202110241-TRIUMPH-STUDENT-WORKBOOK-PHYSICAL_SCIENCE-G08-PART1

A. Name of the fuel Cost of the fuel as Pollutants on today (In Rs) liberated Diesel/petrol 60.00/83.00 Diesel has significantly lower CO2 emissions than petrol, but has higher NO2 , particulate emissions, carbon monoxide, carbon dioxide, hydrocarbons and sulphur dioxide. CNG 52 CNG has much lower CO2, particulate emissions, carbon monoxide and sulphur dioxide. Note: Petrol, diesel and CNG rates vary with time and place. Q2. [AS4] Choose five families in your neighbourhood, collect the information about the mea- sures that they adopt to conserve energy resources in transport and cooking. [Refer to TB page 106 Q3] SESSION 2. COAL, PETROLEUM AND NATURAL GAS 199

Name of Number of No. of Amount Amount the family members vehicles spent for spent for fuel per cooking in the using purpose family month A. Students’ activity. Objective Questions (1) Which one of the following material is used for making shoe polish? (Pg 106; TB Q 3) (A) Paraffin wax (B) Petrol (C) Diesel (D)Lubricating oil Correct Answer: A SESSION 2. COAL, PETROLEUM AND NATURAL GAS 200

(2) Which one of the following is less polluting fuel ? (Pg 105; TB Q 1) (A) Natural gas (B) Coal gas (C) Kerosene (D) Petrol Correct Answer: A .(Pg 105; TB Q 2) (3) The main constituent of coal is (B) Oxygen (D) Water (A) Carbon (C) Air Correct Answer: A (4) Which one of the following is not a fossil fuel? ( Pg 106; TB Q 4) (A) Coal (B) Petroleum (C) Charcoal (D)Natural gas Correct Answer: C (5) Which one of the following is known as liquid gold? ( Pg 106; TB Q 5) (A) Kerosene (B) Diesel (C) Petroleum (D)Paraffin wax Correct Answer: C —— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. Fill in the blanks. as fuel in the olden days, now is being [Refer to Session 7.2 ] (i) Food was cooked using used. (ii) Petroleum is also called due to its great commercial importance. (iii) The steam engine which used .................. was invented during the industrial revolution. CHAPTER 7. COAL AND PETROLEUM 201

(iv) Now a days, 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. 2. State true or false. [Refer to Session 7.1 ] (i) Carbon dioxide is a major cause for global warming. [] 3. 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? CHAPTER 7. COAL AND PETROLEUM 202

Short Answer Type Questions 4. Answer the following questions in 3-4 sentences. (i) [(Session 7.2)] What are petrochemicals? Where are they used? 5. Answer the following questions in 3-4 sentences. (i) [(Session 7.1)] Why should people look for alternative sources to fossil fuels? CHAPTER 7. COAL AND PETROLEUM 203

Long Answer Type Questions 6. 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 204 Short Answer Type Questions CHAPTER 7. COAL AND PETROLEUM

7. 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? CHAPTER 7. COAL AND PETROLEUM 205

AS3-Experimentation and field investigation Long Answer Type Questions 8. 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. AS4-Information skills and projects 206 Very Short Answer Type Questions CHAPTER 7. COAL AND PETROLEUM

9. 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 Metals Plastics 10. Answer the following questions in one sentence. [Refer to Session 7.1 ] (i) Collect information on the presence of alternate sources of energy in India. Write where solar energy is used and how much of the power demand is met by these three renewable sources. CHAPTER 7. COAL AND PETROLEUM 207

Long Answer Type Questions 11. Answer the following questions in 6-8 sentences. (i) [(Session 7.2)] Mention the uses of petrochemicals in various sectors in a table. AS5-Communication through drawing and model making Short Answer Type Questions 12. 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. CHAPTER 7. COAL AND PETROLEUM 208

Long Answer Type Questions 13. Answer the following question. (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. CHAPTER 7. COAL AND PETROLEUM 209

AS6-Appreciation and aesthetic sense, Values Short Answer Type Questions 14. Answer the following questions in 3-4 sentences. (i) [(Session 7.2)] Give some instances where we misuse energy resources. What are its consequences? CHAPTER 7. COAL AND PETROLEUM 210

AS7-Application to daily life, concern to bio diversity Short Answer Type Questions 15. 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)] Why has the price of petrol increased dramatically in the last 20 years? CHAPTER 7. COAL AND PETROLEUM 211

