NCERT Textbook: Fire: Friend & Foe | NCERT Textbooks & Solutions for Class 7 PDF Download

 Page 1


8
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smouldering:
burning slowly
without flame
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________________
Before you read
Fire is both useful and dangerous. What  is fire?
How did we discover it? How do we control it?
                Fire: Friend and Foe
arly man didn’t know what fire was,
but he must have seen the damage it
could cause. He must have watched lightning and
volcanoes long before he began to use fire himself.
Fire was powerful and dangerous, and he
was frightened.
Fire may have puzzled early man but we now
know that fire is the result of a chemical reaction.
When the oxygen in the air combines with carbon
and hydrogen in a fuel, a chemical reaction takes
place. Energy in the form of heat and light is
released in this process. This is what we call fire.
Three things are needed to make fire — fuel,
oxygen and heat. Wood, coal, cooking gas and
petrol are some examples of fuel. Oxygen comes
from the air. That is why, when you blow on
smouldering paper, it often bursts into flame. The
third thing needed to make fire is heat. Fuel and
oxygen do not make fire by themselves, or else a
newspaper or a stick lying in the open would catch
fire on its own. To burn a piece of paper or wood,
E
2022-23
Page 2


8
________________
________________
________________
________________
________________
smouldering:
burning slowly
without flame
________________
________________
________________
Before you read
Fire is both useful and dangerous. What  is fire?
How did we discover it? How do we control it?
                Fire: Friend and Foe
arly man didn’t know what fire was,
but he must have seen the damage it
could cause. He must have watched lightning and
volcanoes long before he began to use fire himself.
Fire was powerful and dangerous, and he
was frightened.
Fire may have puzzled early man but we now
know that fire is the result of a chemical reaction.
When the oxygen in the air combines with carbon
and hydrogen in a fuel, a chemical reaction takes
place. Energy in the form of heat and light is
released in this process. This is what we call fire.
Three things are needed to make fire — fuel,
oxygen and heat. Wood, coal, cooking gas and
petrol are some examples of fuel. Oxygen comes
from the air. That is why, when you blow on
smouldering paper, it often bursts into flame. The
third thing needed to make fire is heat. Fuel and
oxygen do not make fire by themselves, or else a
newspaper or a stick lying in the open would catch
fire on its own. To burn a piece of paper or wood,
E
2022-23
FIRE: FRIEND AND FOE/115
we heat it before it catches fire. We generally do it
with a lighted match. Every fuel has a particular
temperature at which it begins to burn. This
temperature is called the ‘flash point’ or ‘kindling
temperature’ of the fuel.
It is sometimes said that fire is a good servant
but a bad master. It only means that fire is very
useful as long as it is kept under control.
For instance, we use it to cook our food, warm
our homes in winter and to generate electricity.
But, on the other hand, if fire gets out of control it
can be very dangerous. Each year thousands of
homes and shops are damaged by fire. Vast areas
of forest are also destroyed and hundreds of
people are killed or injured.
Just 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.
________________
________________
________________
________________
________________
________________
generate:
produce
________________
________________
________________
________________
________________
________________
________________
_______________
2022-23
Page 3


8
________________
________________
________________
________________
________________
smouldering:
burning slowly
without flame
________________
________________
________________
Before you read
Fire is both useful and dangerous. What  is fire?
How did we discover it? How do we control it?
                Fire: Friend and Foe
arly man didn’t know what fire was,
but he must have seen the damage it
could cause. He must have watched lightning and
volcanoes long before he began to use fire himself.
Fire was powerful and dangerous, and he
was frightened.
Fire may have puzzled early man but we now
know that fire is the result of a chemical reaction.
When the oxygen in the air combines with carbon
and hydrogen in a fuel, a chemical reaction takes
place. Energy in the form of heat and light is
released in this process. This is what we call fire.
