Class-6 Science, Chapter-15 Air Around Us Aditional exercises with solutions in line with NCERT book / CBSE Syllabus
Chapter 15
Air Around us
=========================================================
Exercises from
textbook
Additional
Exercises
Tables from
Textbook
Activities/Projects
Additional Exercises
Choose the correct answer:
1-
When do you notice the
presence of air?
a.
Leaves of trees rustle
b.
Clothes hanging on
cloth-line sway
c.
Pages of an open book
flutter
d.
All the above (√)
2-
Moving air makes it
possible to
a.
Fly kite
b.
Separate sand and saw
dust by winnowing
c.
Both a and b (√)
d.
None of the above
3-
Our earth is
surrounded by a thin layer of air called
a.
core
b.
Atmosphere (√)
c.
Ecosystem
d.
Crust
4-
The component of air which
takes up nearly four-fifth of the space that air fills
a.
Nitrogen (√)
b.
Oxygen
c.
Argon
d.
Smoke and dust
5-
Plants use this gas
for respiration.
a.
Carbon dioxide
b.
Agron
c.
Oxygen(√)
d.
Nitrogen
6-
Plants produce this
gas in photosynthesis.
a.
Oxygen (√)
b.
Carbon dioxide
c.
Nitrogen
d.
Smoke
1-
Air has no colour
and one can see through it.
2-
Air is a mixture
of many gases.
3-
When air comes in
contact with a cool surface, it condenses and drops of water appear on
the cooled surface.
4-
The presence of water
vapour in air is important for the water cycle in nature.
5-
Plants and animals
consume oxygen for respiration and produce carbon dioxide.
State whether the following statements are True or False:
1-
Air is a mixture of many
gases. True
2-
Dust particles are
always present in air. True
3-
The presence of dust
particles in air varies from time to time and place to place.True
4-
Plants consume carbon
dioxide for respiration. False
5-
Air is present in
water and soil. True
Match these column:
A
|
B
|
The envelop of air that surrounds
the earth.
|
Oxygen
|
The gas, which supports burning
and is necessary for living organisms.
|
Dissolved air
|
Aquatic animals use it in water
for respiration.
|
Space
|
Air in motion is called
|
Atmosphere
|
Air occupies
|
Wind
|
Ans-
A
|
B
|
The envelop of air that surrounds
the earth.
|
Atmosphere
|
The gas, which supports burning
and is necessary for living organisms.
|
Oxygen
|
Aquatic animals use it in water
for respiration.
|
Dissolved air
|
Air in motion is called
|
Wind
|
Air occupies
|
Space
|
Give one word for the following:
1-
Thin layer of earth
around us
Ans- Atmosphere
2-
Formation of droplets
of water on the cooled surface
Ans- Condensation
3-
The major part of air which
does not support burning
Ans- Nitrogen
4-
The atmospheric gas
that supports burning
Ans- Oxygen
Answer these questions:
Q. Why do mountaineers
carry oxygen cylinders with them, while climbing high mountains?
Ans- Mountaineers carry oxygen cylinders with them, while climbing high mountains because atmospheric oxygen decreases at higher altitudes because of decrease in atmospheric pressure.
Ans- Mountaineers carry oxygen cylinders with them, while climbing high mountains because atmospheric oxygen decreases at higher altitudes because of decrease in atmospheric pressure.
Q. Why do you see long
chimneys in factories?
Ans- Long chimneys in
factories take the harmful smoke and gases away from our noses and protect
humans from the harmful effects of the smoke and gases.
Q. Why should you not
breathe through mouth?
Ans- We should not
breathe through mouth because harmful dust particles may enter your body if we
do so. Our nose has fine hairs and mucus to prevent the entry of dust
particles.
Q. How do the
organisms that live inside the soil respire?
Ans- The organisms
that live inside the soil respire using the air present in the porous soil.
Q. How will you demonstrate
that plants roots respire using the air present in soil?
Ans- When the water is
poured on the lump of soil, it displaces the air, which is seen in the form of
bubbles. The plant roots which are inside the soil, respire in this air.
Q. Why do earthworms
come out of the soil only during heavy rains?
Ans- Earthworms make
holes in deep soil. This makes spaces available for air to move in and out of
the soil. When it rains heavily, water fills up all the spaces occupied by the air
in the soil. In this situation earthworms have to come out for respiration.
Q. Draw a diagram of
windmill and write its three uses?
Ans- The wind makes
the windmill rotate.
Following are uses of
windmill:
1-
To draw water from
tubewells
2-
To run flour mills.
3-
To generate electricity
Exercises from Textbook
1. What is the composition of air?
Ans- Dry air is contains Nitrogen (78%), Oxygen (21%), Argon (1%), Carbon-dioxide (0.03%), water vapours, dust, smoke and some other gases.
2. Which gas in the atmosphere is essential for respiration?
Ans- Oxygen gas in the atmosphere is essential for respiration.
3. How will you prove that air supports burning?
Ans- To prove that air supports burning, we will perform an experiment. We will arrange the setup as shown in the figure.
The candle blows out after sometime and the water level rises in the glass.
The rise in water level indicates that the air present in glass was used up by the candle. Hence air supports burning.
4. How will you show that air is dissolved in water?
Ans- We will perform an activity to show that air is dissolved in water.
We will slowly heat some water in a glass vessel. Well before the water begins to boil, wee observe tiny bubbles on the inner surface of vessel. These bubbles come from the air dissolved in water.
5. Why does a lump of cotton wool shrinks in water?
Ans- A lump of cotton wool contains air in the gap between fibers. When it is immersed in water, this air is replaced by water. Cotton wool becomes heavier and shrinks.
6. The layer of air around the earth is known as atmosphere.
7. The component of air used by green plants to make their food is carbon dioxide.
8. List five activities that are possible due to the presence of air.
Ans- Following are the five activities that are possible due to the presence of air:
1- Air helps in the movement of sailing yachts
2- Movements of gliders, parachutes and gliders is possible because of air
3- Birds, bats and insects can fly due to the presence of air.
4- Air helps in dispersal of seeds
5- Air helps in dispersal of pollens of several plants.
9. How do plants and animals help each other in the exchange of gases in the atmosphere?
Ans-
Plants make their own food and produce oxygen. Both plants and animals use oxygen for respiration and release carbon dioxide. But plants produce more oxygen than that they consume. The balance of oxygen and carbon dioxide in the atmosphere is maintained through respiration in plants and animals and by the photosynthesis in plants.
Suggested Projects and Activities
1-
List
three activities in which you can save water. For each activity describe how
would you do it.
2-
Collect
pictures relating to floods or drought from old magazines or news pares. Paste
them in your notebook and write about the problems that people would have
faced.
3-
Prepare
a poster on ways of saving water and display it on your school notice board.
4-
Write
a few slogans of your own on the topic ‘Save Water’.
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