(iii) [(Session 7.2)] What are the environmental and health concerns regarding the use of fossil fuels? CHAPTER 7. COAL AND PETROLEUM 212

Objective Questions AS1-Conceptual Understanding 16. 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 (B) metals (A) gases (C) energy (D)fossil fuels (B) Compact National Gas (iii) CNG stands for . (A) Compressed Natural gas (C)Compound Natural Gas (D)Coated Natural Gas (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) The ‘almost pure form of carbon’ is used in . CHAPTER 7. COAL AND PETROLEUM 213

(A) pesticides (B) synthetic dyes (C) lighting (D)extraction of metals (viii) The slow process of conversion of dead vegetation in to coal is called–––––––. (A) oxidation (B) hybridization (C) carbonization (D) hydroxylation (ix) . gas is obtained during the processing of coal to get coke. (A) Coal (B) LPG (C) CNG (D)None of the above AS3-Experimentation and field investigation 17. Choose the correct answer. (i) is obtained by mixing the mineral kaolinite with water. (A) Plastics (B) Glass (C) Clay (D) Wood (ii) Petroleum is separated into various components by . (A) sedimentation (B) filtration (C) centrifugation (D)fractional distillation AS4-Information skills and projects 18. Choose the correct answer. (i) Vaseline is made from . (A) diesel (B) petrol (C) kerosene (D)paraffin wax (ii) Petroleum is also known as . CHAPTER 7. COAL AND PETROLEUM 214

(A) black gold (B) liquid treasure (C)black magic (D)liquid platinum AS6-Appreciation and aesthetic sense, Values 19. 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 products called ––––––––––––. (A) algae (B) planktons (C) azolla (D) azotobacter AS7-Application to daily life, concern to bio diversity 20. 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 215

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... 216

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... 217

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 Reflection on Concepts Q1. [AS1] Give four examples of combustible materials. [Refer to TB page 117 Q1] A. Petrol, kerosene, coal, wood. Q2. [AS1] Why should not we store spirit or petrol near our living place? [Refer to TB page 117 Q2] 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. 1.5 Application of Concepts Q1. [AS7] Where do you find spontaneous and rapid combustion in your daily life? [Refer to TB page 117 Q4] 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. 1.6 Higher Order Thinking Skills Q1. [AS1] Why is Phosphorus preserved in water? [Refer to TB page 118 Q1] A. Phosphorous is a combustible material that catches fire spontaneously when it comes in contact with air. So, it is stored in water, to prevent its contact with air and also to prevent it to reach its ignition temperature. Q2. [AS2] Is there any procedure to prove that oxygen is needed for burning? [Refer to TB page 118 Q3] SESSION 1. COMBUSTION, TYPES OF COMBUSTION AND IGNITION TE... 218

A. Yes, there is an activity that we can conduct to prove that oxygen is needed for burning. AIM: To prove that oxygen is needed for burning. MATERIALS REQUIRED: Test tube, test tube holder, spirit lamp, match box, incense stick (agarbatti), potassium permanganate(KMnO4 ). PROCEDURE: • Light an incense stick and let it burn for 10 seconds then put out the flame and keep it aside. • Take KMnO4 in a test tube. Hold the test tube with a test tube holder and heat it over the flame of the spirit lamp. • Oxygen is released on heating of Potassium Permanganate. • 2KMnO4 → K2 MnO4 + MnO2 +O2 • Insert the agarbatti with the burning stub into the test tube as shown. Observation : Agarbatti started burning because of the oxygen liberated by Potassium Permanganate. It does not burn when kept aside due to insufficient amount of oxygen. 1.7 Suggested Experiments Q1. [AS3] Conduct an experiment for testing the necessity of air to burning. [Refer to TB page 118 Q1] SESSION 1. COMBUSTION, TYPES OF COMBUSTION AND IGNITION TE... 219

