Combustion And Flame Important Questions And Answers
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Q1. Which fuels are used in the rural areas of our country?
Answer: Wood, agricultural residues, and cow dung cakes.
Q2. Which of the following solid fuels has the highest calorific value: cow dung cakes, coal, wood?
Answer: Coal.
Q3. Name the liquid fuel used in Indian households.
Answer: Kerosene.
Q4. Name three liquid fuels.
Answer: Kerosene, petrol, diesel.
Q5. What is produced when fuels burn?
Answer: Light and heat.
Q6. What is ignition temperature?
Answer: Ignition temperature is the minimum temperature at which a substance catches fire in the presence of oxygen.
Q7. Name two liquid substances with very low ignition temperature.
Answer: Alcohol and ether.
Q8. Which type of fire extinguisher is used to extinguish electrical fires?
Answer: Carbon tetrachloride extinguisher.
Q9. What is combustion?
Answer: Combustion is a process in which a substance burns in oxygen to produce heat and light.
Q10. Define calorific value of a fuel.
Answer: Calorific value is the amount of energy obtained from the complete combustion of 1 kilogram of a substance.
Q11. Which fire extinguisher is used to extinguish oil fires?
Answer: Foam type extinguisher.
Q12. Why is charcoal considered a better fuel than wood?
Answer: Charcoal has a higher calorific value than wood, making it a better fuel.
Q13. Name the regions of a candle flame.
Answer: Cool inner zone, middle zone, outer luminous zone.
Q14. Name two substances used for extinguishing fires.
Answer: Water, foam.
Q15. Name any three combustible substances.
Answer: (1) Paper (2) Wood (3) Cooking gas.
Q16. What is fuel? In which different states are fuels found?
Answer: Fuel is a substance that produces heat and light upon burning. Fuels are found in three states:
1. Solid (e.g., wood, coal, charcoal)
2. Liquid (e.g., petrol, kerosene, diesel)
3. Gas (e.g., natural gas, coal gas, biogas).
Q17. How would you prove that air is necessary for combustion?
Answer: To prove that air is necessary for combustion, cover a burning piece of coal or wood with a glass jar. The flame will extinguish after a while as the oxygen inside the jar is depleted. If the jar is lifted and air is allowed to enter, the material will ignite again, proving that oxygen is essential for combustion.
Q18. How can a fire caused by an accident be controlled?
Answer: A fire caused by an accident can be controlled by removing any one of the essential conditions for combustion:
(a) Stop the supply of oxygen.
(b) Cool down the combustible material or reduce its ignition temperature.
(c) Remove the combustible material to prevent the fire from spreading.
Q19. Why do goldsmiths use blowpipes?
Answer: Goldsmiths use blowpipes to direct the hottest part of the flame onto the gold. This increases the intensity of the fire, melting the gold or silver. The blowpipe allows unburnt carbon particles to ignite in the presence of sufficient oxygen, making the flame hotter.
Q20. Why don’t combustible substances catch fire on their own?
Answer: Combustible substances do not catch fire on their own because their ignition temperature is higher than the ambient temperature. They only ignite when the temperature reaches or exceeds their ignition temperature.
Q21. Why does a matchstick ignite when rubbed against the side of a matchbox?
Answer: When a matchstick is rubbed against the rough surface of a matchbox, the friction generates heat. This heat increases the temperature of the chemicals at the tip of the matchstick to their ignition point, causing them to ignite.
Q22. What is fire fighting?
Answer: Fire fighting refers to the process of extinguishing or controlling fires. Fires can occur due to accidents, short circuits, or human negligence. For combustion, three elements are needed: a combustible material, oxygen (air), and heat. To extinguish a fire, the flow of air or oxygen should be cut off.
Q23. What do you do to extinguish a fire?
Answer: To extinguish a fire, substances like carbon dioxide, water, or sand can be used to cut off the supply of air. Fires can start accidentally or due to human negligence, and preventing the supply of oxygen can help in controlling the fire.
In this post you will find some important questions and answers related to combustion and flame. Combustion and Flame Question Answer Combustion and Flame Class 8 Question Answer Combustion and Flame Class 8 Notes Dahan Aur Jwala Class 8 Question Answer Class 8th Science Chapter 6: Very important questions and answers related to combustion and flame have been given. If you find these answers useful, share them with your friends and if you want to know or ask something regarding this then make sure to ask by commenting below.