Which is the best fire extinguisher for fires involving electrical equipment and inflammable materials like petrol?
Fill in the blanks with suitable words
(a)A fuel must be heated to its____ before it starts burning.
(b)The most common supporter of combustion around us is ____
(c)The fire produced by burning oil cannot be controlled by____
(d)A liquid fuel used in homes is____
(e)The amount of heat evolved when 1kg of fuel is burnt completely is called its____
(f)The substance which vaporize during, give____
(g)Burning of wood and coal causes____ of air.
(a) What are fuels? Name any two common fuels.
(b)State any four characteristics of an ideal fuel (or good fuel).
(a) Define the calorific value of a fuel.
(b)“The calorific value of LPG is 55000KJ/kg”. What does it mean?
What is meant by explosive combustion (or explosion)? Give one example of explosive combustion (or explosion).
(a) What does a Fire Brigade do when it arrives at a place where a building is on fire.
(b)Describe one method of putting out a fire caused by burning wood or paper.
Explain why, we are advised not to sleep in a room having closed doors and windows, with a coal fire burning inside.
(a) What is a flame? What type of substance, on burning, gives a flame?
(b)What is the difference between the burning of a candle and the burning of fuel like coal?
If you see a person whose clothes are on fire, how will you extinguish the fire? Give a reason for your answer.
Name the various zones of a candle flame. Which zone(or part) of a candle flame is the least hot(or coldest)?
In which zone of a candle flame: (a) partial combustion of fuel takes place, and (b) complete combustion of fuel takes place?
Explain why, when a burning candle is covered with an inverted gas jar, the candle gets extinguished after some time.
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