Text Book Back Questions and Answers - Chapter 3 Air We Breath Term 3 4th Science Guide Samacheer Kalvi Solutions - SaraNextGen [2024-2025]

Updated On May 15, 2024

By SaraNextGen

Chapter 3 - Air We Breath - Term 3 - 4th Science Guide Samacheer Kalvi Solutions

Text Book Back Questions and Answers
I. Choose the correct answer :
Question $1 .$
Air is a
(a) Mixture
(b) Compound
(c) Complex
Answer:
(a) Mixture

Question $2 .$
Percentage of oxygen in air is about
(a) 21
(b) 78
(c) 1
Answer:
(a) 21

Question $3 .$
Root nodules of some plants contain .
(a) Oxygen
(b) Nitrogen
(c)Neon
Answer:
(b) Nitrogen

Question $4 .$
The major reason for air pollution is
(a) Waste
(b) Smoke
(c)Water vapour
Answer:
(b) Smoke

II. WHO AM I?
Question $1 .$
I am a mixture of gases.
Answer:
Air

Question $2 .$
I give you oxygen.
Answer:
plants

Question $3 .$
I am not the supporter of burning.
Answer:
Nitrogen

Question $4 .$
You can help me to decrease pollution by riding on me.
Answer:
Bicycle

III. Write 'True' or 'False' :
Question $1 .$
plants need nitrogen for their growth.
Answer:
True

Question $2 .$
Air is made up of oxygen only.
Answer:
False

Question $3 .$
The gas used for burning things is argon.
Answer:
False

Question $4 .$
Carbonated drinks are bad to health.
Answer:
True

IV. Match the following : 
Question 1. 

Answer:

V. Fill in the blanks :
Question $1 .$
Air is a mixture of many ______
Answer:
Gases

Question $2 .$
Amount of carbon dioxide in the air is _____ $-\%$
Answer:
$0.03$

Question $3 .$
We inhale ______ gas.
Answer:
Oxygen

Question $4 .$

______ is used in fire extinguishers.
Answer:
Carbon dioxide

VI. Answer the following questions in brief :

Question $1 .$
What are the importance of air in our daily life?
Answer:
- Oxygen present in air is needed for respiration.
- We can speak and hear the sound only when there is air around.
- Air helps in the dispersal of seeds for plant reproduction.
- Monsoon and rain occurs due to the wind action.
- Air regulates the atmospheric temperature.

Question $2 .$
What are the components of air?
Answer:
Components of air are
- Nitrogen
- Argon
- Carbon dioxide
- Other gases

Question $3 .$
What are the adverse effects of air pollution?
Answer:
- Global warming
- Formation of smog,
- Formation of acid rain
- Aerosol formation
- Depletion of ozone

Question $4 .$
List uses of oxygen.
Answer:
- All living things use oxygen for breathing.
- Oxygen is essential for burning.
- Oxygen cylinders are used in hospitals to enable the patients to breathe when they cannot breathe normally.
- Oxygen is used in gas welding.

VII. Give short answers :
Question $1 .$
How can we reduce air pollution?

Answer:
Air pollution can be reduced by the following steps.
1. Alternative source of energy (E.g. Solar energy) should be used.
2. Air filters should be used to prevent harmful gases mixing with air.
3. Smoke emission test and certification of motor vehicles must be enforced.
4. More trees should be planted to absorb carbon dioxide.

Question $2 .$
What are the diseases caused due to air pollution?
Answer:
Air pollution cause irritation in the eyes, nose and throat. Air pollution can also produce wheezing, coughing and breathing problems in humans.
Some of the major effects of air pollution on human beings are:
- Respiratory diseases.
Example: Flu, Tuberculosis
- Cardiovascular damage.
- Fatigue, headaches and anxiety.
- Nervous system damage.

Question 3 .
List out the uses of carbon dioxide.
Answer:
- Carbon dioxide helps plants in photosynthesis.
- It is used in fire extinguishers.
- It is used in refrigerators as dry ice for cooling purpose.
- It is used to make plastics and polymers.

InText Questions and Answers
Activity (Text Book Page No. 88)
Question $1 .$
Take a squeezable bottle. Make a hole on the lid and close the bottle tightly. Bring the bottle near your face and press the bottle. What do you feel?
Answer:
Air will come rushing out of the bottle.

Let us do (Text Book Page No. 89)

From the given objects, find out the objects which has air in it.

Answer:

Let us do (Text Book Page No.90)
Tick $(\checkmark)$ the objects which gives out water vapour.

Question $1 .$

Answer:

Activity (Text Book Page No.91)
Question $1 .$
Write the percentage of the gases present in air.

