VERY SHORT ANSWER TYPE QUESTIONS
Q. 1. What are fuels?
Ans. The substances which provide heat and light are called fuels.
Q. 2. Name two fuels that are used in your homes.
Ans. (i) L.P.G (ii) Kerosene.
Q. 3. What fuels are used for running automobiles?
Ans. Petrol, diesel and CNG.
Q. 4. What is the full form of CNG?
Ans. CNG stands for Compressed Natural Gas.
Q. 5. What is the difference between burning of a candle and burning of coal?
Ans. A candle burns with a flame whereas coal does not.
Q. 6. Classify the fuels.
Ans. The fuels are classified into solid, liquid and gas.
Q. 7. What are combustible substances?
Ans. The substances that undergo combustion are called combustible substances.
Q. 8. Do all the fuels burn with a flame?
Ans. No, all the fuels do not burn with a flame.
Q. 9. What are the products of combustion?
Ans. Carbon dioxide, water vapour, heat and light.
Q . 10. Name some combustible substances.
Ans. Wood, paper, kerosene oil, charcoal etc.
Q. 11. Write the names of some uncombustible substances.
Ans. Mud, stone, glass etc.
Q . 12. On the basis of the combustion classify the substances.
Ans. These are two types of substances: (i) Combustible (ii) Non‑combustible
Q . 13. What is the source of heat and light in the sun?
Ans. In the sun, heat and light are produced by nuclear reactions.
Q . 14. What do you mean by an ignition temperature?
Ans. The lowest temperature at which any substance catches fire is called its ignition temperature.
Q . 15. Do all the substances catch fire at the same temperature?
Ans. No, all the substances do not catch fire at the same temperature. Different substances catch fire at different temperature.
Q . 16. What are inflammable substances?
Ans. The substances which have very low ignition temperature and can catch fire easily with a flame are called inflammable substances.
Q . 17. Mention some examples of inflammable substances.
Ans. Petrol, alcohol and LPG etc.
Q . 18. Name the substances used to extinguish fire.
Ans. Water, sand and fire extinguishers.
Q . 19. Are these substances used to extinguish all the types of fire?
Q . 20. What substances are used to extinguish fire in case of electric short circuit?
Ans. Sand or soil and CO2.
Q . 21. Does your city/town have a fire brigade station?
Ans. Yes, there is a fire brigade station in my city.
Q . 22. What are the essential requirements for producing fire?
Ans. There are three requirements to produce fire:
(ii) Air to supply oxygen
(iii) Ignition temperature.
Q . 23. What is the principle to extinguish fire?
Ans. Fire can be controlled by removing one or more of the requirements—air, fuel or heat.
Q . 24. Which is the most common fire extinguisher?
Ans. Water is the most common fire extinguisher.
Q . 25. Write the name of different types of fire extinguisher.
Ans. (i) Soda‑acid (contains baking soda and acid) fire extinguisher.
(ii) Fire extinguisher cylinders having CO2 stored at high pressure
Q . 26. How many types of combustion are there?
Ans. There are three types of combustion:
(i) Rapid combustion
(ii) Spontaneous combustion and
Q . 27. What is flame?
Ans. The burning of vapours forms flame.
Q . 28. What is the colour of LPG flame?
Ans. Blue colour.
Q . 29. What is the colour of candle flame?
Ans. Yellow flame.
Q . 30. What type of substances produce flame?
Ans. The substances which vapourise during burning give flame.
Q . 31. Give examples of the substances which give flame.
Ans. Kerosene oil and molten wax.
Q . 32. Why does charcoal not produce flame?
Ans. Charcoal does not vapourise, so it does not produce a flame.
Q . 33. What are the different zones of flame?
Ans. There are three zones of flame:
(i) Non‑luminous zone
(ii) Luminous zone and
(iii) Dark zone.
Q . 34. Which zone of flame has highest temperature?
Ans. Non‑luminous zone.
Q . 35. What do you mean by deforestation?
Ans. The cutting of trees is called deforestation.