Daily Life, Concern to Bio Diversity Q1. Assume that you are a driver, what measures do you take to save petrol and diesel? [Refer to TB page 109 Q15] A. · Turning off vehicle regularly. · Driving at economical speed. · Stopping engine at signals and during waiting period. · Ensuring correct pressure in tyres. · Ensuring regular maintenance of vehicle. Q2. \"The use of CNG and LPG as fuels for automobile helps us to minimize air pollution and maintaining eco-logical balance\". Do you agree with this statement? If yes, explain. [Refer to TB page 109 Q17] A. Yes, I agree with the statement because they reduce pollution. They neither emit smoke nor harmful gases. So their use has no adverse effect on ecological imbalance as the organisms living in that area do not get disturbed. Q3. “Crude oil and refined fuel when spill into the sea from tanker or ships by accident.” Discuss the consequences of this on the environment. [Refer to TB page 109 Q16] SESSION 2. COAL, PETROLEUM AND NATURAL GAS 15

A. Crude oil and refined fuel spills from tanker or ships by accident cause damage to natural ecosystem. This can kill sea birds, mammals, shell–fish and other organisms. CONSEQUENCES: Thousands of birds, fishes, sea animals and seals die due to spilling of oil which pollute the natural ecosystem of sea or ocean. About 2 million tonnes of oil spills into the sea every year from oil tankers, mostly during collisions or other accidents. When oil is discharged into the sea and washed up on shorelines they harm many birds and creatures. —— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. State true or false. [Refer to Session 7.2 ] (i) We can reduce the consumption of both coal and petroleum by opting for a different model of development, which does not depend on these resources or re- duce the wastage of these resources. [] (ii) Petroleum is separated into its various components by a separation technique known as distillation. [] 2. Match the following. [(Session 7.2)] Column A [] Column B i. Naphthalene a. Polishes ii. Kerosen [] b. Chemicals iii. Lubricating oil [] c. Roads iv. Bitumen [] d. Central heating v. Fuel oil [] e. Jet fuel 3. Answer the following questions in one sentence. [Refer to Session 7.2 ] CHAPTER 7. COAL AND PETROLEUM 16

(i) Name some alternatives to natural gas. (ii) Can you imagine spending a day without using petrochemical products? List how often you use products obtained from petrochemicals. Can you imagine life 100 years ago when these were not available? (iii) State any one instance where energy or fuel resources are misused in our daily life. (iv) Suggest one alternate way to save exhaustible fuel resources. (v) How is biodiversity affected by excessive use of fossil fuels? (vi) What are the consequences faced by misuse of fuels? 4. Fill in the blanks. [Refer to Session 7.2 ] (i) Food was cooked using as fuel in the olden days, now is being used. (ii) Petroleum is also called due to its great commercial importance. (iii) The steam engine which used was invented during the industrial revolution. (iv) Nowadays, is mostly used to produce electricity in thermal power plants. (v) One barrel petroleum equals litres. (vi) More than 4000 years ago, was used in the construction of walls and towers of Babylon. 5. State true or false. [Refer to Session 7.1 ] (i) Carbon dioxide is a major cause for global warming. [] CHAPTER 7. COAL AND PETROLEUM 17

6. Answer the following questions in one sentence. [Refer to Session 7.1 ] (i) How are resources classified based on whether they are expected to last forever or not? (ii) Wind is an important natural resource. How was wind power harnessed in olden days? 7. Fill in the blanks. [Refer to Session 7.1 ] (i) Wind is an resource. Short Answer Type Questions 8. Answer the following questions in 3-4 sentences. (i) [(Session 7.2)] What are petrochemicals? Where are they used? 9. Answer the following questions in 3-4 sentences. (i) [(Session 7.1)] What are exhaustible and inexhaustible resources? (ii) [(Session 7.1)] Why should people look for alternative sources to fossil fuels? (iii) [(Session 7.1)] What are the uses of wood? Is it an exhaustible or inexhaustible re- source? (iv) [(Session 7.1)] Write the articles/materials that we use today instead of the following. Clay jars, Banana leaves, Metal trunks Long Answer Type Questions 10. Answer the following questions in 6-8 sentences. (i) [(Session 7.2)] Write short notes on coal tar. (ii) [(Session 7.2)] Describe the process of formation of petroleum. CHAPTER 7. COAL AND PETROLEUM 18