Answer:

Activity (Text Book Page No.91)
Question $1 .$
You might have seen some huge colourful balloons flying high in malls. Those balloons are filled with nitrogen gas. Write the reason for filling nitrogen gas in balloons.
Answer:
The amount of nitrogen present in air is about $78 \%$ so it will float in air and will float upwards and it is also non-flammable gas.

Activity (Text Book Page No.93)
Classify the following
(Dog, cat, Coconut tree, monkey, brinjal plant, papaya plant)

Question $1 .$

Answer:

Activity (Text Book Page No.95) 
Tick (✓) the causes of global warming

Answer:

Activity (Text Book Page No.96)
Question $1 .$
Write slogans on harmful effects of air pollution in a chart and stick it on the display board

Answer:

1. Don't be mean, keep air clean
2. Spread solution, not Pollution
3. Give trees a lot of care, so you can breath fresh air
4. Say Loudly 'No' to air pollution

Additional Questions and Answers
I. Choose the correct answers :
Question $1 .$

_______ is important for all living creatures.
(a) Dust
(b) Pure air
(c) Unclean air
Answer:
(b) Pure air

Question $2 .$
Air has no______ $\&$ ______
(a) smell
(b) colour
(c) smell \& colour
Answer:
(c) smell \& colour

Question $3 .$

______ gas is filled in tyres of vehicles.
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
Answer:
(b) Nitrogen

Question $4 .$
_______is used in gas welding, medicine manufacturing, constructions and transportation.
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
Answer:
(a) Oxygen

II. Fill in the blanks :

Question $1 .$
_______present in the air is needed for respiration.(Oxygen / Helium)
Answer:
Oxygen

Question $2 .$
Monsoon and rain occurs due to the _______(wind action / sun action)
Answer:
wind action

Question $3 .$
Composition of the component of air _______ from place to place. (vary / Constant)
Answer:
vary

Question $4 .$
_______ is the main component of air. (Carbon dioxide / Nitrogen)
Answer:
Nitrogen

Question $5 .$
The Scottish chemist _______ discovered carbon dioxide is present in air. (Joseph priestly / Joseph black)
Answer:
Joseph black

III. True or False :
Question $1 .$
All living things use oxygen for breathing.
Answer:
True

Question $2 .$
The main component of air is oxygen
Answer:
False

Question $3 .$
Plants need nitrogen for growth.
Answer:
True

Question $4 .$
Nitrogen is essential for burning
Answer:
False

Question $5 .$
Air is important for ships and boats to sail.
Answer:
True

IV. Match the following:
Question $1 .$

Answer:

1. $-\mathrm{d}$
2. $-\mathrm{c}$
3. $-\mathrm{e}$
4. $-b$
5. $-a$
 

V. Answer the following:
Question $1 .$
What is the mixture of air?
Answer:
The air consists of a mixture of gases oxygen, carbon dioxide, nitrogen, water vapour, dust and smoke.

Question $2 .$
What is moving air called?
Answer:
Moving air is called wind.

Question $3 .$
Do sailors need the help of wind to sail?
Answer:
Yes. Ships and boats sail on the sea with the help of the wind.

Question $4 .$
Name two example for wind instruments.
Answer:
The nathaswaram and the flute are some of the examples for wind instrument.

Question $5 .$
Which gas is essential for burning?
Answer:
Yes, Oxygen is very essential for burning.

Question $6 .$
What was the old name of nitrogen?
Answer:
"Noxious air"

Question $7 .$
What is the presence of harmful substance in the air called?
Answer:
Pollution.

Question $8 .$
How do we get cool water from a clay water pot on hot sunny days?

Ans. Clay pot has thousands of tiny pores through which water seeps out. This causes cooling effect.

VI. Answer in detail :
Question $1 .$
Write a note on nitrogen
Answer:
- The amount of nitrogen present in air is about $78 \%$
- It is used to fill up food packages to extend their shelf life.
- Liquid nitrogen is used to store living cells.
- Plants need nitrogen for their growth.
- We can see root nodules containing nitrogen in some plants.
- Nowadays people use nitrogen gas to fill the tyres of their vehicles.
- Some compounds of nitrogen are used as explosives also.

Question $2 .$
Explain carbon dioxide and its uses.
Answer:
The amount of carbon dioxide present in air is only $0.03 \%$. Though it is less in percentage, its uses are more and essential. It can be tested with lime water. The lime water changes from colourless to milky.
Uses of carbon dioxide:
- Carbon dioxide helps plants in photosynthesis.
- It is used in fire extinguishers.
- It is used in refrigerators as dry ice for cooling purposes.
- It is used to make plastics and polymers.