# HBSE 6th Class Science Solutions Chapter 15 Air Around Us

Haryana State BoardÂ HBSE 6th Class Science Solutions Chapter 15 Air Around Us Textbook Exercise Questions and Answers.

## Haryana Board 6th Class Science Solutions Chapter 15 Air Around Us

Exercises

Question 1.
What is the composition of air?
Answer:
The major components of air are:
(i) Nitrogen (78%)
(ii) Oxygen (21%)
(iii) Noble gases (0.9%)
(iv) Carbon dioxide (00.3%)
(iv) Other gases, dust particles and water vapours (0.01%) by volume.

Question 2.
Which gas in the atmosphere is essential for respiration?
Answer:
Oxygen gas in the atmosphere is essential for respiration.

Question 3.
How will you prove that air supports burning?
Answer:
Take two plastic bottles and remove their base with the help of a sharp knife. Take two candles and coverthese two burning candles with the plastic bottles. After some time, candles stop burning and water level rises up in the plastic bottles.

Now make several holes in one plastic bottle and cover the lighting candle with this bottle. We see that candle burns continuously. This candle gets air from different holes and burns continuously till it is completely finished. This activity shows that air supports burning.

Question 4.
How will you show that air is dissolved in water?
Answer:
Take some water in a beaker and heat it slowly on a tripod stand with gas burner. We see that tiny bubbles are sticking on it. These
bubbles are mainly of oxygen gas present in air, i which is dissolved in water. When we heat water, the air dissolved in water escapes out in the form of bubbles.
This shows that air is dissolved in water.

Question 5.
Why does cotton lump get sunk T in water?
Answer:
Cotton lump contains air in it. There are various spaces in which air is filled. When cotton lump is put into water, air present in the vacant space dissolved in water and cotton lump sank.

Question 6.
The layer of air around the earth is known as
Answer:
The layer of air around the earth is known as atmosphere.

Question 7.
The component of air used by green plants to make their food is
Answer:
Carbon dioxide is needed by green 1 plants to make their food.

Question 8.
List five activities that are possible due to presence of air.
Answer:
Activities that are possible due to presence of air are as follows:
(i) Windmill.
(ii) Movements of sailing yachts.
(iii) Flying of aeroplanes, birds, etc.
(iv) Dispersal of seeds.
(v) Watercycle.

Question 9.
How do plants and animals help each other in the exchange of gases in the atmosphere?
Answer:
Plants and animals help each other in exchange of gases. They are interdependent on each other. All the animals require oxygen for their survival. It helps breaking down digested food in the body and release energy. This process is called respiration. During respiration, carbon dioxide gas is produced.

Plants consume this carbon dioxide gas for preparing their own food and release oxygen. They also use some oxygen for respiration. This oxygen gas is used for animals in their respiration process. In this way, plants and animals help each other in the exchange of gases in the atmosphere.

HBSE 6th Class Science Air around us Important Questions and Answers

Very Short Answer Type Questions

Question 1.
Where do we get air?
Answer:
We get air from the atmosphere.

Question 2.
What is the use of air pressure?
Answer:
Air pressure is used in pumps.

Question 3.
The cover of air around the earth is called
Answer:
Atmosphere.

Question 4.
Air occupies and
Answer:
Space, mass.

Question 5
forms the earth atmosphere.
Answer:
Air.

Question 6.
What gases are found in the air?
Answer:
Air contains nitrogen, oxygen, carbon dioxide and inert gases and water vapours.

Question 7.
Which gas forms the largest part of the air?
Answer:
Nitrogen.

Question 8.
What part of the air is oxygen?
Answer:
Oxygen is l/5th part of the air.

Question 9.
What is the use of nitrogen in air?
Answer:
Nitrogen slows down the process of combustion.

Question 10.
State one biological importance of air dissolved in water.
Answer:
Dissolved air helps aquatic animals for breathing.

Question 11.
During photosynthesis, which gas is consumed?
Answer:
Carbon dioxide gas.

Question 12.
Which gas is released during photosynthesis?
Answer:
Oxygen gas.

Question 13.
Which gas is helpful for combustion?
Answer:
Oxygen gas.

Question 14.
When do plants release oxygen?
Answer:
Plants release oxygen during photosynthesis.

Question 15.
Name two variable components of air.
Answer:
(i) Nitrogen
(ii) Oyxgen.

Question 16.
Name two objects which are inflated by air.
Answer:
(i) Cycle tyre
(ii) Balloons.

Question 17.
Give the percentage composition of nitrogen and oxygen by volume in air.
Answer:
Nitrogen – 70% and oxygen – 21%.

Question 18.
Name two inert gases present in the air.
Answer:
(i) Argon
(ii) Neon.

Question 19.
Why do we need extra oxygen supply at high altitude?
Answer:
Because at high altitude air is thin.

Question 20.
Excepting oxygen and nitrogen, name two other gases present in the air.
Answer:
(i) Carbon dioxide
(ii) Argon.

