8th Class Science Combustion and Flame Question Bank

done Combustion and Flame HOTS Objective Problems Total Questions - 20

• question_answer1)
  Three candles X, Y, and Z are fixed on a table. A glass chimney is placed over candle X, and is rested on wooden blocks in a manner which allows the entrance of oxygen. To candle Y, a glass chimney is placed in such a way that it is simply rested on the table. For candle Z, a similar arrangement is made along with the placement of a glass plate over the chimney. Candle _____i____ bums freely. The flame of candle _____ii_____ will flicker off giving smoke, and that of candle _____iii_____  will simply go off. The information in which alternative completes the given statements?
  A)
    i-X, ii-Y, iii-Z                       done clear
  B)
   i-Z, ii-Y, iii-X done clear
  C)
    i-Y, ii-X, iii-Z                       done clear
  D)
   i-Z, ii-X, iii-Y done clear
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• question_answer2)
  Which of the following tables correctly represents the substance with the type of combustion?
  A)

  Substance	Type of combustion
  LPG	Rapid
  Phosphorus	Spontaneous
  Dynamite	Explosion

  done clear
  B)

  Substance	Type of combustion
  LPG	Spontaneous
  Glass	Explosion
  Dynamite	Rapid

  done clear
  C)

  Substance	Type of combustion
  Phosphorus	Explosion
  LPG	Rapid
  Dynamite	Spontaneous

  done clear
  D)

  Substance	Type of combustion
  LPG	Spontaneous
  Glass	Rapid
  Dynamite	Explosion

  done clear
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• question_answer3)
  The ignition temperature of sodium is very _____i____. To prevent its _____ii_______ combustion, it is stored under _______iii______,. The information in which alternative completes the given statements?
  A)
   i-low, ii-rapid, iii-Kerosene done clear
  B)
   i-low, ii-spontaneous, iii-Kerosene done clear
  C)
   i-high, ii-rapid, iii- water done clear
  D)
   i-high, ii-spantaneous, iii-water done clear
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• question_answer4)
  The gas that is used in fire extinguishers is
  A)
   Nitrogen                             done clear
  B)
   Hydrogen done clear
  C)
   Sulphur dioxide               done clear
  D)
   Carbon dioxide done clear
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• question_answer5)
  Radhika took some sodium bicarbonate in a conical flask and set up the apparatus as shown in the given diagram. She added cone. sulphuric acid into the conical flask using a funnel. Which of the flowing statements is correct for the given experiment?
  A)
    The gas coming out of the delivery tube is heavier than air and will make the candle glow brightly. done clear
  B)
   The gas coming out of the delivery tube is lighter than air and will extinguish the candle. done clear
  C)
   The gas coming out of the delivery tube is heavier than air and will extinguish the candle. done clear
  D)
    The gas coming out of the delivery tube is lighter than air and will make the candle glow brightly. done clear
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• question_answer6)
  Which of the following tables correctly matches the given zones of a candle flame with their respective characteristics?
  A)
   

  	Zone	Characteristic
  i	Innermost	Least hot and black
  ii	Luminous	Moderately hot and yellow

  done clear
  B)

  	Zone	Characteristic
  i	Outermost	Hottest and black
  ii	Luminous	Least hot and blue

  done clear
  C)

  	Zone	Characteristic
  i	Non-luminous	Least hot and blue
  ii	Innermost	Hottest and black

  done clear
  D)

  	Zone	Characteristic
  i	Non-luminous	Moderately hot and yellow
  ii	Outermost	Least hot and black