Three things are needed to make fire — fuel,
oxygen and heat. Wood, coal, cooking gas and
petrol are some examples of fuel. Oxygen comes
from the air. That is why, when you blow on
smouldering paper, it often bursts into flame. The
third thing needed to make fire is heat. Fuel and
oxygen do not make fire by themselves, or else a
newspaper or a stick lying in the open would catch
fire on its own. To burn a piece of paper or wood,
E
2022-23
FIRE: FRIEND AND FOE/115
we heat it before it catches fire. We generally do it
with a lighted match. Every fuel has a particular
temperature at which it begins to burn. This
temperature is called the ‘flash point’ or ‘kindling
temperature’ of the fuel.
It is sometimes said that fire is a good servant
but a bad master. It only means that fire is very
useful as long as it is kept under control.
For instance, we use it to cook our food, warm
our homes in winter and to generate electricity.
But, on the other hand, if fire gets out of control it
can be very dangerous. Each year thousands of
homes and shops are damaged by fire. Vast areas
of forest are also destroyed and hundreds of
people are killed or injured.
Just 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.
________________
________________
________________
________________
________________
________________
generate:
produce
________________
________________
________________
________________
________________
________________
________________
_______________
2022-23
116/HONEYCOMB
For example, we can take away the fuel. If the
fire has no fuel to feed on, no burning can take
place. W e often let a fire die out simply by not adding
more fuel to it.
The second way of putting out a fire is to
prevent oxygen from reaching it. No supply of
oxygen means no fire. Small fires can be put out
or ‘smothered’ with a damp blanket or a sack.
This stops oxygen reaching the burning material.
Sometimes, carbon dioxide is used to extinguish
fire. It does not allow oxygen to reach the
burning material.
The third way of putting out a fire is to remove
the heat. If the temperature can be brought down
below the flash point, the fuel stops burning. You
blow on a burning matchstick or a candle to put it
out. In doing so, you remove the hot air around
the flame bringing down its temperature below the
flash point, and the candle goes out. Sometimes,
water is sprayed on a fire. It absorbs heat from the
burning fuel and lowers the temperature. The
blanket of water also cuts off the supply of oxygen,
and the fire is extinguished.
Some fires cannot be put out with water. If water
is sprayed onto an oil fire, the oil will float to the
top of the water and continue to burn. This can be
very dangerous because water can flow quickly,
carrying the burning oil with it and spreading the
fire. Water should also not be used on fires caused
by electrical appliances. The person spraying water
might receive an electric shock and be killed. A
carbon dioxide extinguisher is the best thing to
fight an electrical fire.
add fuel to
the flames
(idiom): say
or do
something
that makes
people react
more strongly
and fiercely
smothered:
suffocated
(from lack
of air)
extinguish:
put out
________________
________________
________________
________________
________________
________________
_______________
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
2022-23
Page 4


8
________________
________________
________________
________________
________________
smouldering:
burning slowly
without flame
________________
________________
________________
Before you read
Fire is both useful and dangerous. What  is fire?
How did we discover it? How do we control it?
                Fire: Friend and Foe
arly man didn’t know what fire was,
but he must have seen the damage it
could cause. He must have watched lightning and
volcanoes long before he began to use fire himself.
Fire was powerful and dangerous, and he
was frightened.
Fire may have puzzled early man but we now
know that fire is the result of a chemical reaction.
When the oxygen in the air combines with carbon
and hydrogen in a fuel, a chemical reaction takes
place. Energy in the form of heat and light is
released in this process. This is what we call fire.
Three things are needed to make fire — fuel,
oxygen and heat. Wood, coal, cooking gas and
petrol are some examples of fuel. Oxygen comes
from the air. That is why, when you blow on
smouldering paper, it often bursts into flame. The
third thing needed to make fire is heat. Fuel and
oxygen do not make fire by themselves, or else a
newspaper or a stick lying in the open would catch
fire on its own. To burn a piece of paper or wood,
E
2022-23
FIRE: FRIEND AND FOE/115
we heat it before it catches fire. We generally do it
with a lighted match. Every fuel has a particular
temperature at which it begins to burn. This
temperature is called the ‘flash point’ or ‘kindling
temperature’ of the fuel.