A. Take a small burning candle and put it on a table. Invert a glass tumbler over it. The candle continues to burn for some time. Then flickers and finally flame goes off. Remove the tumbler and again light the candle. Put the tumbler back over the candle. When the candle flame begins to flicker, remove the tumbler and observe carefully. We observe that putting the glass tumbler over the candle cuts off the supply of air and the candle flame goes off. This experiment proves that air is needed to burn a material. Q2. [AS3] Conduct an experiment to prove that Oxygen helps in burning. [Refer to TB page 118 Q2] A. AIM: To prove that oxygen helps in burning. MATERIALS REQUIRED: Test tube, test tube holder, spirit lamp, match box, incense stick(agarbatti), potassium permanganate(KMnO4 ). PROCEDURE: • Light an incense stick and let it burn for 10 seconds then put out the flame and keep it aside. • Take KMnO4 in a test tube. Hold the test tube with a test tube holder and heat it over the flame of the spirit lamp. • Oxygen is released on heating of Potassium Permanganate. • 2KMnO4 → K2 MnO4 + MnO2 +O2 • Insert the agarbatti with the burning stub into the test tube as shown. Observation : Agarbatti started burning because of the oxygen liberated by KMnO4 . It does not burn when kept aside due to insufficient amount of oxygen. SESSION 1. COMBUSTION, TYPES OF COMBUSTION AND IGNITION TE... 220

This experiment proves that Oxygen helps in burning. Q3. [AS3] Can you heat water in a paper vessel? How is it possible? Conduct an experiment to understand the Ignition temperature. [Refer to TB page 118 Q3] 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. Refer Text Book activity - 4 (Page -112) to understand Ignition Temperature. Objective Questions (1) The gas needed for combustion among the following. ( Pg 118; TB Q 1) (A) Argon (B) Oxygen (C)Carbon dioxide (D) Hydrogen Correct Answer: B (2) The lowest temperature at which a substance catches fire is called its . (Pg 118; TB Q 2) (A) Ignition temperature (B) Maximum temperature (C)Room temperature (D)Normal temperature Correct Answer: A .(Pg118; TB Q 4) (3) Spirit and petroleum turns into gas at (A) Room temperature (B) Ignition temperature (C)Maximum temperature (D)Normal temperature Correct Answer: A (4) The type of combustion in which materials suddenly burns into flames without the application of any external agent is called .(Pg 118; TB Q5) (A) Rapid combustion (B) Slow combustion (C)Spontaneous combustion (D) Explosion Correct Answer: C SESSION 1. COMBUSTION, TYPES OF COMBUSTION AND IGNITION TE... 221

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 222

3. Fire 4. Fire Control SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 223

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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 non polar 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. 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 Reflection on Concepts Q1. [AS1] Water is not used to control fires involving electrical equipment. Why? [Refer to TB page 117 Q4] 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. Q2. [AS2] The oil fires should not be sprayed with water. Why? [Refer to TB page 117 Q3] A. 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. SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 225

Q3. [AS1] List the ways adopted by fire fighters to combat fires. [Refer to TB page 117 Q5] 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 are on fire or if 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 . Q4. [AS5] Draw the diagram of a candle flame and label all the zones. [Refer to TB page 117 Q6] A. 2.5 Application of Concepts Q1. [AS1] Give an example of good fuel. How do you choose that fuel? Explain. [Refer to TB page 117 Q2] A. Natural gas is an example for good fuel. It is an ideal fuel because it: i. Does not leave ash. ii. Has high calorific value. iii. Burns with smoke less flame. iv. Readily available. v. Does not pollute the environment. SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 226

Q2. [AS1] What precautions are to be taken while pouring water on fire? [Refer to TB page 117 Q1] A. Water works only when things like wood and paper are on fire. If electrical equipment is on fire, water may conduct electricity and harm those trying to douse the fire. Water is also not suitable for fires involving oil and petrol. So we should not pour water on fire caused by electrical appliances and on oil fires. Q3. [AS1] Why the fire brigade start the work by putting off the electric mains? [Refer to TB page 117 Q5] A. The most common fire extinguisher used by the fire brigade is water. The fire brigade shuts off the electric mains because water is fairly a good conductor of electricity. If the water that conducts electricity comes in contact with any humans, it could turn out to be fatal. Q4. [AS2] Why is it difficult to burn a heap of green leaves but not heap of dry leaves? Explain. [Refer to TB page 117 Q3] A. The ignition temperature of green leaves is more that of dry leaves, because green leaves have more water content. The substance which have low ignition can catch fire easily. So it is easier to burn a heap of dry leaves. Q5. [AS3] Explain giving reasons in which of the following situations water will get heated in a shorter time? [Refer to TB page 117 Q6] a) Srikar kept the water beaker near the wick in the yellow part of the candle flame. b) Sonu kept the 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. 2.6 Higher Order Thinking Skills Q1. [AS2] In a few years, fuels on earth are going to be exhausted. Think what would happen to human civilization? [Refer to TB page 118 Q4] SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 227

