Q.1. Define Combustion and ignition temperature. List conditions under which combustion can take place. Q.2. What is caused by burning of wood and coal? Q.3. What type of fire extinguishers should be used to control the fire produced by oil? Q.4. Explain how the use of CNG in automobiles has reduced pollution in our cities. Q. 5. Compare LPG and wood as fuels. Q.6. Give reasons. (a) Water is not used to control fires involving electrical equipment. (b) LPG is a better domestic fuel than wood. (c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not. Q.7.Make a labelled diagram of a candle flame and write a few lines on the same. Q.8. Name the unit in which the calorific value of a fuel is expressed. Q.9. Explain how CO2 is able to control fires. Q.10. It is difficult to burn a heap of green leaves but dry leaves catch fire easily. Explain. Q.11.Which zone of a flame does a goldsmith use for melting gold and silver and why? Q.12. Can the process of rusting be called combustion? Discuss. + 53 Multiple Choice Questions with Answers

Q.1. Define Combustion and ignition temperature. List conditions under which combustion can take place. Q.2. (a) What is caused by burning of wood and coal? Q.2(b) Liquid fuel used at homes is called ? Q.2(c) Fuel starts burning when it is heated up to its _____ temperature? Q.2 (d) What type of fire extinguishers should be used to control the fire produced by oil? Q.3. Explain how the use of CNG in automobiles has reduced pollution in our cities. Q. 4. Compare LPG and wood as fuels.

Q. 5. Give reasons. (a) Water is not used to control fires involving electrical equipment. (b) LPG is a better domestic fuel than wood. (c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not. Q.6. Make a labelled diagram of a candle flame Q.7. Name the unit in which the calorific value of a fuel is expressed. Q.8. Explain how CO2 is able to control fires. Q.9. Why it is difficult to burn a heap of green leaves but dry leaves catch fire easily? Q.10. Which zone of a flame does a goldsmith use for melting gold and silver and why? Q.11. In an experiment 4.5 kg of a fuel was completely burnt. The heat produced was measured to be 180,000 kJ. Calculate the calorific value of the fuel. Q.12. Can the process of rusting be called combustion? Discuss. Q.13. In which zone of the candle flame, water gets heated in a shorter time?

Q. 1.Which one of the following gases is used in combustion? (a) Hydrogen(b) Oxygen(c) Nitrogen(d) Carbon dioxide Q.2. Which of the following is not a fossil fuel? (a) Coal (b) Petroleum (c) Natural gas (d) Water gas Q.3. Substances which catch fire are called (a) acids (b) bases (c) combustible (d) burners Q.4.. The SI unit of the calorific value of a fuel is :- A. N/kg B. kJ/kg C. KW/kg D. J/kg Q.5. The color of outer zone of candle flame is :- A. orange B. blue C. red D. yellow Q.6. Water cannot be used as a fire extinguisher to put out – A. Burning charcoal B. Burning cloth C. Burning oil D. Burning wood Q.7. Which of the following factors are essential to ignite a fire? A. Heat B. Fuel C. Air (oxygen) D. All of these Q.8. Which fuels are used for running automobiles? a. Wood b. Coal c. Diesel d. Charcoal Q.9. Fuel may be- a. Solid b. Liquid c. Gas d. All of these Q.10.The lowest temperature at which a substance catches fire is called its- a) Boiling point b. Melting point c. Ignition temperature d. Critical temperature Q.11. Which one of the following is non combustible? a. Stone piece b. Paper c. Straw d. Matchsticks Q.12. Fire extinguisher- a. Cut off the supply of air b. Bring down the temperature of fuel c. Both (a) & (b) d. None of these Q.13. Rapid combustion is a. When gas burns, it produces heat and light b. When material suddenly burst into flames c. When there is evolution of heat d. None of these Q.14. Acid rain contains mainly (a) oxygen and nitrogen gas (b) fluorine and chlorine gas (c) magnesium oxide (d) nitrogen oxide and sulphur dioxide Q.15.Which zone represents the partial combustion in candle flame? (a) Outer zone (b) Middle zone (c) Inner zone (d) Lower zone Q.16. Burning coal in a closed room will produce (a) nitrogen oxides (b) carbon dioxide (c) carbon monoxide (d) oxygen Q.17 . Which is non-combustible substance? (a) Wood (b) Paper (c) Iron nails (d) Straw Q.18.Out of these, which is able to control fires? (a) NH3 (b) H2 (c) CO2 (d) F2