  done clear
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• question_answer7)
  Ordinarily, kerosene oil bums in air with a yellow flame. However, in stoves, it bums with a blue flame. Which of the following statements explains the above observation?
  A)
   Complete combustion of kerosene takes place in stoves. done clear
  B)
   The ignition temperature of kerosene is attained easily in stoves. done clear
  C)
   Stoves are made of iron and kerosene bums with a blue flame in the presence of iron. done clear
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• question_answer8)
  Consider the given diagram X and Y in the given figure represent
  A)
   Sulphur oxides and nitrogen oxides done clear
  B)
   Silicon oxides and nitrogen oxides done clear
  C)
   Sulphur oxides and chlorine gas done clear
  D)
   Silicon oxides and chlorine gas done clear
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• question_answer9)
  Incomplete combustion of fossil fuels releases a gas 'X?. This gas is poisonous in nature and it bums with a blue flame. Which gas does X represent?
  A)
   Ozone                  done clear
  B)
   Chlorine done clear
  C)
   Carbon dioxide                done clear
  D)
   Carbon monoxide done clear
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• question_answer10)
  Harish    performed    two    different experiments I and II. In experiment I, he provides a substance 'X? with some heat. He found out that a sudden reaction takes place to form heat, light, and sound. In experiment II, he provides heat to a substance 'Y?. He found out that when Y bums, only heat and light are produced. Experiment I represents   an   example of __i__, and experiment II represents an example of __ii___. The information in which alternative completes the given statement?
  A)
   i-Explosion, ii-Rapid combustion done clear
  B)
   i-Explosion, ii-Sportaneous combustion done clear
  C)
   i-Spontaneous combustion, ii-Explosion done clear
  D)
   i-Rapid combustion, ii-Spontaneous combustion done clear
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• question_answer11)
  Sakshi took a piece of four substances W, X, Y, and Z. She tried to bum each of them by bringing a lighted matchstick near them. She observed that Y and Z bum readily, whereas W bums readily only after sustained heating. However, X does not bum at all. Among the given substances taken by Sakshi, which substance has the highest ignition temperature?
  A)
   W                           done clear
  B)
   X      done clear
  C)
   Y                             done clear
  D)
   Z done clear
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• question_answer12)
  Swati took two glass plates I and II. She introduced them to the-different zones of a flame (as shown in the figure). She held them there with a pair of tongs for about 10 seconds. She observes that a circular-blackish ring has developed on plate I, while no such blackish ring is observed on plate II. From Swati's experiment, it can be concluded that ______i______ zone is the zone containing unburnt particles, and the ___ii___ zone is the zone of complete combustion. The information in which alternative completes the given statement?
  A)
   i-outermost, ii-Innermost done clear
  B)
   i-Innermost, ii-Outermost done clear
  C)
   i-Innermost, ii-Middle. done clear
  D)
   i-Middle, ii-Innermost done clear
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• question_answer13)
  Rajesh made two paper cups I and II by folding a sheet of paper. He pours 50 mL water in cup II, and heats both cups separately with the help of a candle (as shown in the figure). Rajesh observes that while one paper cup burns readily, the other does not burn. He observed that paper cup ____i____ does not burn since its ignition temperature was ______ii______ while heating. The information in which alternative completes the given statement?
  A)
   i-I, ii-reached   done clear
  B)
   i-II, ii-reached done clear
  C)
   i-I, ii-not reached      done clear
  D)
   i-I, ii-not reached done clear
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• question_answer14)
  Geeta took four combustible substances I, II, II, and IV. She found out that the ignition temperatures of I, n, III, and IV is\[{{233}^{o}}C\], \[{{473}^{o}}C,\] \[{{210}^{o}}C,\]and \[{{170}^{o}}C,\] respectively. She heats all the substances to \[{{190}^{o}}C,\]. Among the given substances, which substance will catch fire when heat is supplied to it?
  A)
   I                                              done clear
  B)
   II done clear
  C)
   III                                           done clear
  D)
   IV done clear
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• question_answer15)
  If a goldsmith wants to make jewellery of gold and silver, then he has to melt them. To do this, he will use the ___i____ zone of the flame as this zone is the ____ii____ zone of the flame. The information in which alternative completes the given statement?
  A)
   i-Innermost, ii-Hottest done clear
  B)
   i-Innermost, ii-Moderately hot done clear
  C)
   i-Outermost, ii-Moderately hot done clear
  D)
   i-Outermost, ii-Hottest done clear
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• question_answer16)
  A certain gas is used by living organisms for respiration, and this is used in the process of combustion. In the process of combustion, the gas reacts with combustible substances to produce heat. The mentioned gas is
  A)
   Oxygen                               done clear
  B)
   Nitrogen done clear
  C)
   Carbon dioxide                done clear
  D)
   Carbon monoxide done clear
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• question_answer17)
  Sujit was performing an experiment in the laboratory. He collected four substances I, II, III, and IV and kept all of them in contact with air at room temperature. He observed that substance III suddenly bursts into flames. Then, he heated I, II, and IV and found out that while I and II catch fire, substance IV does not. However, substance IV catches fire on prolonged heating. Which substance undergoes spontaneous combustion in Sujit's experiment?
  A)
   I                                              done clear
  B)
   II done clear
  C)
   III                           done clear
  D)
   IV done clear
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• question_answer18)
  Ravi takes three substances X, Y, and Z. On heating these substances he observes that they bum at different temperatures. He finds out that X catches fire on little heating, while Y and Z do not catch fire. On further heating of Y and Z, he observes that Y catches fire, while Z does not. The correct arrangement of X, Y, and Z in order of their increasing ignition temperatures is
  A)
   \[X<Y<Z\]           done clear
  B)
   \[Z<Y<X\] done clear
  C)
   \[Z<X<Y\]                           done clear
  D)
   \[Y<X<Z\] done clear
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• question_answer19)
  Why is it never advised to sleep in a room with burning coal fire?
  A)
   Incomplete combustion of coal produces carbon monoxide, which is poisonous                      done clear
  B)
   Incomplete combustion of coal produces carbon dioxide, which is poisonous done clear
  C)
   Burning of coal produces oxides of nitrogen, the fumes of which are very toxic done clear
  D)
   Burning of coal produces oxides of nitrogen that combine with moisture present in air to form acids done clear
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• question_answer20)
  Global warming is a result of ____i_____ percentage of ____ii_____ in air. The information in which alternative completes the given statement?
  A)
   i-An increased, ii-Carbon dioxide done clear
  B)
   i-A decreased, ii-Carbon dioxide done clear
  C)
   i-An increased, ii-nitrogen done clear
  D)
   i-A decreased, ii-nitrogen done clear
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