# NCERT Exemplar Class 6 Science Chapter 15 Air Around Us

In this chapter, we provide NCERT Exemplar Problems Solutions for Class 6 Science Chapter 15 Air Around Us for English medium students, Which will very helpful for every student in their exams. Students can download the latest NCERT Exemplar Problems Solutions for Class 6 Science Chapter 15 Air Around Us pdf, free NCERT Exemplar Problems Solutions for Class 6 Science Chapter 15 Air Around Us book pdf download. Now you will get step by step solution to each question.

## NCERT Exemplar Class 6 Science Solutions Chapter 15 Air Around Us

Multiple Choice Questions

Question 1.
Which of the following statements is incorrect?
(a) All living things require air to breathe.
(b) We can feel air but we cannot see it.
(c) Moving air makes it possible to fly a kite.
(d) Air is present everywhere but not in soil.
Solution:
(d): Air is omnipresent and is present in the soil also. This can be proved by a simple activity where a lump of dry soil is taken in a beaker or a glass. When water is added to the soil, it displaces the air which is seen in the form of bubbles.

Question 2.
Wind does not help in the movement of which of the following?
(a) Firki
(b) Weathercock
(c) Ceiling fan
(d) Sailing yacht
Solution:
(c): Ceiling fan moves by electricity, and hence, wind does not help in the movement of ceiling fan.

Question 3.
What is not true about air?
(a) It makes the windmill rotate.
(b) It helps in the movements of aeroplanes.
(c) Birds can fly due to presence of air.
(d) It has no role in water cycle.
Solution:
(d) : Air plays a major role in water cycle. Air helps the water vapour to rise up to form clouds. Evaporation of water, cloud formation and falling of rain, all take place in the atmosphere.

Question 4.
Mountaineers carry oxygen cylinders with them because
(a) there is no oxygen on high mountains
(b) there is deficiency of oxygen on mountains at high altitude
(c) oxygen is used for cooking
(d) oxygen keeps them warm at low temperature.
Solution:
(b): With increase in altitude, the atmosphere gets thinner and the supply of oxygen is reduced. This causes difficulty in breathing on hill stations and mountains. Therefore, while climbing high mountains, mountaineers carry oxygen cylinders with them.

Question 5.
Boojho took an empty plastic bottle, turned it upside down and dipped its open mouth into a bucket filled with water. He then tilted the bottle slightly and made the following observations.
(i) Bubbles of air came out from the bottle.
(ii) Some water entered the bottle.
(iii) Nitrogen gas came out in the form of bubbles and oxygen got dissolved in water.
(iv) No bubbles formed, only water entered the bottle.
Which observations is / are correct?
(a) (i) and (ii)
(b) (iv) only
(c) (iii) and (iv)
(d) (i) only
Solution:
(a)

Question 6.
Which of the following components of air is present in the largest amount in the atmosphere?
(a) Nitrogen
(b) Oxygen
(c) Water vapour
(d) Carbon dioxide
Solution:
(a) Atmosphere cpntains 78% nitrogen, 21% oxygen and remaining 1% is formed by carbon dioxide, water vapour, few other gases and dust particles. Thus, atmosphere contains nitrogen in the largest amount.

Question 7.
The components of air which are harmful to living beings are
(a) nitrogen and carbon dioxide
(b) dust and water vapour
(c) dust and smoke
(d) smoke and water vapour.
Solution:
(c) Water vapour, nitrogen and carbon dioxide are useful to living beings. Water vapour is important for the water cycle in nature. Nitrogenisnecessaryforplants. Carbon dioxide is essential for photosynthesis.

Question 8.
Ushatooka lump of dry soil in a glass and added water to it till it was completely immersed. She observed bubbles coming out. The bubbles contain
(a) water vapour
(b) only oxygen gas
(c) air
(d) none of these.
Solution:
(c) When the water is poured on the lump of soil, it displaces the air trapped in it which is seen in the form of bubbles.

Question 9.
State whether the following statements are true or false. If false, correct them.
(a) Plants consume oxygen for respiration.
(b) Plants produce oxygen during the process of making their own food.
(c) Air helps in the movements of sailing yachts and gliders but plays no role in the flight of birds and aeroplanes.
(d) Air does not occupy any space.
Solution:
(a) True
(b) True
(c) False – Air helps in the movement of sailing yachts and gliders and also helps in the flight of birds and aeroplanes.
(d) False – Air does occupies space.

Question 10.
In a number of musical instruments, air plays an important role. Can you name such instruments?
Solution:
Air plays an important role in a number of musical instruments such as flute, trumpet, mouth organ, shehnai and harmonium.

Question 11:
In the boxes of Column I, the letters of some words got jumbled. Arrange them in proper form in the boxes given in Column II.

Solution:
(a) Windmill (b) Oxygen
(c) Smoke (d) Dust

Question 12.
Make sentences using the given set of words.
(a) 99%, oxygen, nitrogen, air, together
(b) Respiration, dissolved, animals, air aquatic
(c) Air, wind, motion, called
Solution:
(a) Oxygen and nitrogen together make up 99% of the air.
(b) Aquatic animals use dissolved air for respiration.
(c) Air in motion is called wind.

