8th Class Science Combustion and Flame Question Bank

done Combustion and Flame Total Questions - 35

• question_answer1)
  What are the two main hydrocarbons present in L.P.G.?
  A)
   Butane + propane done clear
  B)
                          Butane + isobutene done clear
  C)
                          Propane + ethane done clear
  D)
                          Methane + ethane done clear
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• question_answer2)
  What is the heat produced by burning 1 g of fuel completely known as?
  A)
   Heat capacity done clear
  B)
                          Calorific value done clear
  C)
                          Vapour density done clear
  D)
                          Boiling point done clear
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• question_answer3)
  Which of the following has the highest calorific value?
  A)
   Petrol                                   done clear
  B)
                          Coke     done clear
  C)
                          Natural gas                        done clear
  D)
                          Kerosene                           done clear
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• question_answer4)
  Which of the following has the characteristics of a good fuel?
  A)
   Coke                                     done clear
  B)
                          Butane                done clear
  C)
                          Coal                                      done clear
  D)
                          Kerosene                           done clear
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• question_answer5)
  What is burning of a substance in the presence of air with the evolution of heat called?
  A)
   Distillation          done clear
  B)
                          Carbonization                   done clear
  C)
                          Combustion                      done clear
  D)
                          Refining done clear
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• question_answer6)
  When methane burns in air, what are the products formed?
  A)
  \[C{{O}_{2}}+2{{H}_{2}}O+heat\] done clear
  B)
                         \[C{{O}_{2}}+{{H}_{2}}\] done clear
  C)
                         \[CO+{{O}_{2}}\] done clear
  D)
                          \[C{{O}_{2}}+{{O}_{2}}+heat\] done clear
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• question_answer7)
  What kind of reaction is combustion?
  A)
   Reduction                          done clear
  B)
                          Redox                  done clear
  C)
                          Substitution                      done clear
  D)
                          Oxidation done clear
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• question_answer8)
  Which of the following is a non- combustible substance?
  A)
   Coke                                     done clear
  B)
                          Diamond                             done clear
  C)
                          Coal                                      done clear
  D)
                          Wood done clear
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• question_answer9)
  What is the lowest temperature at which a substance starts burning called?
  A)
   Minimum temperature done clear
  B)
                          Maximum temperature done clear
  C)
                          Boiling temperature done clear
  D)
                          Ignition temperature done clear
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• question_answer10)
  If the temperature falls below its ignition temperature, then what happens to the burning substance?
  A)
   It gets extinguished. done clear
  B)
                          It burns brightly. done clear
  C)
                          It burns dimly. done clear
  D)
                          It burns with smoke. done clear
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• question_answer11)
  Which of the following is an example of rapid combustion?
  A)
   Candle done clear
  B)
                          Cracker done clear
  C)
                          White phosphorus done clear
  D)
                          Sulphur done clear
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• question_answer12)
  In which of the following types of combustion are heat, light and sound produced?
  A)
   Rapid                                    done clear
  B)
                          Explosive                            done clear
  C)
                          Spontaneous    done clear
  D)
                          All of the above done clear
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• question_answer13)
  I Match the entries in Column-l with those in Column-ll correctly.

  	Column - I		Column - II
  (a)	Dark inner zone	(i)	Hottest part (No carbon)
  (b)	Blue zone	(ii)	Partial combustion
  (c)	Luminous zone	(iii)	Unburnt vapours of wax
  (d)	Non-luminous zone	(iv)	Complete combustion

  A)
   a-1, b-2, c-3, d-4 done clear
  B)
                          a-2, b-3, c-4, d-1 done clear
  C)
                          a-3, b-4, c-2, d-1 done clear
  D)
                          a-4, b-1, c-2, d-3 done clear
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• question_answer14)
  What does the blue zone in an L.P.G. flame indicate?
  A)
   Unburnt vapours done clear
  B)
                          Partial decomposition done clear
  C)
                          Moderately hot done clear
  D)
                          Hottest zone of complete combustion done clear
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• question_answer15)
  What does natural gas contain?
  A)
   Methane, ethane, propane. done clear
  B)
                          Butane, propane and ethane. done clear
  C)
                          Pentene, methane and ethylene. done clear
  D)
                          Hexane, butane and ethane. done clear
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• question_answer16)
  How is synthetic petrol produced?
  A)
   From petroleum              done clear
  B)
                          From wood                        done clear
  C)
                          From coal           done clear
  D)
                          From L.P.G. done clear
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• question_answer17)
  Arrange the following fuels in the increasing order of their calorific value.