(iii) [(Session 7.2)] How is coal formed? 11. Answer the following questions in 6-8 sentences. (i) [(Session 7.1)] Why are coal and petroleum so versatile? AS2-Asking questions and making hypothesis Short Answer Type Questions 12. Answer the following questions in 3-4 sentences. (i) [(Session 7.2)] Suhas’s father told to use cycle instead of bike so that we can save petrol. Is he correct? Why? (ii) [(Session 7.2)] Your friend says ‘Coal is an ancient gift serving modern society’. Is it true? Why do you think so? Long Answer Type Questions 13. Answer the following questions in 6-8 sentences. (i) [(Session 7.2)] Neha learnt a lesson about petrochemicals in class and thought about it while returning home. She had many questions in her mind. What questions might these be? AS3-Experimentation and field investigation Long Answer Type Questions 14. Answer the following questions in 6-8 sentences. (i) [(Session 7.2)] Suggest an experiment to show that a gas which can burn is evolved when we heat high quality coal. CHAPTER 7. COAL AND PETROLEUM 19

AS4-Information skills and projects Very Short Answer Type Questions 15. Answer the following questions in one sentence. [Refer to Session 7.2 ] (i) Complete the table by writing ‘source from which the material is obtained’. Material Source Glass Plastics Short Answer Type Questions 16. Answer the following questions in 3-4 sentences. (i) [(Session 7.2)] Choose five families of your neighbourhood, collect the information about the measures that they adopt to conserve energy resources in transport and cooking. Make a report on your observation. (ii) [(Session 7.2)] Go to a petrol pump and collect information on the amount of petrol and diesel they sell in a day. Based on that, try to estimate how much petrol and diesel is used in your town in one day. 17. Answer the following questions in 3-4 sentences. (i) [(Session 7.1)] Complete the table by writing ‘source from which the material is ob- tained’. Material Source Metals Wood Clay CHAPTER 7. COAL AND PETROLEUM 20

Long Answer Type Questions 18. Answer the following questions in 6-8 sentences. (i) [(Session 7.2)] Collect information on the presence of alternate sources of energy in India. Make a short report on where solar, hydro and wind energy is used and how much of the power demand is met by these three renewable sources. (ii) [(Session 7.2)] Mention the uses of petrochemicals in various sector in a table. AS5-Communication through drawing and model making Short Answer Type Questions 19. Answer the following question. (i) [(Session 7.2)] Draw an experimental setup to show that when we heat high quality coal a gas evolves which can burn. Long Answer Type Questions 20. Answer the following questions in 6-8 sentences. (i) [(Session 7.2)] (a) Draw a neatly labeled diagram showing the various uses of coal tar. (b) Draw a diagram showing some useful products of coal. AS6-Appreciation and aesthetic sense, Values Short Answer Type Questions 21. Answer the following questions in 3-4 sentences. (i) [(Session 7.2)] Give some instances where we misuse energy resources. What are its consequences? (ii) [(Session 7.2)] Why is Bio –diesel used as an alternative fuel source? Long Answer Type Questions 22. Answer the following questions in 6-8 sentences. (i) [(Session 7.2)] Why do you appreciate coal which is an ancient gift serving modern society? CHAPTER 7. COAL AND PETROLEUM 21

