Answer. The cooking oil all of a sudden caught fire, he poured water to extinguish the fire. Here we have given NCERT Exemplar Class 8 Science Chapter 6 Combustion and Flame. A chemical process in which a substance reacts with oxygen to give off heat. 55000 kJ/kg. * Even though halon is widely used, EPA legislation is phasing it out of use in favor of agents less harmful to the environment. (c) Kerosene (d) Hydrogen gas In jar B, the candle remains lighted for a longer time because oxygen is a supporter of combustion. (c) Forest fires are not due to cutting of trees. Ignition 5. Carbon Dioxide extinguishers are filled with non-flammable carbon dioxide gas under extreme pressure. 2.Non-combustible — chalk, stone, iron rod, copper coin, glass. That means it should produce large amount , of heat per unit mass. Write in brief about the reasons of forest fires. (c) cover the person with a woollen blanket Carbon dioxide fire extinguishing systems are useful in protecting against fire hazards when an inert, electrically nonconductive, three-dimensional gas is essential or desirable and where clean up from the agent must be minimal. (a) throw water on the clothes The most common fire extinguisher. The use of CNG as fuel in automobiles has reduced air pollution In big cities. 18 Two glass jars A and B ajre filled with carbon dioxide and oxygen gases respectively. 8 The substance expected to have the highest ignition temperature out of the following is 7 If a person’s clothes catch fire, the best way to extinguish the fire is to Fire happens when three things are in the same place at the same time: ... A foam extinguisher, on the other hand, works a bit more like a carbon dioxide extinguisher when the nozzle is open: the water and foaming solution swirl together in the nozzle, producing a much bigger volume of foam than the volume of the can itself. is called combustion. 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CO2 is clean, non-corrosive and leaves no residue on expensive computers and electronic equipment. Question. Carbon dioxide, ordinary(BC-rated)dry chemical, multi-purpose dry chemical and halon* fire extinguishers may be used to fight Class C fires. Question. (a) Iron nail (b) Glass (c) Stone piece (d) Wood A carbon dioxide (CO 2) fire extinguisher is a portable, active fire protection device that works by expelling carbon dioxide onto a fire.It works by displacing the oxygen the fire relies upon to continue burning, and it is primarily used to extinguish fires in which the source of … Question. p. 270 11.41. Question. Nitrogen cylinders that comply with 49 CFR 173.34(e)(15) may be hydrostatically tested every 10 … Different types of fire extinguishers are designed to fight different types of fire. True or False 18. (a) Diesel (b) Glass Fire Fighting Phases: Do not use water or halogenated hydrocarbons such as carbon tetrachloride. B. Answer. Anu should keep her test tube in the outermost zone or non-luminous zone of the flame because it is the hottest zone of a flame and has more temperature. Fire Extinguishers . (c) Carbon dioxide is an excellent fire extinguisher. Question. 1 A substance which reacts with oxygen giving heat is called a combustible substance. rammondal4556 rammondal4556 4 minutes ago Science Primary School Carbondioxide is needed for burning true or false 2 See answers rammondal4556 is waiting for your help. Reasons of forest fires are : CO2 extinguishers are … Add your answer and earn points. What types of fires can be extinguished with carbon dioxide (CO2) fire extinguishers? (c) Coal has the highest ignition temperature. (a) low ignition temperature and cannot catch fire easily c. Eight to … But sand or soil will not be available at that place. 1. 5. CNG will be more economical. (c) improper combustion of fuel (d) burning of copper vessel (b) Those substances which do not burn are called non-combustible substance. If you are at an office or shared network, you can ask the network administrator to run a scan across the network looking for misconfigured or infected devices. Fire extinguishers can be effectively used for both small and large fires. Iron wire will become red hot and glow. By doing this, the contact between fuel and oxygen is cut off and the flame will go off. (d) The substances which gave very …………..ignition temperature and can easily catch fire with a flame are called………….substances. Answer. If you have any query regarding NCERT Exemplar Class 8 Science Chapter 6 Combustion and Flame, drop a comment below and we will get back to you at the earliest. (d) Calorific value of wood is higher than that of coal. Answer. 