A. Fossil fuels are going to be exhausted in future. Humans have to depend upon natural source of energy like solar energy, wind energy and hydroelectricity. Human civilization may retrogress. If there were no fossil fuels, human life in this world would be signifi- cantly different. The earth contains fossil fuels such as coal, petroleum and natural gas. These fuels are used to generate electrical power, to run the vehicles and machines, to cook food, etc. Our world is dominated by fossil fuels. Without fossil fuels life would be complicated and very difficult. 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. Q2. [AS7] How do you feel about “Fuels have become a part of human life?” [Refer to TB page 118 Q2] A. Without fuels there is no human life. i. To cook food we use fuel. ii. We use fuel in automobiles. iii. Fuels are used to generate electricity. So, we say that fuels have become a part of human life. 2.7 Suggested Projects Q1. [AS4] Collect information available on different fuels. Find out the cost per kg and com- pare the cost with the calorific value. Prepare a report on that. [Refer to TB page 118 Q2] SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 228

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. Q2. [AS4] Collect the information about annual fuel consumption in different parts of the world. Comment on as to how many years the fuels are going to serve us. Make a poster with this information and issue an appeal to save fuel. [Refer to TB page 118 Q3] 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 229

Q3. [AS7] List out the different fuels that are used in your daily life and classify them into solids, liquids and gases. [Refer to TB page 118 Q1] A. Students’ activity. . ( Pg 118;Q3) (B) Newtons/Kg Objective Questions (D) Kilojouls/gram (1) The units of calorific value is (A) Newtons/grams (C) Kilojouls/kg Correct Answer: C SESSION 2. FUELS, FLAME AND STRUCTURE OF A FLAME 230

—— CCE Based Practice Questions —— AS1-Conceptual Understanding [ ] Very Short Answer Type Questions [ ] 1. 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. [] 2. 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 231

3. 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. Short Answer Type Questions 4. Answer the following questions in 3-4 sentences. (i) [(Session 8.1)] What is LPG? Why is it an inflammable substance? 5. Answer the following questions in 3-4 sentences. (i) [(Session 8.2)] Oil fires should not be sprayed with water. Why? CHAPTER 8. COMBUSTION, FUELS AND FLAME 232

Long Answer Type Questions 6. 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 233

AS2-Asking questions and making hypothesis Short Answer Type Questions 7. 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? 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? AS3-Experimentation and field investigation 234 Long Answer Type Questions CHAPTER 8. COMBUSTION, FUELS AND FLAME

9. 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 235

AS4-Information skills and projects Very Short Answer Type Questions 10. Answer the following questions in one sentence. [Refer to Session 8.1 ] (i) Complete the table. Material Type of material(combustible / Sand non–combustible) Petrol Non–combustible Wood Clay Combustible 11. 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. CHAPTER 8. COMBUSTION, FUELS AND FLAME 236

Solid Liquid Gas Long Answer Type Questions 12. 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 237

AS5-Communication through drawing and model making Short Answer Type Questions 13. Answer the following question. (i) [(Session 8.2)] Draw and mark hottest part, moderately hot and less hot part in a flame. Long Answer Type Questions 14. Answer the following questions in 6-8 sentences. (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? CHAPTER 8. COMBUSTION, FUELS AND FLAME 238

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AS6-Appreciation and aesthetic sense, Values Short Answer Type Questions 15. 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 16. 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 240

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Objective Questions AS1-Conceptual Understanding 17. 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) of flame is used by goldsmith. (B) Outer zone (A) Inner 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 (vii) The lowest temperature at which a substance catches fire is called . CHAPTER 8. COMBUSTION, FUELS AND FLAME 242

(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 18. 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 19. 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 20. Choose the correct answer. (i) A liquid fuel used in home is . CHAPTER 8. COMBUSTION, FUELS AND FLAME 243

(A) CNG (B) LPG (C) PGL (D) NCG AS6-Appreciation and aesthetic sense, Values 21. Choose the correct answer. (i) is an excellent fire extinguisher. (B) Hydrogen dioxide (A) Oxygen (C)Carbon dioxide (D) Nitrogen AS7-Application to daily life, concern to bio diversity 22. Choose the correct answer. (i) is a source of both light and usable heat. (A) Candle (B) Tube light (C) Bulb (D) CFL CHAPTER 8. COMBUSTION, FUELS AND FLAME 244