Question 21.
Which component of the air is used in fire extinguishers?
Answer:
Carbon dioxide gas.

Question 22.
State one way in which air enters the air.
Answer:
Through respiration.

Question 23.
Why do we call neon and argon as inert gases?
Answer:
Because they do not react with any ; other element or compound in ordinary conditions.

Question 24.
Name two gases which can – damage historical monuments.
Answer:
(i) Nitrogen dioxide
(ii) Sulphur dioxide.

Question 25.
What is called wind?
Answer:
The moving air is called wind.

Question 26.
Name two properties of air.
Answer:
(i) Air occupies space
(ii) It has mass.

Question 27.
Write two importances of air in agriculture.
Answer:
(i) Air helps rotate wind-mill which is used to draw water from tube-wells.
(ii) Air helps in dispersion of seeds and ; pollen grains of flowers of several plants.

Question 28.
Give one important use of .! nitrogen.
Answer:
Nitrogen is used in the manufacture of fertilizers.

Question 29.
Name two major gases of air.
Answer:
Two major gases of air are:
(i) Nitrogen
(ii) Oxygen.

Short Answer Type Questions

Question 1.
Write the names of four main constituents of air.
Answer:
(i) Nitrogen
(ii) Oxygen
(iii) Carbon dioxide
(iv) Water vapours.

Question 2.
What are the uses of oxygen present in air?
Answer:
Uses of oxygen:
(i) Animals use oxygen for breathing and respiration.
(ii) Aquatic animals and plants use oxygen for breathing.
(iii) Mountaineers inhale oxygen at heights where air is thin.
(iv) Pure oxygen is used for artificial breathing in hospitals.
(v) Oxygen is used in oxy-acetylene torch for welding and cutting purposes.
(vi) Liquid oxygen is used as rocket fuels.

Question 3.
How can you show that air contains carbon dioxide?
Answer:
Take some lime water in a watch glass and keep it for a few hours in open air. A white crust is formed on the upper surface of the lime water. Lime water turns milky due to the presence of carbon dioxide in the air. This shows that air contains carbon dioxide.

Question 4.
Show that one-fifth volume of air is oxygen.
Answer:
Take a glass trough. Fill it about half with water. Add a few drops of ink to make the water coloured. Fix a candle on a solid iron rectangular block and place the block in water. Take a glass cylinder and mark it into five equal parts by passing a thin strip of paper at equal distance on its outer surface. Light the candle and invert the glass cylinder over it.

The flame of candle starts burning, then becomes and finally stops burning. Coloured water rises up in the glass cylinder and is filled one fifth with water. Thus one fifth of air is used in burning. Hence one fifth volume of air is oxygen.

Question 5.
How will you show that air contains water vapour?
Answer:
Put some ice blocks in a glass tumbler and keep it in the open air. Drops of water appear on the outer surface of glass tumbler after a few minutes. Air in contact with the tumbler gets cooled and the water vapour present in it condenses to give drops of water.

Thus we can see that water is present in air in the form of its vapours.

Question 6.
Explain why air is considered a mixture.
Answer:
Air is considered a mixture because:
(i) The composition of air varies from place to place and at depths and heights.
(ii) The constituents of air such as oxygen, nitrogen, carbon dioxide, water vapours etc. can be separated by simple physical methods.
(iii) The properties of air are the average of its constituents.
(iv) No energy is evolved or absorbed when various components of air (gases) are mixed to obtain air.

Question 7.
Mention five uses of air.
Answer:
Uses of air:
(i) Air is used by humans for respiration.
(ii) Air is necessary for burning.
(iii) Air is used for inflating the tyres of vehicles.
(iv) Balloons and balls can be used only when they are inflated with air.
(v) Compressed air is used in the break system for stopping trains.

Question 8.
How will you show that air is present in a lump of soil?
Answer:
Take a lump of dry soil in a beaker or glass tumbler. Adding water to it, we see that bubbles come out from the soil. This shows that soil contains air.

Question 9.
What will happen if the amount of oxygen in the air is increased?
Answer:
If the amount of oxygen in the air is increased, the burning of thing will not stop and fire will spread into large area which will be dangerous to humans and for the nature.

Question 10.
Why is nitrogen important for living organisms?
Answer:
Nitrogen in air is used for manufacturing food by the nitrogen fixation of atmospheric nitrogen into nitrates which mixes with the soil and plants absorb these as their food. So it is necessary and important for living organisms.

Question 11.
How can we see upto a long distance after it rains?
Answer:
When it rains, the dust in the atmosphere settles down to the ground. This is why we can see upto a long distance just after rain.

Question 12.
How do you know that solid particles are floating in air?
Answer:
Choose a sunny room in your home, now close all the doors and windows to make the room dark. Now open the window/door facing the sun just a little in such a way that it allows sunlight to enter the room only through a slit.

Now look the incoming sunlight slants carefully. We see some tiny shining particles moving rapidly in the slanting beam of sunlight. This shows that air contains dust particles.