Question 13.
A list of words is given in a box. Use appropriate words to fill up the blanks in the following statements.
[Air, oxygen, wind, water vapour, mixture, combination, direction, road, bottles, cylinders]
(a) The ______ makes the windmill rotate.
(b) Air is a ______ of some gases.
(c) A weather cock shows the in which the air is moving at that place.
(d) Mountaineers carry oxygen ___ with them, while climbing high mountains.
Solution:
(a) wind
(b) mixture
(c) direction
(d) cylinders

Question 14:
Observe the given figure carefully and answer the following questions:

(a) What is covering the nose and mouth of the policeman?
(b) Why is he putting a cover on his nose?
(c) Can you comment on air quality of the place as shown in the figure?
Solution:
(a) Mask is covering the nose and mouth of the policeman.
(b) Policeman is putting a cover on his nose to save himself from dirt/polluted air.
(c) Air quality of the place is not good. It is due to the smoke and gases emitted by the automobiles along with dust particles present in the air.

Question 15.
Garima observed that when she left her tightly capped bottle full of water in open sunlight, tiny bubbles were formed all around inside the bottle. Help Garima to know why it happened?
Solution:
Air dissolved in water starts escaping in the form of tiny bubbles due to heat from the sun. Thus, tiny bubbles were formed all around inside the bottle.

Question 16.
Match the items of column I with the items of column II.

Solution:
(a) – (iv)
(b) – (iii)
(c) – (v)
(d) – (i)
(e) – (ii)

Question 17.
Explain the following observations very briefly.
(a) A firki does not rotate in a closed area.
(b) The arrow of weather cock points towards a particular direction at a particular moment.
(c) An empty glass in fact is not empty.
(d) Breathing through mouth may harm you.
Solution:
(a) A firki or pmwheel rotates when placed in an open area due to the moving air present all around. In a closed area, there is a lack of air movement which does not support the rotation of a firki.
(b) A weather cock is an instrument used for indicating the direction of the wind. It consists of an arrow, mounted at its centre of gravity so it can move freely about a vertical axis. Therefore, the arrow points towards a particular direction at a particular moment to show the latest direction of the wind movement.
(c) An empty glass is filled with the air. ft is filled completely with air even if turned upside down. It can be proved with a simple experiment in which an empty bottle is turned upside down in a beaker filled with water. The water does not enter the bottle when it is pushed’in an inverted position because there is no space for air to escape. When the bottle is tilted, the air is able to escape out in the form of bubbles and water fills up the empty space. This shows that even an empty glass is filled with the air.
(d) Air contains some gases, water vapour and dust particles. When air is inhaled through nostrils, the fine hair and mucus present in the nose prevent dust particles from entering the respiratory tract. But, if we breathe through mouth, the harmful dust particles may enter our body and make us ill. Thus, breathing through mouth may harm us.

Question 18.
Write just a few sentences for an imaginary situation if any of the following gases disappear from the atmosphere.
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
Solution:
(a) If oxygen gas disappeared from the atmosphere, life would not be possible on earth as the presence of oxygen is essential for the survival of the living organisms. Animals and plants take in oxygen from the atmosphere and release carbon dioxide during respiration. Even the aquatic plants and animals take up oxygen in the dissolved form for breathing. It would not be possible for organisms to breathe in the absence of oxygen and hence, eventually the organisms will die.
(b) Nitrogen constitutes major part i.e. 78% of the atmosphere and it does not support burning. If nitrogen gas disappeared from the atmosphere, things on earth will bum very fast which may produce disastrous results. Moreover, nitrogen is required by plants for their growth, although plants are not able to absorb the nitrogen directly from the air. They ocnsume it in the soluble form either through fertilisers or by converting it into nitrate compounds which are absorbed by the plants through soil. Nitrogen is also present in some amounts in all the proteins. All living things need protein for their growth. Thus, if nitrogen gets disappeared from the atmosphere, plants, animals, humans and other organisms would not be able to grow properly and may eventually die.
(c) Although carbon dioxide is present in traces (0.03%) in the atmosphere, it plays a major role in the survival of living beings. Plants require carbon dioxide to manufacture their own food by the process of photosynthesis. During this process, oxygen in evolved out. This maintains the carbon dioxide oxygen balance in the air. If carbon dioxide gets disappeared from the atmosphere, the plants will not be able to produce their food and oxygen will not be released which will disturb the carbon dioxide – oxygen ratio in the atmosphere. In the absence of oxygen and food, there will be no life on earth.

Question 19.
Paheli kept some water in a beaker for heating. She observed that tiny bubbles appeared before the water started to boil. She boiled the water for about 5 minutes and filled it in a bottle up to the brim and kept the bottle air tight till it cooled down to room temperature.
(a) Why did the tiny bubbles appeared?
(b) Do you think tiny bubbles will appear on heating the water taken out from the bottle? Justify your answer.
Solution:
(a) The tiny bubbles appeared before the water started to boil due to the air dissolved in water. On heating, the air dissolved in water escaped in the form of bubbles.
(b) The tiny bubbles will appear on heating the water taken out from the bottle as on opening the cap, some amount of air will be trapped in it. Some amount of air will also be trapped during the transfer of water from the bottle to the utensil for heating. Since the amount of trapped air will be less in the poured water, there will be less number of bubbles appearing in the water on heating as compared to the previous one.

Question 20.
On a Sunday morning Paheli’s friend visited her home. She wanted to see some flowering plants in the nearby garden. Both of them went to the garden. While returning from the garden they also observed some flowering plants on the road side. But to their surprise they found that the leaves and flowers of these roadside plants were comparatively very dull. Can you help them to know why?
Solution:
The dull appearance of the leaves and flowers of the roadside plants may be due to the djust and soot particles emitted from the vehicles, chimneys and factories. These particles might have got deposited on the plant parts which made them appear dull.

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