Class 6 - Chemistry - Air Around us
What is the composition of air?
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.
Which gas in the atmosphere is essential for respiration?
Oxygen gas in the atmosphere is essential for respiration.
How will you prove that air supports burning?
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.
How will you show that air is dissolved in water?
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.
Why does a lump of cotton wool shrink in water?
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.
The layer of air around the earth is known as ___________.
The layer of air around the earth is known as atmosphere.
The component of air used by green plants to make their food is ___________.
The component of air used by green plants to make their food, is carbon dioxide.
List five activities that are possible due to the presence of air.
Activities due to presence of air:
(ii) Formation of clouds
(vi) Flying of birds
How do plants and animals help each other in the exchange of gases in the atmosphere?
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.