Question 13.
Describe the process by which oxygen is naturally produced.
Answer:
Oxygen is naturally produced by the process of photosynthesis. Fill a beaker to about 3/4th with pond water and put a small plant in it. Cover it with a funnel. In this beaker now add a pinch of sodium bicarbonate.

Invert a test tube filled with water on the stem of funnel so that air bubbles get in the test tube.

Now put the apparatus in sunlight and observe after sometime. You will see that some gas has been collected in the test tube. Let half the test tube be collected with this gas. Now remove the test tube by putting thumb at the mouth of the test tube. Bring a splinter in the test tube. Splinters burn rapidly which show that it is oxygen gas.

Question 14.
What is liquid air? How can it be made?
Answer:
When air is cooled under reduced pressure, it is convert into liquid form. This air is called liquid air. Air is cooled under reduced air changes into liquid form.

Question 15.
What would happen if plants stop taking carbon dioxide?
Answer:
Plants prepare their own food with the help of carbon dioxide. They take carbon dioxide from the atmosphere and consume all the carbon dioxide released by animals through the process of respiration.

If plants stop taking carbon dioxide from the atmosphere, the amount of carbon dioxide increases in the atmosphere and the temperature of atmosphere will increase due to green house effect. Due to this, glacier will melt and there will be flooding on the earth. The nature living organisms will die.

Question 16.
Why do divers and mountaineers carry oxygen cylinders with them?
Answer:
Divers and mountaineers carry oxygen cylinders with them because at higher altitude and in oceans, the amount of air/oxygen is very thin. Therefore breathing becomes very difficult.

The divers and mountainears inhale oxygen from these cylinders so that they can breate easily. Therefore, they carry oxygen cylinders with them.

Long Answer Type Questions

Question 1.
Point out different uses of air.
Answer:
Uses of various constituents of air:
1. Uses of Nitrogen:
(i) It helps to slow down the process of combustion.
(ii) It dilutes the concentration of air.
(iii) On a very large scale nitrogen is used for the manufacturer of ammonia, which is used to make fertilizers and nitric acid.
(iv) Due to inertness nitrogen is used to produce a blanketing atmosphere during the processing of food to prevent oxidation which causes food to spoil and affects the natural taste.
(v) Nitrogen is used with argon for filling electric lamps.
(vi) Nitrogen is used for making explosive such as TNT and nitro cellulose.

2. Uses of Oxygen:
(i) Without oxygen, animal life is not possible. It is used for breathing and respiration.
(ii) Mountaineers inhale oxygen at heights, where oxygen is thin, from the cylinders they carry on their backs.
(iii) Fish and other aquatic animals use dissolved oxygen for breathing and respiration.
(iv) It is used in hospitals in many diseases for artificial respiration.
(v) Oxygen with acetylene is used as oxy- acetylene torch as welding and cuttings.
(vi) Liquid oxygen is used as rocket fuels.

3. Uses of Carbon dioxide:
(i) Carbon dioxide is used by plants for making their food.
(ii) Carbon dioxide is used in fire extinguishers.
(iii) It is used in soft drinks such as campa and limca.
(iv) Alcoholic beverages such as bear contains carbon dioxide.

4. Uses of Inert gases:
(i) Inert gas argon is filled in bulbs for the protection of filament of the bulb.
(ii) Helium is used to obtain low temperature.
(iii) Neon is used in special electric bulbs called neon-signs.
(iv) Radon gas is used in the treatment of cancer.

Instead of is used in inflating vehicle tyres, such as cars, scooters and motor-cycles. It is used in compressed form for digging, mining and breaking stones in machines. It is used in drying process for agricultural products such as grains, pulses etc. Air current makes the wind-mill to rotate. Wind-mill is used to draw water from the wells and tube-wells. Air is used for sailing gliders and aircrafts. It also helps in dispersal of seeds.

Air around us Class 6Â  HBSE Notes

• Air is found everywhere. When air is in motion, it is called wind.
• We cannot see air but we can feel it.
• Air occupies space. It is present in water and soil.
• Air is a mixture of oxygen, nitrogen, carbon dioxide, argon and few other gases, water vapours and dust particles.
• Oxygen is necessary for burning and breathing.
• The cover of air surrounding the earth is known as atmosphere.
• Atmosphere is essential for the life on the earth.
• Aquatic animals use dissolved oxygen/air in water for respiration.
• Plants use carbon dioxide to produce their food and release oxygen.
• The plants and animals are inter dependent for gaseous exchange.
• Air is useful in many ways. It is used for inflating tyres, balloons, and for winnowing.
• Air is also used in several musical instruments.
• Without oxygen, animal life is not possible. Mountaineers inhale oxygen at height, where air is thin from the cyclinders of oxygen.
• Oxygen is a supporter of combustion. Ice presence increases the burning process.
• Plants and animals exchange air and are interdependent on each other.