Chapter 8 – Fire Friend and Foe Solutions
Question - 1 : - Mark the correct answer in each of the following.
(i) Early man was frightened of
(a) lightning and volcanoes
(b) the damage caused by them
(c) fire.
(ii) (a) Fire is energy.
(b) Fire is heat and light.
(c) Fire is the result of a chemical reaction.
Answer - 1 : -
(i) (c) fire.
(ii) (c) Fire is the result of a chemical reaction.
What do you understand by the ‘flash point of a fuel ?
Answer - 2 : -
Every fuel has a particular temperature. The temperature at which it begins to burn is called ‘flash point of a fuel.
Question - 3 : - (i) What are some common uses of fire ?
(ii) In what sense is it a “bad master”?
Answer - 3 : -
i) Fire is commonly used to cook our food, warm our homes in winter and to generate electricity.
(ii) It is a bad master if it gets out of control. Then it burns the things which it engulfs.
Question - 4 : - Match items in Column A with those in Column B.
Answer - 4 : - 
Question - 5 : - What are the three main ways in which a fire can be controlled or put out ?
Answer - 5 : -
Three things are needed to make fire-fuel, oxygen and heat. First as three things are needed to start a fire, there are three main ways in which a fire can be put out. In each, one of the three things needed for burning is taken away. For example, we can take away the fuel. If the fire has no fuel to feed on, no burning can take place. The second way of putting out a fire is to prevent oxygen from reaching it. No supply of oxygen means no fire. The third way is to remove the heat. If the temperature can be brought down below the flash point, the fuel stops burning.
Question - 6 : - Match the items in Box A with those in Box B | A
(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 dioxide extinguisher is the best thing
(v) Space left between buildings
| B · it absorbs heat from the burning material and · lowers the temperature. · reduces the risk of fire. · with a damp blanket. · we heat it before it catches fire. · to put out an electrical fire. |
Answer - 6 : -
(i) To burn paper or a piece of wood — we heat it before it catches fire.
(ii) Small fires can be put out — with a damp blanket.
(iii) When water is spread on fire — it absorbs heat from the burning material and lowers the temperature.
(iv) A carbon dioxidc extinguisher is the best thing — to put out an electrical fire.
(v) Space left between buildings — reduces the risk of fire.
Question - 7 : - Why does a burning candle go out when you blow on it?
Answer - 7 : -
When we blow on a burning candle,we remove the hot air around the flame. This causes fall in temperature below the flash point. So, the candle goes out.
Question - 8 : - Spraying water is not a good way of putting out an oil fire or an electrical fire. Why not?
Answer - 8 : -
If water is sprayed onto an oil fire, the oil will float on the top and continue to burn. Water can carry oil with it and continue to burn. Water should also not be used on fires caused by electrical appliances. The person might get an electric shock and get killed.
Question - 9 : - What are some of the things you should do to prevent a fire at home and in the school ?
Answer - 9 : -
At home we can prevent the fire if all the electrical appliances are earthed and insulated. There should always be a bucket of sand to put out.small fires. In the school, the training should be given to students how to put out fire. The school should also have fire extinguishers which should always be ready for use.
Question - 10 : - Read the following sentences.
To burn paper or a piece of wood, we heat it before it catches fire. We generally do it with a lighted match. Every fuel has a particular temperature at which it burns. The verbs in italics are in the simple present tense. When we use it, we are not thinking only about the present. We use it to say that something happens all the time or repeatedly, or that something is true in general. Find ten examples of verbs in the simple present tense in the text ‘Fire: Friend
and Foe’ and write them down here. Do not include any passive verbs.
Answer - 10 : -
1. This is what we call fire.
2. Oxygen comes from the air.
3. We use it to cook our food, warm our homes in winter and to generate electricity.
4. It is sometimes said that fire is a good servant but a bad master.
5. There are three main ways in which fire can be put out.
6. The third way of putting out a fire is to remove heat.
7. The blanket of water also cuts off the supply of oxygen, and the fire is extinguished.
8. We spend millions of rupees each year in fighting fire.
9. When we blow on a burning match stick, we remove the hot air around the flame.
10. Thus the candle goes out.