AS7-Application to daily life, concern to bio diversity Short Answer Type Questions 23. Answer the following questions in 3-4 sentences. (i) [(Session 7.2)] How does carelessness in handling petroleum products lead to harmful effects on the environment? (ii) [(Session 7.2)] Give two examples each from agricultural, industrial and the domestic sectors to show that petrochemicals are now used in all walks of life. (iii) [(Session 7.2)] Why has the price of petrol increased dramatically in the last 20 years? (iv) [(Session 7.2)] What are the environmental and health concerns regarding the use of fossil fuels? Objective Questions AS1-Conceptual Understanding 24. Choose the correct answer. (i) Petrochemicals are used in the manufacture of the following. (A) Metals (B) Coal tar (C) Plastic (D) Glass (ii) Petroleum and coal are . (A) gases (B) metals (C) energy (D)fossil fuels (iii) CNG stands for . (A) Compressed Natural Gas (B) Compact National Gas (C)Compound Natural Gas (D)Coated Natural Gas CHAPTER 7. COAL AND PETROLEUM 22

(iv) is/ are not a petroleum product. (A) Metals (B) Petroleum (C) Coal (D) Diesel (v) is used for surfacing of roads. (B) Asphalt (A) Coke (C)Paraffin wax (D) Lubricants (vi) is stored under high pressure. (B) CNG (A) Coal (C) Kerosene (D) Wood (vii) gas is obtained during the processing of coal to get coke. (A) Coal (B) LPG (C) CNG (D)None of the above. (viii) The ‘almost pure form of carbon’ is used in . (A) pesticides (B) synthetic dyes (C) lighting (D)extraction of metals (ix) The slow process of conversion of dead vegetation in to coal is called . (A) oxidation (B) hybridization (C) carbonization (D) hydroxylation AS3-Experimentation and field investigation 25. Choose the correct answer. (i) is obtained by mixing the mineral kaolinite with water. (A) Plastics (B) Glass (C) Clay (D) Wood CHAPTER 7. COAL AND PETROLEUM 23

(ii) Petroleum is separated into various components by ___________ . (A) sedimentation (B) filtration (D)fractional distillation (C) centrifugation (B) petrol AS4-Information skills and projects (D)paraffin wax (B) liquid treasure 26. Choose the correct answer. (D)liquid platinum (i) Vaseline is made from . (A) diesel (C) kerosene (ii) Petroleum is also known as . (A) black gold (C)black magic AS6-Appreciation and aesthetic sense, Values 27. Choose the correct answer. (i) The unlimited resources in nature that can be used over and over again are called . (A) fuels (B) renewable resources (C) energy (D) gases (ii) Petroleum is formed from the remains of tiny product called . (A) algae (B) plankton (C) azolla (D) azotobacter CHAPTER 7. COAL AND PETROLEUM 24

AS7-Application to daily life, concern to bio diversity 28. Choose the correct answer. (i) Which of the followings will be consequence/consequences of excessive use of petroleum and its products? (A) Increased prices of food (B) Depletion of resources (C)Rising of oil price (D)Both B and C CHAPTER 7. COAL AND PETROLEUM 25

8. COMBUSTION, FUELS AND FLAME SESSION 1 COMBUSTION, TYPES OF COMBUSTION AND IGNITION TEMPERATURE 1.1 Mind Map 1. Combustion SESSION 1. COMBUSTION, TYPES OF COMBUSTION AND IGNITION TE... 26

2. Types of Combustion 1.2 Terminology i. Magnesium ribbon – A light, silvery–white, moderately hard metallic element that in ribbon or powder form burns with a brilliant white flame. ii. Fire extinguisher – A portable device that discharges a jet of water, foam, gas, or other material to extinguish a fire. iii. CNG – It stands for Compressed Natural Gas. Compressed natural gas, or CNG, is natural gas storred under pressure which remains clear, odourless, and non–corrosive. 1.3 Key Concepts i. We use different types of materials around us as fuels in our daily life. ii. Combustion: A chemical process in which a material reacts with oxygen present in the air to generate heat is called combustion. iii. Combustion is of different types –rapid, slow, spontaneous, and explosion. iv. Ignition temperature, a combustible substance, and a supporter of combustion are necessary for combustion. v. Ignition temperature: The temperature at which a substance catches fire is called ignition temperature. vi. Inflammable material: The substances which have very low ignition temperature and catch fire easily are known as inflammable substances. vii. Spontaneous combustion: The type of combustion in which material burns into flames without the application of any apparent cause is called spontaneous combustion. SESSION 1. COMBUSTION, TYPES OF COMBUSTION AND IGNITION TE... 27