9. ELECTRICAL CONDUCTIVITY OF LIQUIDS SESSION 1 INTRODUCTION AND ELECTRICAL CONDUCTIVITY OF LIQUIDS 1.1 Mind Map 1.2 Terminology i. Good conductors – A good conductor of electricity allows an easy flow of electric current through them. E.g., Copper, Silver etc. ii. Poor conductors – Poor conductors do not allow current to pass through them. E.g.,Rubber, Plastic etc. iii. Circuit – In electronics, a circuit is a path between two or more points along which an electrical current can be carried. iv. Tester – Tester is a simple piece of electronic test equipment used to determine the presence or absence of an electric voltage in a piece of equipment under test. SESSION 1. INTRODUCTION AND ELECTRICAL CONDUCTIVITY OF LIQ... 245

v. Dry cell – A voltage–generating cell having an electrolyte in the form of moist paste. 1.3 Key Concepts i. Conductors of electricity are those materials that allow electricity to pass through them. ii. Insulators (poor conductors) of electricity are those materials that do not allow elec- tricity to pass through them. iii. Many materials around us are conductors and some are poor conductors. iv. Some liquids are good conductors of electricity and some are poor conductors. v. Pure water does not allow the current to pass through. 1.4 Reflection on Concepts Q1. [AS1] Give examples for good conductors, both solid and liquid. [Refer to TB page 129 Q1] A. Good solid conductors: Copper, silver, iron, aluminium, graphite etc. Good liquid conductors: Drinking water, lemon juice, mercury, acid solution etc. Q2. [AS1] Give examples for poor conductors, both solid and liquid. [Refer to TB page 129 Q2] A. Poor solid conductors: Plastic, rubber, paper etc. Poor liquid conductors: Distilled water, honey, oil etc. Q3. [AS1] Give two examples for electrolyte. [Refer to TB page 129 Q3] A. Sodium chloride and Nitric Acid. 1.5 Application of Concepts Q1. [AS1] What do you add to distilled water to make it conduct electricity? [Refer to TB page 130 Q2] A. We can add salt to distilled water to make it conduct electricity. SESSION 1. INTRODUCTION AND ELECTRICAL CONDUCTIVITY OF LIQ... 246

Q2. [AS2] Kavya observed that a discharged dry cell which was kept in sunlight by her father for few hours got the ability to glow LEDs. She got many doubts and questions to ask. Can you guess those questions or doubts? [Refer to TB page 130 Q3] A. i. How could the bulb glow? ii. Which energy helped the bulb to glow? iii. How could the solar energy effect the cell? iv. How was electrical energy obtained? v. Can this be a repeated action? Q3. [AS7] Collect information and make a list of good conductors and bad conductors. How do you use this information in your daily life? [Refer to TB page 130 Q5] A. Good conductors are the ones that allow electricity to pass through them easily. A list of good conductors are silver, copper, gold, aluminium, magnesium, tungsten, nickel, iron. Bad conductors are the ones that does not allow the electricity to flow through them. A list of bad conductors are plastic, wood, wool, silk, paper etc. In daily life, we use copper for conducting electricity. All our electrical appliances such as fans, ovens, iron box etc need good conductors of electricity to work. At the same time, the materials such as copper which conduct electricity should not be in human contact which is enabled by insulating the same with bad conductors of electricity like plastic, wood etc. 1.6 Suggested Experiments Q1. [AS3] Conduct an experiment for testing the electric conductivity of liquids. [Refer to TB page 130 Q2] A. Aim : To test electrical conductivity of a liquid. Materials required: An LED, dry cell, metal pins, rubber cap of injection bottle and wires for making connections. SESSION 1. INTRODUCTION AND ELECTRICAL CONDUCTIVITY OF LIQ... 247

i. Take an LED, dry cell, metal pins, rubber cap of injection bottle and wires for making connections. ii. Set up an electric circuit as shown in the figure. iii. See that the two metal pins, pass through the cap should have a very small gap (around 2 mm) between them so that the pins are fairly closer but not touching each other. iv. The LED should not glow when pins are separated by a small distance. v. Now, join the free ends of the pins together by pressing them for a moment and make sure that the LED glows. vi. Release the pins. When they get separated, the LED should not glow. This acts as a tester. vii. Fill the rubber cap with different liquids like distilled water, drinking water, coconut oil, kerosene, lemon juice, mustard oil, sugar solution etc. one after another and in each case check whether the LED glows or not. viii. Note down your observations in table. SESSION 1. INTRODUCTION AND ELECTRICAL CONDUCTIVITY OF LIQ... 248