Class 06 || Science || Ch. 15. Air around Us

Class 06 || Science || Ch. 15. Air around Us

Q.1 What is air? 

Ans. Air is flud which is found everywhere. We cannot see air but we can feel it. Air is a mixture of nitrogen, Oxygen, carbon dioxide, water vapour and other gases. Some dust particles may also be present in it.

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.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 for release of 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 producers 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.

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. Look carefully at the inner surface of the vessel,

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:

(i) Winnowing

(ii) Formation of clouds

(iii) Respiration

(iv) Photosynthesis

(v) Transpiration

(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.