viii. Rapid combustion: The combustion which takes place on heating and burns vigor- ously till the availability of fuel. ix. Slow combustion is a form of combustion which takes place at low temperatures. x. Materials are of two types combustible and non–combustible. Oxygen is necessary for combustion. xi. Combustible materials: Liable to catch fire and burn easily. xii. Non–combustible materials: Materials which can’t catch fire and burn. 1.4 Conceptual Understanding Q1. Give four examples of combustible materials. [Refer to TB page 120 Q1] A. Petrol, kerosene, coal, wood. Q2. Give four examples of non–combustible materials. [Refer to TB page 120 Q2] A. Glass, pebble, iron, stone. 1.5 Asking Questions and Making Hypothesis Q1. What would happen if oxygen stops to support combustion? Make a guess. And if that is the situation, for what other works fuels are useful? [Refer to TB page 120 Q10] A. If oxygen stops supporting combustion, the burning process also stops. Then fossil fuels will not be of any use for production of heat, energy and electricity. So, we have to prefer alternative source of energy like solar energy, wind energy, tidal energy etc. SESSION 1. COMBUSTION, TYPES OF COMBUSTION AND IGNITION TE... 28

1.6 Experimentation and Field Investigation Q1. Project work : Collect information about the experiments of Joseph Priestly. Write a two page report describing Priestly’s experiments proving that oxygen is needed for burning. [Refer to TB page 121 Q4, Try These] A. Collect information from the internet to make the project report. [Reference Answer] – Joseph Priestly performed the following experiment to prove that oxygen is needed for burning. Priestley, first lit a candle and placed a glass jar over it and watched as the flame gradually died out. Priestley reasoned that something in the air was necessary to keep the flame burning. Priestley then placed fresh mint leaves underneath the jar and allowed the entire setup to sit for a few days. After few days, Priestley found that he could relight the candle and it would burn for a while. Priestley concluded that the plant had produced the substance required for burning. For knowing the substance which is in air, produced by plant and which is used for burning, he did another experiment in which Priestley put a mouse under the jar and waited to see what would happen. Sadly, the mouse eventually died. Later, Priestley put a mouse under the jar with fresh mint leaves and waited to see what would happen. To his surprise, both the mouse and plant survived for quite some time. Then he concluded that the substance which is used for burning the candle is same which is used for the survival of mouse. By this way Joseph Priestly proved that the important substance produced by the plant is used for burning the candle and surviving of mouse is oxygen.] SESSION 1. COMBUSTION, TYPES OF COMBUSTION AND IGNITION TE... 29

A few sites that you can use are: i. https://www.youtube.com/watch?v=T1vGBFIw7I0 ii. http://www.juliantrubin.com/bigten/oxygenexperiments.html 1.7 Application to Daily Life, Concern to Bio Diversity Q1. Where do you find spontaneous combustion and rapid combustion in your daily life? [Refer to TB page 121 Q18] A. Burning of gas stove is an example of rapid combustion. Burning of phosphorous at the head of a match stick is an example of spontaneous combustion. SESSION 1. COMBUSTION, TYPES OF COMBUSTION AND IGNITION TE... 30

SESSION 2 FUELS, FLAME AND STRUCTURE OF A FLAME 2.1 Mind Map 1. Factors to be considered to choose fuel 2. Types of fuel SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 31