It is sometimes said that fire is a good servant
but a bad master. It only means that fire is very
useful as long as it is kept under control.
For instance, we use it to cook our food, warm
our homes in winter and to generate electricity.
But, on the other hand, if fire gets out of control it
can be very dangerous. Each year thousands of
homes and shops are damaged by fire. Vast areas
of forest are also destroyed and hundreds of
people are killed or injured.
Just 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.
________________
________________
________________
________________
________________
________________
generate:
produce
________________
________________
________________
________________
________________
________________
________________
_______________
2022-23
116/HONEYCOMB
For example, we can take away the fuel. If the
fire has no fuel to feed on, no burning can take
place. W e often let a fire die out simply by not adding
more fuel to it.
The second way of putting out a fire is to
prevent oxygen from reaching it. No supply of
oxygen means no fire. Small fires can be put out
or ‘smothered’ with a damp blanket or a sack.
This stops oxygen reaching the burning material.
Sometimes, carbon dioxide is used to extinguish
fire. It does not allow oxygen to reach the
burning material.
The third way of putting out a fire is to remove
the heat. If the temperature can be brought down
below the flash point, the fuel stops burning. You
blow on a burning matchstick or a candle to put it
out. In doing so, you remove the hot air around
the flame bringing down its temperature below the
flash point, and the candle goes out. Sometimes,
water is sprayed on a fire. It absorbs heat from the
burning fuel and lowers the temperature. The
blanket of water also cuts off the supply of oxygen,
and the fire is extinguished.
Some fires cannot be put out with water. If water
is sprayed onto an oil fire, the oil will float to the
top of the water and continue to burn. This can be
very dangerous because water can flow quickly,
carrying the burning oil with it and spreading the
fire. Water should also not be used on fires caused
by electrical appliances. The person spraying water
might receive an electric shock and be killed. A
carbon dioxide extinguisher is the best thing to
fight an electrical fire.
add fuel to
the flames
(idiom): say
or do
something
that makes
people react
more strongly
and fiercely
smothered:
suffocated
(from lack
of air)
extinguish:
put out
________________
________________
________________
________________
________________
________________
_______________
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
2022-23
FIRE: FRIEND AND FOE/117
We spend millions of rupees each year in
fighting fires. And we spend more trying to find
new ways of preventing fires from happening
and getting out of control. On the whole, we have
learnt rather well to control fire and put it to good
use in our everyday life.
Long ago, there were no firemen. When fire
broke out, everybody became a firefighter.
People formed human chains (they still do if
required) and passed buckets of water from a
well or a pond to the blaze. Now there are laws
about building construction which ensure that
space is left between buildings to reduce
the fire risk. Every new building, especially a
public place, must ensure observance of fire
prevention norms. Bands of firefighting workers
with special equipment, known as fire
brigades, are there to put out fires. Firefighters
are highly trained people. They possess many
skills. They cut off electricity supply, knock
down dangerous walls, spray water and other
materials to bring fire under control.
They are also trained in first aid so that
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
bands: groups
equipment:
things needed
________________
________________
2022-23
Page 5


8
________________
________________
________________
________________
________________
smouldering:
burning slowly
without flame
________________
________________
________________
Before you read
Fire is both useful and dangerous. What  is fire?
How did we discover it? How do we control it?
                Fire: Friend and Foe
arly man didn’t know what fire was,
but he must have seen the damage it
could cause. He must have watched lightning and
volcanoes long before he began to use fire himself.
Fire was powerful and dangerous, and he
was frightened.
Fire may have puzzled early man but we now
know that fire is the result of a chemical reaction.
When the oxygen in the air combines with carbon
and hydrogen in a fuel, a chemical reaction takes
place. Energy in the form of heat and light is
released in this process. This is what we call fire.