Q.19. An ideal fuel is cheap, readily available, easily combustible and easy to transport. It has high calorific value. It does not produce gases or residues that pollute the environment. Based on the above statements which of the following is closest to being an ideal fuel? A. Compressed Natural Gas (CNG) B. Kerosene C. Petrol D. Coal Q.20. When a cracker is ignited, a sudden reaction takes place with the evolution of heat, light and sound. Identify the type of combustion? A. Random combustion B. Rapid combustion C. Spontaneous combustion D. Explosion Q.21. The efficiency of a fuel is expressed in terms of its - A. density B. calorific value C. volume D. purity Q.22. The suspended particles released by combustion of coal in air may lead to a health disease. Select the correct option. A. Goitre B. Arthritis C. Asthma D. Bone cancer Q. 23. Innermost zone of the candle flame is the a. Hottest part b. Moderately hot part c. Least hot part d. Cold part Q.24. Which is better domestic fuel : a. CNG b. LPG c. Wood d. Coal Q.25. The substances which have very low ignition temperature will a. Catch fire easily b. Will not catch fire c. Catch fire after some time d. None of these Q.26. Combustion is a- a. Physical process b. Chemical process c. Both (a) & (b) d. None of these Q.27. Like fuel the sun also provides heat and light. The process taking place in the sun is called a. Combustion b. Nuclear process c. Burning d. All of these Q.28. CO2 extinguishers help extinguish fires by – A. Cutting supply of nitrogen. B. Limiting the supply of fuel. C. Reducing the heat of the surroundings. D. Cutting the supply of oxygen Q.29. Which of the following cannot be used to extinguish the fire caused by electricity? A. Carbon dioxide B. Blanket C. Sand D. Water Q.30. Charcoal burns in air producing- a. CO2 b. CO c. H2 d.O2 Q.31. Which of the following is inflammable substance? a. Petrol b. Wood c. Paper d. Straw Q.32 . Good fuel is a. Readily available b. Cheap c. Burn easily in air d. All of these Q.33. Unburnt carbon particles causes a. Stomach infection b. Respiratory problems c. Brain infections d. Throat problems 34. Incomplete combustion gives a. CO2 b. CO c. Carbon d. None of these Q. 35. Which of the following is/are carbon fuel a. Wood b. Coal c. Petroleum d. All of these Q.36. Acid rain is caused by oxides of a.Sulphur, Nitrogen b. Sulphur, Carbon c. Carbon, Nitrogen d. Phosphorous, Carbon Q.37. The head of the safety match contains a. Antimony trisulphide b. Potassium Chlorate c. Both (a) and (b) d. None of these Q.38.Combustion of most fuels releases a. CO2 b. SO2 c. NO2 d. Oxygen Q.39.Burning of coal and diesel releases a. NO2 b. CO2 c. SO2 d. CO Q.40. The burning of LPG is an example of (a) rapid combustion (b) spontaneous combustion (c) slow combustion (d) explosion Q.41.The products of combustion are a. Carbon dioxide and water b. Oxygen and water c. Only carbon dioxide d. Only oxygen Q.42. The most common fire extinguisher is a. Water b. CO2 c. Oxygen d. Hydrogen Q.43. Petrol engine gives off gaseous oxides of a. Sulphur b. Nitrogen c. Phosphorous d. Carbon Q.44.Unburnt carbon particles causes a.Stomach infections b.Respiratory problems c.Brain infections d. Throat problems Q.45. A temperature at which the substance burns is called (a) melting (b) boiling temperature (c) kindling temperature (d) evaporation Q.46. When the match struck against rubbing surface, red phosphorous a. Converts into white phosphorous b. Reacts with potassium chlorate c. Ignite antimony trisulphide d. None of these Q. 47. Best extinguisher for inflammable Materials is a. Water b. SO2 c. CO2 d. CO Q.48. CO2 is stored as a liquid in cylinder at a. High pressure b. Low pressure c. High temperature d. Low temperature Q. 49. Water is not suitable for fire involving a. Oil b. Petrol c. Both (a) & (b) d. None of these Q.50. Substance which vaporize during burning gives a. Sound b. Flame c. Combustion d. None of these Q. 51.Which is a solid fuel? a. Petrol b. Diesel c. Wax d. Wood Q.52. Ideal fuel has ____ calorific value a. Low b. High c. Moderate d. Zero Q.53.Amount of heat energy produced on _____combustion of 1kg of fuel is Calorific value a. Incomplete b. Complete c. Half d. None of these 53(b).Global warming is caused due to____ concentration of CO2 in air a. Decreased b. Increased c. Both (a) & (b) d. None of these