3. Fire 4. Fire Control – 4. Fire Control SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 32

SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 33

2.2 Terminology i. Non Luminous Zone – The non–luminous zone is the zone of complete combustion. It looks like an “aura” formed around the candle and is almost invisible. It is the hottest zone as “around” the candle flame, the ample presence of oxygen aids in complete combustion. This zone is blue in colour. ii. Luminous Zone – The luminous zone is the zone which is moderately hot with limited oxygen supply as the molten wax further vaporizes and burns in the presence of oxygen and soot particles. The colour of this zone is yellowish. iii. Wax – Any of various natural, oily or greasy heat sensitive substances, consisting of hydrocarbons or esters of fatty acids that are insoluble in water but soluble in nonpolar organic solvents. 2.3 Key Concepts i. Fuels are the materials which liberate heat and light on burning. ii. Fuels can be solid, liquid or gaseous in nature. SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 34

iii. Control of fire can be done by cutting the supply of one of the required materials: fuel, air or heat. iv. Flame is a zone of oxidation. v. Explosion: The process by which huge amounts of sound and heat are released at a time. vi. Calorific Value: The amount of energy liberated by complete combustion of 1 kg of a fuel. 2.4 Conceptual Understanding Q1. Why should not we store spirit or petrol near our living place? [Refer to TB page 120 Q3] A. Petrol and spirit are highly volatile and inflammable. They turn into gas at room temper- ature. Hence, they catch fire easily and may cause fire accidents. Q2. Give an example of a good fuel. How do you choose that fuel? Explain. [Refer to TB page 120 Q4] A. Natural gas is an example of a good fuel. It is an ideal fuel because it: i. Does not leave ash. ii. Has high calorific value. iii. Burns with smokeless flame. iv. Readily available. v. Does not pollute the environment. Q3. The oil fires should not be sprayed with water. Why? [Refer to TB page 120 Q5] A. Oil being lighter floats on water and causes severe damage. So oil fire should be extin- guished by using substances called foamite. Or Water is heavier than the oil. So it sinks below the oil and oil keeps burning on the top and thus causes severe damage. So oil fire should be extinguished by using substances called foamite. Q4. What precautions are to be taken while pouring water on fire? [Refer to TB page 120 Q6] A. We should make sure that any electrical equipment is not on fire. Water is also not suitable for fires involving oil and petrol. SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 35

Q5. Why a wick is not used in gas burners? [Refer to TB page 120 Q7] A. Kerosene oil and molten wax rise through the wick and become gas and form flames. A fuel catches fire immediately if it is in the form of gas. So wick is not used as a gas burner. Q6. Water is not used to control fires involving electrical equipment. Why? [Refer to TB page 120 Q8] A. The risk of electrical shock is too high if water is used as a fire extinguisher in the case of electrical fires as impure water is good conductor of electricity. So carbon dioxide or carbon tetrachloride are used to control fires involving electrical equipment. Q7. It is difficult to burn a heap of green leaves but not heap of dry leaves? Explain why. [Refer to TB page 121 Q1, Try These] A. The ignition temperature of green leaves is more that of dry leaves, because green leaves have more water content. The substances which have low ignition temperatures can catch fire easily. So it is easier to burn a heap of dry leaves. 2.5 Asking Questions and Making Hypothesis Q1. Give supportive arguments for both the statements [Refer to TB page 120 Q9] (1) fire is useful. (2) fire is harmful. A. Fire is useful: It is necessary for various daily activities like cooking food, giving light. Fire is utilized in making different types of articles with metals and plastics. The heat energy produced from fire of coal used to produce electricity. Fire is harmful: Fire liberates smoke and cause pollution. Wildfire in forests causes damage to living organisms in the forest. It can burn huts, hay stacks etc., and can cause much destruction. Q2. In a few years, the fuels on earth are will be exhausted. Think, what would happen to human civilization? [Refer to TB page 121 Q2, Try These] SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 36

