8-Science-Combustion and Flame Worksheet
8-Science-Combustion and Flame Worksheet
8-Science-Combustion and Flame Worksheet
CHEMISTRY-VIII CLASS
30
Combustion and Flame-Worksheet
temperature and can easily catch fire with a flame are called
substances.
(e) The substances which vapourise during , give flame.
17. Two glass jars A and B are filled with carbon dioxide and
oxygen gases, respectively. In each jar a lighted candle is
placed simultaneously. In which jar will the candle remain
lighted for a longer time and why?
25. Fill in the blanks using the words given in the box.
30. You are provided with three watch glasses containing milk,
petrol and mustard oil, respectively. Suppose you bring a
burning candle near these materials one by one, which
material(s) will catch fire instantly and why?
31. Manu was heating oil to fry potato chips. The cooking oil all of
a sudden caught fire; he poured water to extinguish the fire.
Do you think this action was suitable. If yes, why? If not, why
not? In such a condition what should Manu have done?
33. Give two examples each for a solid, liquid and gaseous fuel
alongwith some important uses.
34. The calorific values of petrol and CNG are 45000 kJ/kg and
50,000 kJ/kg, respectively. If you have vehicle which can run
on petrol as well as CNG, which fuel will you prefer and why?
36. Forest fire produces a lot of air pollution. Write in brief about
the reasons of forest fires.
37. Complete the crossword Fig. 6.1 with the help of the clues :
Across Down
1. Non-metal which catches 2. A chemical process in
which fire if exposed to air (10) a substance reacts
with
oxygen to give off heat. (10)
3. The lowest temperature at 4. Petrol is used as a
which a substance catches in automobiles. (4)
fire is called its
temperature. (8)
5. The most common fire 6. It is as hard as stone and
extinguisher. (5) black in colour. (4)