  (i) Petrol

  (ii) Wood

  (ii) Coal

  (iv) Natural gas

  A)
   (i), (ii), (iii), (iv) done clear
  B)
                          (ii), (iii), (iv) and (i) done clear
  C)
                          (ii), (i), (iii) and (iv) done clear
  D)
                                          (ii), (iii), (i) and (iv)                 done clear
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• question_answer18)
  What does the incomplete combustion of a fuel give?
  A)
   CO                                         done clear
  B)
                         \[C{{O}_{2}}\]                                    done clear
  C)
                          \[S{{O}_{2}}\]                                   done clear
  D)
                          Oxides of nitrogen done clear
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• question_answer19)
  The total amount of heat produced by a fuel having a calorific value of 20 kJ kg 1 was found to be 50,000 joules. How much fuel was burnt?
  A)
   2500 kg                                done clear
  B)
                          250 kg                  done clear
  C)
                          25 kg                                     done clear
  D)
                          2.5 kg done clear
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• question_answer20)
  What is combustion?
  A)
   An exothermic reaction done clear
  B)
                          An endothermic reaction done clear
  C)
                          A displacement reaction done clear
  D)
                          A reduction reaction done clear
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• question_answer21)
  Inspite of the danger involved with hydrogen, it is used for some applications. Where is it used?
  A)
   Rocket fuel done clear
  B)
                          Oxyhydrogen flame done clear
  C)
                          Car fuel done clear
  D)
                          All of the above done clear
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• question_answer22)
  A family consumes 12 kg of L.P.G. in 30 days. Calculate the average energy consumed per day, if the calorific value of L.P.G. is 50 kJ kg1.
  A)
   10,000 J per day done clear
  B)
                          15,000 J per day done clear
  C)
                                          20,000 J per day                 done clear
  D)
                                          25,000 J per day done clear
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• question_answer23)
  What ignition temperature does an inflammable substance have?
  A)
                   More than 100°C                 done clear
  B)
                                          Less than 100°C                 done clear
  C)
                                          More than 200 °C                 done clear
  D)
                                          Between 200 °C to 350 °C done clear
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• question_answer24)
  What is the disadvantage of incomplete combustion of a fuel?
  A)
                           Unburnt carbon gets released.                 done clear
  B)
                                          Air gets polluted.                 done clear
  C)
                                          Respiratory problems arise.                 done clear
  D)
                                          All of the above                 done clear
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• question_answer25)
  Which of the following is the best extinguisher for inflammable materials?
  A)
                           Water                 done clear
  B)
                                          Sulphur dioxide                 done clear
  C)
                                          Carbon dioxide                 done clear
  D)
                                          Carbon monoxide done clear
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• question_answer26)
  On which of these factors does the flame produced by a fuel depend upon?
  A)
                   Calorific value                 done clear
  B)
                                          Amount of oxygen                 done clear
  C)
                                          The chemical composition of a fuel                 done clear
  D)
                                          All of the above done clear
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• question_answer27)
  Which of the following statements is NOT true?
  A)
                   \[C{{O}_{2}}\]is the best fire extinguisher.                 done clear
  B)
                                          Global warming can cause acid rain.                 done clear
  C)
                          Burning of coal and diesel releases sulphur dioxide gas. done clear
  D)
                                          L.P.G. has higher calorific value than biogas. done clear
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• question_answer28)
  Why is L.P.G, used as domestic fuel, mixed with a strong smelling volatile liquid like mercaptan?
  A)
                   For better combustion                 done clear
  B)
                                          For good smell/fragrance                 done clear
  C)
                                          For detection of gas leakage                 done clear
  D)
                                          For higher calorific value done clear
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• question_answer29)
  Hydrogen gas has the highest calorific value i.e., \[150\,kJ\,k{{g}^{-1}},\]yet it is not used as a fuel. Why?
  A)
                   It is explosive in nature.                 done clear
  B)
                                          It causes storage problem.                 done clear
  C)
                                          It causes transportation problem.                 done clear
  D)
                                          All of the above                 done clear
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• question_answer30)
  When wood is used as a fuel in chullahs, gaps are left in between logs of wood. Why is it done so?
  A)
                   To facilitate movement of air                 done clear
  B)
                                          To prevent more consumption of wood                 done clear
  C)
                          To control temperature done clear
  D)
                                          All of these done clear
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• question_answer31)
  For a spontaneous combustion to take place, which condition given below is necessary?                
  A)
                   Flame                 done clear
  B)
                                          Low ignition temperature                 done clear
  C)
                                          Rise in temperature                 done clear
  D)
                                          Temperature below 30°C done clear
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• question_answer32)
  An electric spark is struck between two electrodes placed near each other, inside a closed tank full of petrol. What will happen?
  A)
                   Spontaneous combustion of petrol                 done clear
  B)
                                          Explosion                 done clear
  C)
                                          Slow combustion of petrol                 done clear
  D)
                          Nothing will happen done clear
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• question_answer33)
  One gram of which of these will give out the maximum amount of heat by complete combustion?
  A)
   Wood                                   done clear
  B)
                                          Coal                      done clear
  C)
                                          Diesel                                   done clear
  D)
                          Biogas done clear
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• question_answer34)
   What are the essential requirements for a fire to start and continue?

  (i) Fuel

  (ii) Air (oxygen)

  (iii) Heat

                 
  A)
                   Only (i) and (ii)                 done clear
  B)
                                          Only (ii) and (iii)                 done clear
  C)
                                          Only (i) and (iii)                 done clear
  D)
                                          (i), (ii) and (iii)                 done clear
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• question_answer35)
  Which of the following statements is NOT true?
  A)
   Spontaneous combustion takes place without any apparent cause. done clear
  B)
                                          The luminous zone of a flame has high temperature. done clear
  C)
                          Carbon dioxide gas causes global warming. done clear
  D)
                          The calorific value of a fuel is expressed in \[kJ/k{{g}^{-1}}.\] done clear
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