12 In villages, people use wood as fuel because Use dry graphite, soda ash, powder sodium chloride or appropriate metal fire extinguishing powder. r. ect. The acronym for proper use of a fire extinguisher is: a. How does the CO2 put out a fire? Question. (b) In villages, people use wood as fuel because of its easy availability and low cost. It only glows on combustion. The carbon dioxide extinguisher pushes oxygen away from the fire and replaces it with carbon dioxide, which is inflammable and more dense than air. False. (i) At high temperature, sometimes dry grass catches fire which spreads throughout the forest. Since CO2 extinguishers are perfect for electrical fires, they are commonly found in offices or places where there is a lot of electrical devices. (iv) Calorific value of wood is higher than that of coal. Your IP: 148.251.76.241 (d) The calorific value of a fuel is expressed in the unit of kilojoule per kilogram (kJ/kg). d. All of the above Also write the false statements in their correct form. The three things to remember during a workplace fire emergency are stop, drop and roll. p. 270 11.40. They also put out Class B fires (flammable liquids, such as paint and petroleum). (c) cutting of trees (d) lightning strike 12. Question. fire extinguisher for the type of fire. Carbon Dioxide (CO2) and dry powder extinguishers prevent oxygen reaching the fire and extinguish it but they do not cool the burning material as water does, so if the powder gets blown away the fire can reignite. The correct matching is as given: (a) Cowdung cake (b) Petrol We have provided Combustion and Flame Class 8 Science MCQs Questions with Answers to help students understand the concept very well. The added advantage of C02 is that in most cases, it does not harm the electrical equipment. True or False: A portable fire extinguisher should only be used by trained employees. B. A comprehensive database of more than 15 fire extinguisher quizzes online, test your knowledge with fire extinguisher quiz questions. Class A fire extinguishers can be used on electrical fires False ( Class C) While using a fire extinguisher hold the extinguisher firmly and direct it to the middle or main part of the fire Carbon dioxide (chemical formula CO 2) is a colorless gas with a density about 53% higher than that of dry air. It is a solid fuel and produces smoke during combustion. The pressure in the cylinder is so great that when you use one of these extinguishers, bits of dry ice may shoot out the horn. Carbon Dioxide (CO2) Extinguishers. (a) kerosene (b) petrol (c) coal (d) alcohol The Kidde Pro 5 is a great choice if you’re looking for a reliable carbon dioxide fire extinguisher. Q. 2) True or False Dry Chemical fire extinguishers are good choices for electrical fires. Help her in this activity. Carbon dioxide can be used on Class B & C fires. (c) The lowest temperature at which a substance catches fire is called its …………… temperature. Question. 29 Cracker on ignition produces sound. 3 4 5. (d) Some substances on combustion produce thea and mafel. True. Question. (g) True. True or false? 6. If you are on a personal connection, like at home, you can run an anti-virus scan on your device to make sure it is not infected with malware. Answer. (e) calorific. 2. Fire extinguishers discharged/partly discharged should be thrown away. Foam extinguishers are primarily designed for use on Class B fires, they are also effective on Class A fires because they are predominantly water-based. The hot gases expand rapidly and cause an explosion (producing a loud sound). Combustion 4, Fuel 6. industries, CNG is used to run automobiles. You may need to download version 2.0 now from the Chrome Web Store. True or False? 22 State whether the following statements are True/False. Question. (b) high ignition temperature and can catch fire easily a. true b. false ref. These are used in . ... Give three reasons why you should decide NOT to use an extinguisher to fight a fire. 9. 3) A fire that is fueled by paper and combustibles is known as a Class "A" fire. Answer. a. true b. false ref. Two commonly used chemicals are effective in fighting these types of fires. It will not produce a flame. Question. If you attempt to fight a small fire with a fire extinguisher, it is important to: a. Petrol is used as a ………….. in automobiles. (f) Middle zone is the hottest zone of a flame. Note The lowest temperature at which a substance catches fire and starts burning, is called its ignition temperature. CNG will produce large amount of heat energy than petrol. One to two minutes. 4. (c) Carbon dioxide is an excellent fire extinguisher. Foam agents… Answer. (c) Due to incomplete combustion of fuel, copper vessel was getting blackened from outside. (c) Carbon dioxide is an excellent fire extinguisher. 19 Anu wants to boil water quickly in a test tube. (a) Air is necessary for combustion. Water is ineffective as it helps to spread the liquid and the fire. When they throw away lighted cigarettes in the forest. What is the proper way to use a Class BC, CO2 fire extinguisher? Label Colour: – Black Use for: – Flammable liquids, like paint and petrol – Electrical fires . Class B fires which involve flammable liquids and gases, solvents, oils, greases (excluding cooking oils/greases in depth) tars, oil-based paints and lacquers. (iii) Carbon dioxide is an excellent fire extinguisher. 5 The substance that does not burn with flame is Answer. Class A, B and C . So, Manu should have switched off the flame of the burner and put a lid on the frying pan. (b) When the clothes of a person catch …………the person is covered with a…………… to extinguish fire. Indicate whether the following statements are True or False. True False: Heat always flows from a higher temperature to a lower temperature. p. 270 11.39. Oxygen. 