CBSE Class 8 Science - Combustion and Flame - Worksheet-2

Fill in the blanks with suitable words.

1. ________ gas in air is essential for combustion.

2. A chemical process in which a substance reacts with oxygen to give off heat is called __________.

3. During the process of combustion, _______ and light are given out.

4. The type of combustion in which material suddenly bursts into flames, without any apparent cause is called __________ combustion.

5. The lowest temperature at which a substance catches fire is called its _________ temperature.

6. _________ substances have very low ignition temperature.

7. ________ is commonly used to control fires. However, it cannot be used to control fires involving electrical equipment or oils.

8. Increased percentage of _________ in the air has been linked to global warming.

9. In this type of combustion, all of a sudden reaction results in heat, light and sound. We are talking about _______.

10. When something is burnt, a hot luminous gas emerges out of the substance. This gas is called as _______.

11. The substances which ________ during burning, give flames.

12. Outermost zone of a flame is _____ in colour and is the hottest amongst all the zones.

13. Middle zone is ________ in colour and is moderately hot.

14. The amount of heat produced on complete combustion of 1 kg of a fuel is called its _______ value.

15. Between LPG and wood, _______ pollutes less on combustion.

16. Carbon dioxide is widely used to control fire. CO₂ being ________ than oxygen, covers the fire like a blanket.

Answers:

1. Oxygen

2. Combustion

3. heat

4. spontaneous

5. ignition

6. Inflammable

7. Water

8. carbon dioxide

9. explosion

10. flame

11. vaporise

12. blue

13. yellow

14. calorific

15. LPG

16. heavier

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