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NCERT Class VIII Science Solutions: Chapter 6 - Combustion and Flame Part 4
SHORT ANSWER QUESTIONS
Question 21:
Boojho wants to separate the following materials as combustible and non-combustible. Can you help him?
Charcoal, chalk, stone, iron rod, copper coin, straw, cardboard, glass, paper, candle, wood.
Answer:
- Combustible - charcoal, straw, card board, paper, candle wood,
- Non-combustible - chalk, stone, iron rod, copper coin, glass.
Question 22:
Indicate whether the following statements are true or false. Also write the false statements in their correct form.
- Air is necessary for combustion.
- Magnesium is a non-combustible metal.
- Carbon dioxide is an excellent fire extinguisher.
- Calorific value of wood is higher than that of coal.
Answer:
- Air is necessary for combustion. (True)
- Magnesium is a non-combustible metal. (False)
Hint: Magnesium is a combustible metal
- Carbon dioxide is an excellent fire extinguisher. (True)
- Calorific value of wood is higher than that of coal. (False)
Hint: Calorific value of coal is higher than that of wood.
Question 23:
Match the items of Column A with the items of Column B.
Column A | Column B |
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Answer:
Column A | Column B |
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Oxides of sulphur and nitrogen | iv Acid rain |
CNG | vi Fuel for automobiles. |
Oxygen | v Necessary for combustion |
Inflammable substance | iii Very low ignition temperature |
Carbon dioxide | i Fire extinguisher |
Carbon monoxide | ii Incomplete combustion of coal |
Question 24:
Match the following for the flame of a candle.
Column A | Column B (zone) | Column C (colour) |
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Answer:
Column A | Column B (zone) | Column C (colour) |
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| iii Outer zone of complete combustion | a Blue |
| ii Middle zone of partial combustion | c Yellow |
| i Innermost zone of unburnt wax vapours | b Black |