A. Fossil fuels are going to be exhausted in future. Humans have to depend upon natural source of energy like solar, wind and hydroelectricity. Human civilization may regress. If there were no fossil fuels, human life in this world would be significantly different. The earth contains fossil fuels such as coal, petroleum and natural gas. They create elec- trical power, heat houses, power vehicles and transform the environment. Our world is dominated by fossil fuels. They make our electricity, heat our homes, power our cars and are changing our climate. The consequences of lack of fuel – 1. Without fossil fuel life would be complicated and very difficult. 2. There would be no fuel for cooking. 3. There would be no fuel for transport. There would be no fuel for any machinery. 4. There would be no fuel for electricity. Q3. Use of more fuels in our daily life causes air pollution and is harmful to human being and other life on earth. Suggest some remedies to avoid this. [Refer to TB page 121 Q3, Try These] A. Burning of carbon containing fuels releases ash and other harmful pollutants. Combus- tion of fuels adds CO2 into the environment leading to greenhouse effect which causes global warming. Wind energy, tidal energy, solar energy, etc. release fewer pollutants. If the distance is less, it is better to go by bicycle. Increase the use of unleaded petrol and using catalytic converter in vehicles. Q4. Let us assume that you are on the moon. If you try to focus sunlight on a paper using magnifying glass, does the paper catch fire? or not? Why? [Refer to TB page 120 Q11] A. No, it does not catch fire. The three conditions required to produce fire are: i. Presence of oxygen ii. Ignition temperature iii. Presence of combustion material On moon there is no oxygen. Hence it does not catch fire. SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 37

2.6 Experimentation and Field Investigation Q1. Can you heat water in a paper vessel? How is it possible? [Refer to TB page 120 Q12] A. Yes, we can heat water in a paper vessel. The heat supplied to the paper cup is trans- ferred to water by conduction. So in the presence of water the ignition temperature of the cup is not reached. Hence the paper does not burn, only the water is heated. Q2. “Is combustion possible without the supply of oxygen?\" Discuss with your teacher. [Refer to TB page 120 Q13] A. No, combustion is not possible without oxygen. Burn a candle. Now put a beaker inverted on to it. You will see that the flame flickers and then it will extinguish. As the inverted beaker has cut off the supply of oxygen the flame was extinguished. This experiment proves that oxygen is necessary for combustion. Q3. Explain giving reasons: In which of the following situations water will get heated in a shorter time? [Refer to TB page 121 Q14] a) Srikar kept the water beaker near the wick in the yellow part of a candle flame. b) Sonu kept water beaker in the outer most part of the flame. A. Water beaker (Sonu’s) which is in the outer most part of the flame will be heated in a shorter time. Because in the outer zone complete combustion takes place and it is the hottest zone. 2.7 Information Skills and Projects Q1. List the ways adopted by fire fighters to combat fires. [Refer to TB page 120 Q15] A. Using water: Water is the most common fire extinguisher. It can be used only when materials like wood, paper are on fire. We cannot use water if electrical equipments, oil and petroleum are on fire. Using carbon dioxide: Carbon dioxide is the best fire extinguisher used to put out the fires caused by oil, petrol and electrical equipment. CO2 is heavier than air and it covers the fire. Hence it cuts off the oxygen supply. SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 38

Q2. Collect information available on different fuels. Find out the cost per kg. Compare the cost with calorific value. Prepare a report on that. [Refer to TB page 121 Q16] A. S.No. NAME OF THE COST PER CALORIFIC FUEL kg VALUE 1 Petrol Rs.80/L 45000 kJ/kg 2 Diesel Rs.58/L 45000 kJ/kg 3 Kerosene Rs.20/L 45000 kJ/kg 4 LPG Rs. 67/kg 55000 kJ/kg 5 CNG Rs. 49/kg 50000 kJ/kg REPORT: The calorific value of petrol is more and cost is also high. The calorific value of kerosene is high and cost is low. The cost of fuel may change with time and place. Q3. Collect the information about annual fuel consumption in different parts of the world. How many years more the fossil fuels last? Make a poster with this information and issue an appeal to save fuel. [Refer to TB page 121 Q5, Try These] A. Students’ activity. Suggestions for poster – i. Save fuel save future. ii. Save fuel prevent energy crisis. iii. Energy saver saves environment. According to the article Regional energy use (kWh/capita &TWh) and growth 1990–2008 (%) ”If the fuel is used at this rate it is going to exhaust within 150 years.” SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 39

2.8 Communication Through Drawing and Model Making Q1. Draw the diagram of candle flame and label all the zones. [Refer to TB page 121 Q17] A. SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 40

