1. Define combustion. 2. Give two examples of non-combustible substances. 3. What are the factors essential for combustion? 4. What do you mean by ignition temperature? 5. Which type of pollution occurs on burning wood? 6. What are inflammable substances? 7. What would you do when the clothes of a person catch fire? 8. How is CO2 able to control fire? 9. Write a difference between burning of a candle and the burning of coal. 10. Why is food regarded as a fuel for our body? 11. Which zone of a flame does a goldsmith use for melting gold and silver and why? 12. How can water boil in a paper cup without burning it? 13. What are the three zones of a flame? Draw a labelled diagram of a candle flame. 14. Why does a matchstick start burning on rubbing it on the side of the matchbox 15. Give reasonsa. LPG is a better domestic fuel than wood. b. Water is not used to control fires involving electrical equipment. c. Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminum pipe does not. d. Special care should be taken to store kerosene oil. 16. Explain how water is able to control fires? 17. What is calorific value of fuel? Write its unit. 18. Why is it difficult to burn is a heap of green leaves but easy to burn dry leaves? 19. What are the characteristics of an ideal fuel? 20. Why is L.P.G labeled as inflammable substance? 21. How does water help to extinguish fire? 22. Underline the substances which will produce flame on burning and give reasons Charcoal, molten wax, paper, coal, mustard oil 23. Draw a well labeled diagram of the flame of a candle and answer the following (a) Which zone is luminous and why? (b) Why is the innermost zone black in colour and the coldest zone? (c) Which zone is called the zone of complete combustion and why?​  

Dear Student ,

Combustion can be defined as burning of any substance in presence of atmospheric oxygen. The following reaction shows a combustion reaction wherein methane is burnt in atmospheric oxygen to form carbon dioxide and water vapour.

CH4 + 2O2 → CO2 + 2H2O

Combustion is an exothermic process i.e., the process is accompanied with the evolution of heat. The release of heat may or may not result in the production of light. Thus, two important things required for the process of combustion to take place are a fuel (combustible substance) and supporter of combustion (oxygen).
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