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  5. Combustion and Flame

8th Class Science Combustion and Flame Question Bank Combustion and Flame HOTS Objective Problems

  • question_answer
    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                      

    B)  i-Z, ii-Y, iii-X

    C)   i-Y, ii-X, iii-Z                      

    D)  i-Z, ii-X, iii-Y

    Correct Answer: A

    Solution :

      Candle\[X\]burns freely as air can enter the chimney from below. However, the chimney is placed over candle Y in such a way that it is rested on the table. This means that air does not enter the chimney from below. Thus, the flame of candle Y flickers and produces smoke. On the other hard, the flame of candle Z goes off as air is not available for burning. The correct answer is A.


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