2.9 Application to Daily Life, Concern to Bio Diversity Q1. How do you organize your daily works with fuels to conserve bio–diversity? [Refer to TB page 121 Q19] A. Fossil fuels burn and release pollutant gases and ash into the atmosphere. Instead of fossil fuels we should use renewable sources like solar energy, wind energy and other renewable sources. They do not pollute the environment. Due to fossil fuels some species are disappearing. Using bicycles for short distances and usage of renewable resources make the environment pollutant free. Q2. How do you feel about “Fuels have become a part of human life”? [Refer to TB page 121 Q20] A. Without fuels there is no human life. i. To cook food we are using fuels. ii. We are getting energy from food. iii. Electric power makes us feel comfortable. iv. We are using fuels in automobiles. So, it is appropriate to say that fuels have become a part of human life. —— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. Fill in the blanks. [Refer to Session 8.2 ] (i) Calorific value is measured in . (ii) When wood or paper is on fire, is used as fire extinguisher. CHAPTER 8. COMBUSTION, FUELS AND FLAME 41

2. State true or false. [Refer to Session 8.1 ] (i) Magnesium is a non–combustible material. [ ] (ii) Combustible substances have to be initially heated to catch fire. [ ] (iii) Substances which have very low ignition temperature and easily catch fire are called low–combustible substances. [] (iv) LPG is an inflammable substance. [] (v) When a substance burns rapidly and produces heat and light, it is called spontaneous combustion. [] 3. Fill in the blanks. [Refer to Session 8.1 ] (i) and are produced when materials are burnt in air. (ii) A chemical process in which a material reacts with oxygen to generate heat is called . (iii) Materials that burn when brought near flame are called materials. (iv) Materials that do not burn are called materials. (v) is needed to burn a material. CHAPTER 8. COMBUSTION, FUELS AND FLAME 42

Short Answer Type Questions 4. Answer the following questions in 3-4 sentences. (i) [(Session 8.2)] A wax candle burns with a yellow flame whereas domestic gas burns with a blue flame. Why? (ii) [(Session 8.2)] What are the three things required to keep a fire going? (iii) [(Session 8.2)] Oil fires should not be sprayed with water. Why? 5. Answer the following questions in 3-4 sentences. (i) [(Session 8.1)] Define combustible and non–combustible materials. (ii) [(Session 8.1)] What happens when you cover a burning candle with a glass tumbler? What do you infer? (iii) [(Session 8.1)] What is LPG? Why is it an inflammable substance? (iv) [(Session 8.1)] Classify the following as combustible or non–combustible materials: dry wood, magnesium ribbon, glass. (v) [(Session 8.1)] Define the terms inflammable substance, spontaneous combustion and rapid combustion. Long Answer Type Questions 6. Answer the following questions in 6-8 sentences. (i) [(Session 8.2)] What are the various zones of a candle flame? Which zone of flame does a goldsmith use for melting gold and silver? Why? (ii) [(Session 8.2)] Explain how CO2 is able to control fires. 7. Answer the following questions in 6-8 sentences. (i) [(Session 8.1)] What is calorific value? What are the conditions required to produce fire? CHAPTER 8. COMBUSTION, FUELS AND FLAME 43

AS2-Asking questions and making hypothesis Short Answer Type Questions 8. Answer the following questions in 3-4 sentences. (i) [(Session 8.2)] Sahana said phosphorus is preserved in water. Why do you think it is preserved in water? 9. Answer the following questions in 3-4 sentences. (i) [(Session 8.1)] Nishanth saw a magic trick today. The magician took a paper cup with water, and put it on a flame. But it did not burn. Why? Long Answer Type Questions 10. Answer the following questions in 6-8 sentences. (i) [(Session 8.1)] Sonam learnt that there are three things required to keep a fire go- ing. She wondered if fire could be controlled if these factors are controlled. What do you think? Explain. AS3-Experimentation and field investigation Short Answer Type Questions 11. Answer the following questions in 3-4 sentences. (i) [(Session 8.1)] Name the products formed when a candle burns in air. (ii) [(Session 8.1)] In the experiment to prove that oxygen is required for burning, explain how oxygen is liberated. Long Answer Type Questions 12. Answer the following questions in 6-8 sentences. (i) [(Session 8.1)] How will you show that oxygen helps in burning? CHAPTER 8. COMBUSTION, FUELS AND FLAME 44

