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Why is a match stick rubbed against a rough surface to light it ?
On rubbing the match stick in the rough surface, the friction converts this work into heat. The heat raises the temperature of the chemical present on the match stick head to its ignition temperature. Due to this the chemical substance catches fire and the match stick starts burning.
Give reasons :
Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.
Make a labelled diagram of candle flame.
Name the unit in which the calorific value of a fuel is expressed.
Explain how CO2 is able to control fires.
It is difficult to burn a heap of green leaves but dry leaves catch fire easily. Explain.
Which zone of a flame does a goldsmith use for melting gold and silver and why ?
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.
Can the process of rusting be called combustion ? Discuss.
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 of the flame. Whose water will get heated in a shorter time?
What are fuels ?
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