COMBUSTION AND FLAME
IMPORTANT QUESTIONS
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| combustion and flame |
Fill in the blanks:
1. The substance which has a very low ignition temperature and can easily catch fire are called ----------.
2. The calorific value of a fuel is expressed as -----------.
3. ---------- is the only non-metal which catch fire if exposed to air.
4. The fire produced by oil and petrol cannot be extinguished by --------.
5. The burning of fuels like wood and cow dung cake releases unburnt ------- particles in the air.
MCQ
6. Light and heat are produced in the Sun by:
a. burning wood
b. oxygen
c. nuclear reaction
d. boiling water
7. The lowest temperature at which a substance catches fire is known as:
a. burning temperature
b. flaming temperature
c. lowest temperature
d. ignition temperature
8. Which among these are required for the production of a fire?
a. fuel, water, heat
b. fuel, oxygen, heat
c. heat, burner, water
d. heat, water, oxygen
9. During the explosion, there is an evolution of:
a. light
b. heat
c. sound
d. all of these
10. When we heat a paper cup containing water, it does not catch fire because:
a. paper is inflammable
b. water makes it wet
c. ignition temperature of paper is not reached due to the presence of water
d. none of these
ASSERTION-REASON QUESTIONS
In the following questions, a statement of assertion(A) and a statement of the reason(R) are given. Select the correct option for the following assertion-reason questions:
a. Both A and R are true and R is the correct explanation of A.
b. Both A and R are true and R is not the correct explanation of A.
c. A is true but R is false.
d. A is false and R is true.
e. Both A and R are false.
11. Assertion(A)-Kerosene oil catches fire easily.
Reason(R)-The ignition temperature of kerosene is very high.
12. Assertion(A)- Goldsmiths usually blow at the inner zone of a flame for melting gold.
Reason(R)- The innermost zone of a flame is the hottest part.
13. Assertion(A)- Water is not suitable for fires involving oil and petrol.
Reason(R)- Water sinks below the oil layer and oil keeps on burning on the top.
14. Assertion(A)- Charcoal does not form a flame.
Reason(R)- Charcoal is a combustible substance.
15. Assertion(A)- CNG is a cleaner fuel.
Reason(R)- CNG produces a very small amount of harmful products and is less polluting.
ANSWERS
1. Inflammable substances
2. kJ/kg
3. Phosphorus
4. Water
5. Carbon
6. nuclear reaction
7. ignition temperature
8. fuel, oxygen, heat
9. all of these
10. ignition temperature is not reached due to the presence of water
11. c
12. e
13. a
14. b
15. a
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