Working with the Text –
Answer the following questions
1. What do you understand ‘by flash point’ of a fuel
Ans. Flash point is the temperature at which a fuel begins to make fire is called ‘flash point. In the presence of fuel, and oxygen all on a sudden the fuel will not burn itself. It must have that very temperature which will begin fire in fuel. This is termed as ‘flash point’.
2. i) What are some common uses of fire?
Ans. We use fire for various purposes. We use fire -
a) To cook our daily food
b) To protect ourselves from cold.
c) To produce light at night.
d) To generate electricity.
ii) In what sense is it a “bad master”?
Ans. Fire has its negative sides also. If we are unable to control fire it can be a horrible entity. The deaths all around the world caused by various reasons include fire to be the prime. Carelessness, lacuna of the knowledge about fire safety and avoiding fire safety rules cause huge deaths. Apart from these fire caused in the forests destroys vast areas.
3. Match items in column A with those in column B
i) Fuel -Lighted match stick
ii) Oxygen - air
iii) Heat -coal
- Burning coal
- Smouldering paper.
- Cooking gas
Ans. I) Fuel – coal, wood, cooking gas
ii) Oxygen – air
iii) Heat – lighted matchstick, burning coal, smouldering paper.
4) What are the three main ways in which a fire can be controlled or put out?
Ans. As three things help us to make fire, we can use those very three things to control or put out fire.
Firstly, if we stop the supply of oxygen to the fire, it will stop. We can do it by using the spray of carbon-di-oxide or a damp blanket on the fire.
Secondly – we can remove the heat from fire and put it out or control it. We can do this by blowing air to the burning candle on fire. We can use water to remove the heat. In this way the temperature will go down the flash point’ and we can control or put out the fire.
Thirdly we can control or put out fire by removing fuel from the fire. We can remove, oil, wood, plastic, cooking gas etc. to do so.
5. Match the items in Box ‘A’ with those in Box ‘B’
i) To burn paper or a piece of wood -----------
ii) small fires can be put out ---------------------
iii) When water is spread on fire.---------------
iv) A carbon di-oxide extinguisher is the best thing ------------------------
v) Space left between buildings ----------------
We heat it before it catches fire
With a damp blanket
It absorbs heat from the burning material and lowers the temperature
To put out an electrical fire.
Reduces the risk of fire
6. Why does a burning candle go out when you blow on it?
Ans. To make fire ‘heat’ is very important. Likewise to put out fire also ‘heat’ is vital. So, when we blow air on a candle flame, the candle flame goes down below the temperature of ‘flash point’ and the candle flame goes out.
Q.7. Spraying water is not a good way of putting out an oil fire or an electrical fire. Why not?
Ans. For both oil fire and electrical fire water is not the good way.
For oil, water is not good because oil floats a water. So, the flame will also move on water and keep burning. It will move various places and increase the risk of fire.
Water is not the right way for electric fire because water is a good conductor of electricity. If anyone tries to put out an electric fire by spraying water, the person will get an electric shock and might be killed.
A.8. What are some of the things you should do to prevent a fire at home and in school?
Ans. “Prevention is better than cure”. Indeed we can prevent fire at home and in the school by following the ways given below-
a) Placing smoke alarms we can prevent fire.
b) keeping fire extinguisher to prevent fire.
c) using MCBs to protect from fire.
d) checking gas cylinder and tube time to time
e) keeping inflammable items at a safe place.
f) changing the old electric wires.
g) not keeping furniture near the room heaters.
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