AS4-Information skills and projects Very Short Answer Type Questions 13. Answer the following questions in one sentence. [Refer to Session 8.2 ] (i) Here are some fuels. Arrange them in the following table. LPG, Coal, Petrol, Charcoal, Gasoline, CNG, Diesel, Wood, Natural gas. Solid Liquid Gas 14. Answer the following questions in one sentence. [Refer to Session 8.1 ] (i) Complete the table. Material Type of material (combustible Sand /non–combustible) Non–combustible Petrol Wood Combustible Clay Long Answer Type Questions 15. Answer the following questions in 6-8 sentences. (i) [(Session 8.2)] Collect information on the fire accidents in the major cities of India. Prepare a report on that. CHAPTER 8. COMBUSTION, FUELS AND FLAME 45

AS5-Communication through drawing and model making Short Answer Type Questions 16. Answer the following question. (i) [(Session 8.2)] Mark hottest part, moderately hot and less hot part in a flame. Long Answer Type Questions 17. Answer the following question. (i) [(Session 8.2)] Draw a neatly labeled diagram of the flame of a candle and answer the following questions. a) Which zone is luminous? b) Which zone is called the zone of complete combustion? AS6-Appreciation and aesthetic sense, Values Short Answer Type Questions 18. Answer the following questions in 3-4 sentences. (i) [(Session 8.2)] How do you appreciate the contribution of fossil fuel to modern soci- ety? AS7-Application to daily life, concern to bio diversity Short Answer Type Questions 19. Answer the following questions in 3-4 sentences. (i) [(Session 8.2)] Can the process of rusting be called combustion? What about diges- tion? CHAPTER 8. COMBUSTION, FUELS AND FLAME 46

Objective Questions AS1-Conceptual Understanding 20. Choose the correct answer. (i) There are flame zones in structure of a flame. (A) 1 (B) 2 (C) 3 (D) 4 (ii) Which of the following does not burn with flame? (A) Candle (B) Charcoal (C)Domestic gas (D)Wick of kerosene stove (iii) Calorific value of a fuel is calculated as the amount of heat liberated per of fuel. (A) 1 gram (B) 100 grams (C)10 kilogram (D)1 kilogram (iv) The following substance is present in fire extinguishers. (A) Water (B) Nitrogen (C)Carbon dioxide (D)Carbon monoxide (v) zone of flame is used by goldsmith. (A) Inner zone (B) Outer zone (C)Middle zone (D)Blue zone (vi) Burning a material in the presence of air is called . (A) evaporation (B) sedimentation (C) combustion (D) combination CHAPTER 8. COMBUSTION, FUELS AND FLAME 47

(vii) The lowest temperatre at which a substance catches fire is called ___________. (A) fuel temperature (B) melting temperature (C)ignition temperature (D)normal temperature (viii) is essential for combustion to take place. (A) Carbon dioxide (B) Ozone (C) Hydrogen kJ/ kg. (D) Oxygen (ix) Calorific value of petrol is (B) 17,000 (A) 6000 (C) 25,000 (D) 45,000 AS2-Asking questions and making hypothesis 21. Choose the correct answer. (i) In which zone of the candle flame, wax does not burn? (A) White Zone (B) Dark Zone (C)Yellow Zone (D)Red Zone AS3-Experimentation and field investigation 22. Choose the correct answer. (i) Fuel must be heated to its before it starts burning. (A) normal temperature (B) high temperature (C)ignition temperature (D)any temperature AS4-Information skills and projects 23. Choose the correct answer. (i) A liquid fuel used in home is . CHAPTER 8. COMBUSTION, FUELS AND FLAME 48