Class 6 || Science || Ch. 15. Air around Us

Class 6 || Science || Ch. 15. Air around Us

Q.1 What is air? 

Ans. Air is colourless and transparent flud which is present everywhere around us. We cannot see air but we can feel it. Air occupies space, can fills all the space. 

Actually air is a mixture of nitrogen, Oxygen, carbon dioxide, water vapour and other gases with some dust particles.

Q.2 What is air made up of?

Ans. Air is mixture of nitrogen, Oxygen, carbon dioxide, water vapour, dust particles and some other gases etc.

Q. What is weather cock and what is its use?

Ans. Weather cock shows the direction in which the air is moving at that place.

Q.3 What is atmosphere? 

Ans. The thin layer of air surrounding the earth and extends too many kilometres above the surface of the earth is called atmosphere?

Q.4 Why did mountaineers carry oxygen cylinder with while climbing high on mountains? 

Ans. As we move higher in the atmosphere the air gets rarer. The level of the oxygen also decreases to fulfill the oxygen the mountaineers carry oxygen cylinder with them while climbing high mountains.

Q.5 What is water vapour? 

Ans. Evaporated water present in atmosphere is called water vapours when air comes in the contact with the cool surface, it condenses in the form of water.

Q.6 What is oxygen? 

Ans. Oxygen is a gas which is present in 20% in atmosphere which helps in burning and in respiration. In respiration it release the energy from food.

Q.7 What is nitrogen? 

Ans. Nitrogen is a gas which is 79% in atmosphere which is nearly four-fifth of the space in air. It does not support in burning and respiration.

Q.8 What is carbon dioxide? 

Ans. It is a gas any burning organic material produce carbon dioxide.

Q.9 What is smoke? 

Ans. On burning of fuel some gases and dust particles produces this combined form is called smoke it is often harmful for everybody.

Long chimneys in factories takes the harmful smoke and gases away from our nose but it brings it closer to the birds flying up in the sky and is harmful for them.

Q. How the bubbles produced in boiling water?

Ans. We know that the air dissolved in the water. When we start to boil the water, we see tiny bubbles coming out from it. 

At first water turns into vapour and finally in bubbles when it begins to boil. 

Actually these bubbles come from the air dissolved in water. When we heat the water, the air dissolved in it escapes in the form of bubbles. 

Q. From where the aquatic animals take oxygen?

Ans. The animals living in water use the dissolved oxygen in water.

Q. The organisms that live in soil also need oxygen to respire, isn’t it? 

Ans. The air is also presence in the soil. The organisms that live inside the soil use the oxygen of air presence in the soil. The plant roots also respire in this air. 

Q. Why did the organism in soil came out after the heavy rain?

Ans. The animals living in the soil's burrows and holes formed in deep soil. These spaces of burrows and holes is occupied by air. 

After heavy rain, water fills up all the spaces occupied by the air in the soil. 

In this situation, animals living in the soil have to come out for respiration. This is the reason that the earthworms come out of the soil during heavy rain.

Q.  Plants also consume oxygen for respiration, Why we say plants

produce oxygen? 

Ans. In photosynthesis, plants

make their own food and oxygen is

produced along with it. 

Plants also consume oxygen for respiration, but they produce more of it than they consume. That is why we say plants produce oxygen.

Q. Is it true that plants can not survive for long without animals? 

Ans. Yes, it is true that plants can not survive for long without animals. in absence of the animals the plants  would consume all the carbon dioxide in the atmosphere. 

We can say that both need each other, for balancing or maintaining of oxygen and carbon dioxide in the atmosphere. This shows that the plants and animals interdependence relationship.

Q. What is Windmill and what is its use? 

Ans. Windmill is device for tapping the energy of the wind by means of sails mounted on a rotating shaft. 

The wind makes the windmill rotate. The windmill is used to draw water from tubewells and to run flour mills. Windmills are also used to generate electricity. 

Q. What are main works performed from the air?

Ans. Air helps in the movements of sailing yachts, gliders, parachutes and aeroplanes. Birds, bats and insects can fly due to the presence of air. Air also helps in the dispersal of seeds and pollen of flowers of several plants. Air plays an important role in water cycle.

Some other are:

(i) Winnowing

(ii) Formation of clouds

(iii) Respiration

(iv) Photosynthesis

(v) Transpiration

(vi) Flying of birds

Exercise

Q. 1 What is the composition of air?

Ans. Air contains some gases, water vapour and dust particles. The gases in air include nitrogen, oxygen, small amount of carbon dioxide and many other gases.

The gases that make up maximum proportion are nitrogen (78%) and oxygen (21%).

Remaining 1% us constituted by carbon dioxide and few other gases, water vapour and dust particles.

Q. 2 Which gas in the atmosphere is essential for respiration?

Ans. Oxygen gas in the atmosphere is essential for respiration.

Q. 3 How will you prove that air supports burning?

Ans. Two lighted candles are taken. One candle is fixed in a tumbler containing water.

This candle is covered by an inverted glass. After sometime, the covered candle gets extinguished and water rises up to 1/5th in one of the glass.

This shows that oxygen is necessary for burning because 1/5th is oxygen. The candle was extinguished as soon as all the oxygen was used up.

Q. 4 How will you show that air is dissolved in water?

Ans. Take some water in a glass vessel or beaker. Heat it slowly on a tripod stand. Before reaching to its boiling point, the bubble of air start rising from bottom to surface. These bubbles come from the air dissolved in water.

Q. 5 Why does a lump of cotton wool shrink in water?

Ans. A lump of cotton wool shrinks in water because the air inside wool cotton is driven out by water.

The layers stick together and hence lump shrinks.

Q. 6  The layer of air around the earth is known as ___________.

Ans. atmosphere.

Q. 7 The component of air used by green plants to make their food is ___________.

Ans. carbon dioxide.

Q. 8 List five activities that are possible due to the presence of air.

Ans. Activities due to presence of air:

Air helps in the movements of sailing yachts, gliders, parachutes and aeroplanes. Birds, bats and insects can fly due to the presence of air. Air also helps in the dispersal of seeds and pollen of flowers of several plants. Air plays an important role in water cycle.

Some other are:

(i) Respiration 

(ii) Photosynthesis 

(iii) Transpiration

(iv) Formation of clouds

(v) Winnowing 

(vi) Flying of birds

Q. 9 How do plants and animals help each other in the exchange of gases in the atmosphere?

Ans. There is the interdependence of plants and animals. Plants and animals respire i.e. they intake oxygen and gives out carbon dioxide in the atmosphere.

Plants take carbon dioxide from the atmosphere and prepare food and return oxygen to atmosphere by the process of photosynthesis.

So, in this way plants and animals help each other in the exchange of gases in the atmosphere.