NCERT Class VIII Science Solutions: Chapter 6-Combustion and Flame Part 7 (For CBSE, ICSE, IAS, NET, NRA 2023)
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Question 37:
Forest fire produces a lot of air pollution. Write in brief about the reasons of forest fires.
Answer:
- At high temperature, sometimes dry grass catches fire which spreads throughout the forest.
- Camp fire may also be a reason.
- Human negligence.
- Lightening.
Question 38:
Complete the crossword Fig with the help of the clues:
Across:
1. Non-metal which catches fire if exposed to air (10)
3. The lowest temperature at which a substance catches fire is called its ________ temperature. (8)
5. The most common fire extinguisher. (5)
Down:
2. A chemical process in which a substance reacts with oxygen to give off heat. (10)
4. Petrol is used as a ________ in automobiles. (4)
6. It is as hard as stone and black in colour. (4)
Answer:
1. Non-metal which catches fire if exposed to air - Phosphorus
3. The lowest temperature at which a substance catches fire is called its ________ temperature - Ignition
5. The most common fire extinguisher - water
Down:
2. A chemical process in which a substance reacts with oxygen to give off heat - Combustion
4. Petrol is used as a ________ in automobiles - Fuel
6. It is as hard as stone and black in colour - Coal