Three things are needed to make fire — fuel,
oxygen and heat. Wood, coal, cooking gas and
petrol are some examples of fuel. Oxygen comes
from the air. That is why, when you blow on
smouldering paper, it often bursts into flame. The
third thing needed to make fire is heat. Fuel and
oxygen do not make fire by themselves, or else a
newspaper or a stick lying in the open would catch
fire on its own. To burn a piece of paper or wood,
E
2022-23
FIRE: FRIEND AND FOE/115
we heat it before it catches fire. We generally do it
with a lighted match. Every fuel has a particular
temperature at which it begins to burn. This
temperature is called the ‘flash point’ or ‘kindling
temperature’ of the fuel.
It is sometimes said that fire is a good servant
but a bad master. It only means that fire is very
useful as long as it is kept under control.
For instance, we use it to cook our food, warm
our homes in winter and to generate electricity.
But, on the other hand, if fire gets out of control it
can be very dangerous. Each year thousands of
homes and shops are damaged by fire. Vast areas
of forest are also destroyed and hundreds of
people are killed or injured.
Just 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.
________________
________________
________________
________________
________________
________________
generate:
produce
________________
________________
________________
________________
________________
________________
________________
_______________
2022-23
116/HONEYCOMB
For example, we can take away the fuel. If the
fire has no fuel to feed on, no burning can take
place. W e often let a fire die out simply by not adding
more fuel to it.
The second way of putting out a fire is to
prevent oxygen from reaching it. No supply of
oxygen means no fire. Small fires can be put out
or ‘smothered’ with a damp blanket or a sack.
This stops oxygen reaching the burning material.
Sometimes, carbon dioxide is used to extinguish
fire. It does not allow oxygen to reach the
burning material.
The third way of putting out a fire is to remove
the heat. If the temperature can be brought down
below the flash point, the fuel stops burning. You
blow on a burning matchstick or a candle to put it
out. In doing so, you remove the hot air around
the flame bringing down its temperature below the
flash point, and the candle goes out. Sometimes,
water is sprayed on a fire. It absorbs heat from the
burning fuel and lowers the temperature. The
blanket of water also cuts off the supply of oxygen,
and the fire is extinguished.
Some fires cannot be put out with water. If water
is sprayed onto an oil fire, the oil will float to the
top of the water and continue to burn. This can be
very dangerous because water can flow quickly,
carrying the burning oil with it and spreading the
fire. Water should also not be used on fires caused
by electrical appliances. The person spraying water
might receive an electric shock and be killed. A
carbon dioxide extinguisher is the best thing to
fight an electrical fire.
add fuel to
the flames
(idiom): say
or do
something
that makes
people react
more strongly
and fiercely
smothered:
suffocated
(from lack
of air)
extinguish:
put out
________________
________________
________________
________________
________________
________________
_______________
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
2022-23
FIRE: FRIEND AND FOE/117
We spend millions of rupees each year in
fighting fires. And we spend more trying to find
new ways of preventing fires from happening
and getting out of control. On the whole, we have
learnt rather well to control fire and put it to good
use in our everyday life.
Long ago, there were no firemen. When fire
broke out, everybody became a firefighter.
People formed human chains (they still do if
required) and passed buckets of water from a
well or a pond to the blaze. Now there are laws
about building construction which ensure that
space is left between buildings to reduce
the fire risk. Every new building, especially a
public place, must ensure observance of fire
prevention norms. Bands of firefighting workers
with special equipment, known as fire
brigades, are there to put out fires. Firefighters
are highly trained people. They possess many
skills. They cut off electricity supply, knock
down dangerous walls, spray water and other
materials to bring fire under control.
They are also trained in first aid so that
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
________________
bands: groups
equipment:
things needed
________________
________________
2022-23
118/HONEYCOMB
they can help people suffering from burns or
from the effects of smoke.
The discovery of fire and its uses helped early
man to cope with nature better and gradually
adopt a settled mode of life. Fire is still worshipped
in many parts of the world. Fire is indeed a friend
but, as we know, it can be a dangerous enemy
once it gets out of control.
Comprehension Check
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.
2. 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)
cope: deal
with; manage
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2022-23