NCERT Class VIII Science Solutions: Chapter 6-Combustion and Flame Part 5

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Question 11:

In an experiment of a fuel was completely burnt. The heat produced was measured to be Calculate the calorific value of the fuel.


Question 12:

Can the process of rusting be called combustion? Discuss.


No, as rusting is a very slow process as compared to combustion and the heat evolve in combustion is much more than rusting. Rusting can take place at room temperature but combustion need an ignition temperature.

Question 13:

Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. Abida kept the beaker near the wick in the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose water will get heated in a shorter time?


The outermost part of the flame is the hottest one, so Rakesh’s water will get heated in a shorter time.

Result for water heated in candle

Water Heated in Candle

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