4.False, calorific value of coal is higher than that of wood. Since, the contact between the fuel and oxygen is cut off, so the fire can be controlled. They don't contain water and won't damage surrounding equipment like powder extinguishers. True 12 Class B fires can be extinguished with water, water based agents, and dry chemicals. An APW (water extinguisher) is safe to use on an electrical fire. Answer. C02 being heavier than oxygen, covers the fire like a blanket. Which type of extinguisher has a hard horn on the end of a flexible hose or metal arm? CO2 extinguishers are … Charcoal, chalk, stone, iron rod, copper coin, straw, cardboard, glass, paper, candle, wood. True or false 1 See answer learnerinfinitive is waiting for your help. When an extinguishing agent covers and cools the fire source, the fire loses its: a. (e) The amount of heat energy produced on complete combustion of 1 kg of a fuel is called its ficalroic value. Thus, fire can be controlled. Carbon Dioxide. Also, petrol is an inflammable substance, i.e. Question. True or False 18. You can recognize a CO2 extinguisher by its hard horn and lack of pressure gauge. Smoke detectors are not used in cargo and baggage compartments. 36 Although wood has a very high calorific value, we still discourage its use as a fuel. As the CO2 gas is expelled it turns into a cloud of dry ice, commonly referred to as "snow". (b) Slaas is a non-combustible material. Which one of the following is a combustible substance? Fire Extinguisher. 33 What are the three essential requirements to produce fire? We will prefer CNG (Compressed Natural Gas) because the calorific value of CNG is higher than that of petrol. Question. (vii) The friction of bamboos due to high wind velocity and rolling stones. (c) The………….. temperature at which a substance catches fire is called its…………..temperature. Water being heavier than oil sinks to bottom and hence, fire does not get controlled. (b) Magnesium is a non-combustible metal. They have For fires involving electrical equipment and inflammable materials like petrol, then carbon dioxide (C02)is the best extinguisher. When using a fire extinguisher you should use the PASS procedure. True or false learnerinfinitive learnerinfinitive 29.04.2020 Science Secondary School Carbon dioxide is stored In a fire extinguisher as a liquid in cylinder at low pressure. The gases produced are heated by the heat evolved in the reaction. It occurs naturally in Earth's atmosphere as a trace gas.The current concentration is about 0.04% (412 ppm) by volume, having risen from pre-industrial levels of 280 ppm. Carbon Dioxide is a heavy gas, commonly stored compressed in a cylinder for use as a fire extinguisher. True or False 17. True or False 20. Carbon dioxide is heavier than air and does not support combustion. Answer. Class B and C . (5) Answer. Also write the false statements in their correct form. Also explore over 15 similar quizzes in this category. (ii) The cutting down of trees to obtain as a wood fuel leads to deforestation which is very harmful to the environment. The lowest temperature at which a substance catches fire is called its …………. They can also be used on small class B (liquid) fires, but cooling effects on the liquid are limited and the fire may re-ignite after it has been extinguished. TRUE/FALSE. a. Please enable Cookies and reload the page. Class A materials may also smolder and re-ignite. 23. b. Twenty to thirty seconds. PASS c. PALS d. None of the Above True or False: 4. b. The other one is called a propellant and is a pressurized chemical that makes the fire-fighting substance come out when you press the extinguisher handle. For fires involving electrical equipment and inflammable materials like petrol, then carbon dioxide (C02)is the best extinguisher. Carbon Dioxide (CO 2) extinguishers: The extinguishing media is pressurized CO 2. Question. Maintain a safe escape route in case the fire gets out of control. Fuel. 12. Name one unit in which the heat liberated by a fuel is measured. (e) The substances which have very low……………… temperature and can easily catch fire with a flame are called…………….. substances. (a) kilojoule per litre (b) kilogram per millilitre Most fire extinguishers have enough agent to last at least 5 minutes. (a) magnesium oxide, water and light (b) magnesium oxide and heat So, in the incomplete supply of oxygen, coal burns to produce carbon monoxide which is highly poisonous gas. The watch glass containing petrol will catch fire instantly because its ignition temperature is very low. (c) Alcohol, CNG and LPG are inflammable substances. (a) Air is necessary for combustion. These are as follows: Such a reaction is called explosion. Fire Extinguisher Quiz Thursday, March 08, 2001 1) True or False Carbon Dioxide ( CO 2) extinguishers can be used for all fires. 3. (ii) Magnesium is a non-combustible metal. 30 What do you understand by fuel efficiency? These can be fires where cooking liquids, oil, gasoline, kerosene, or paint have become ignited. After noticing a fire, when should you raise an alarm? (e) Greater the calorific value, better is the fuel. (a) Air is necessary for combustion. (a)—(iv), (b)-(vi), (c)-(v), (d)—(iii), (e)-(i), (f)-(ii), Question. b. Be thorough when using a CO 2 extinguisher. Match the items of Column A with the items of Column B. How do fire extinguishers work? Carbon Dioxide extinguishers are filled with non-flammable carbon dioxide gas under extreme pressure. Throughout the forest cleanest fuel as the cleanest fuel air around the fire like a blanket for combustibles... 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