Fire: Friend and Foe – NCERT Solutions

Q. Mark the correct answer in each of the following:

1. Early man was frightened of
   1. Lightning and volcanoes.
   2. The damage caused by them.
   3. Fire
2. Fire is
   1. energy.
   2. heat and light.
   3. the result of a chemical reaction.

Answer

• Fire
• Fire is the result of a chemical reaction.

Q. From the boxes given below choose the one with the correct order of the following sentences:

(i) That is fire.
(ii) A chemical reaction takes place.
(iii) Energy in the form of heat and light is released.
(iv) Oxygen combines with carbon and hydrogen.

• (i) (ii) (iii) (iv)
• (ii) (iii) (i) (iv)
• (iv) (iii) (ii) (i)
• (iv) (ii) (iii) (i)

Ans. (iv) (ii) (iii) (i)

Q. What do you understand by the ‘flash point’ of a fuel?

Ans. The temperature at which a fuel begins to burn is called its ‘flash point’.

Q. What are some common uses of fire?

Ans. Fire is commonly used to cook food, warm our homes in winter and to generate electricity.

Q. In what sense is it a ‘bad master’?

Ans. Fire is a bad master, a dangerous enemy, if it goes out of control.

Q. Match items in Column A with those in Column B.

A	B
fuel	lighted matchstick
oxygen	air
heat	coal
	burning coal
	wood
	smouldering paper
	cooking gas

Answer

fuel	coal, wood, cooking gas
oxygen	air
heat	lighted matchstick, burning coal, smouldering paper

Q. What are the three main ways in which a fire can be controlled or put out?

Ans. We can control fire in three ways by taking away the fuel, by preventing oxygen from reaching it, and by removing the heat.

Q. Match items in Column A with those in Column B.

A	B
(i) To burn paper or a piece of wood,	• it absorbs heat from the burning material and
(ii) Small fires can be put out	• lowers the temperature.
(iii) When water is spread on fire,	• reduces the risk of fire.
(iv) A carbon dioxide extinguisher is the best thing	• with a damp blanket.
(v) Space left between buildings	• we heat it before it catches fire.
	• to put out an electrical fire.

Answer

1. To burn paper or a piece of wood, we heat it before it catches fire.
2. Small fires can be put out with a damp blanket.
3. When water is spread on fire, it absorbs heat from the burning material and lowers the temperature.
4. A carbon dioxide extinguisher is the best thing to put out an electrical fire.
5. Space left between buildings reduces the risk of fire.

Q. Why does a burning candle go out when you blow on it?

Ans. When we blow on a burning candle, we remove the hot air burning the flame. Thus, the temperature falls below the flash point.

Q. Spraying water is not a good way of putting out an oil fire or an electrical fire. Why not?

Ans. If water is sprayed on oil fire, oil floats on the top and continues to burn. Secondly, water can spread the fire. If a person throws water on electrical fire, he might get an electric shock and be killed.

Q. What are some of the things you should do to prevent a fire at home and in the school?

Ans. Fire fighting things should be kept ready at home as well as in school. Electrical appliance should be properly wired, earthed and insulated.

Q. 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

1. Fire is the result of a chemical reaction.
2. Wood, coal, cooking gas and petrol are some examples of fuel.
3. Oxygen comes from the air.
4. When you blow on the smouldering paper, it often bursts into flame.
5. To burn a piece of paper or wood we heat it before it catches fire.
6. Every fuel has a particular temperature at which it begins to burn.

Q. Fill in the blanks in the sentences below with words from the box. You may use a word more than once.

carbon, cause, fire, smother

1. Gandhiji’s life was devoted to the _____________ of justice and fair play.
2. Have you insured your house against ______________?
3. Diamond is nothing but ______________ in its pure form.
4. If you put too much coal on the fire at once you will ______________ it.
5. Smoking is said to be the main _____________ of heart disease.
6. When asked by an ambitious writer whether he should put some ______________ into his stories, Somerset Maugham murmured, “No, the other way round”.
7. She is a _______________ copy of her mother.
8. It is often difficult to _______________ a yawn when you listen to a long speech on the value of time.

Answer

1. cause
2. fire
3. carbon
4. smother
5. cause
6. fire
7. carbon
8. smother

Q. One word is italicised in each sentence. Find its opposite in the box and fill in the blanks.

spending, shut, destroy, subtract, increase

1. You were required to keep all the doors open, not _____________ .
2. PUPIL: What mark did I get in yesterday’s Maths test?
   TEACHER:You got what you get when you add five and five and _____________ ten from the total.
3. Run four kilometres a day to preserve your health. Run a lot more to _____________ it.
4. If a doctor advises a lean and lanky patient to reduce his weight further, be sure he is doing it to _____________ his income.
5. The world is too much with us; late and soon. Getting and _____________ we lay waste our powers.

Answer

1. shut
2. subtract
3. destroy
4. increase
5. spending

Q. Use the words given in the box to fill in the blanks in the sentences below:

across, along, past, through

1. The cat chased the mouse ___________ the lawn.
2. We are not allowed to cross the frontier. So we drove ___________ it as far as we could and came back happy.
3. The horse went ___________ the winning post and had to be stopped with difficulty.
4. It is not difficult to see ___________ your plan. Any one can see your motive.
5. Go ___________ the yellow line, then turn left. You will reach the post office in five minutes.

Answer

1. across
2. along
3. past
4. through
5. along