Class 6 Chapter 15 Science Air Around Us Extra Questions

A lump of cotton wool has a lot of air trapped inside the space present in its fibers. When this lump of cotton is immersed in water, all the air is replaced by water. Because of this, the cotton lump shrinks in water.

Chimneys take harmful gases and smoke of the factories away and prevent it from entering our nose.

When an empty glass bottle is inverted into a bottle of water vertically, water does not enter the bottle because the bottle contains air. The bottle is already filled with air and hence water does not enter inside it.

yes, when water is heated the air dissolved in it comes out in the form of tiny bubbles.

When it rains heavily, water fills up all the spaces occupied by the air in the soil. So, the     organisms living in soil has to come out for respiration.

The organism is earthworm.
They respire by taking oxygen present in the soil. Also make deep burrows and holes in the soil through which the air reaches them for respiration.

i. oxygen is necessary for burning.
ii. when the burning candle is covered with a gas jar then the fresh supply of air to the candle is cut off and hence it stops burning.

i. A windmill being used to run a pump to draw water from the ground.
ii. Air rotates the wind mill blades continuously. When the blades rotate the crank attached to the blades also rotate. When the crank rotates then its U-bend lifts pump rod up and down continuously. The rod works the pump which lifts the water from ground.

1. Dusting at home, traffic on the roads, construction activities.
2. Nose have fine hair and mucus to prevent dust particles from entering into our respiratory system. If we breathe through our mouth then the dust particles will enter the respiratory tract.

1. Water cycle
2. Hot air being lighter rises up and carries water vapour high up in the sky and helps in bringing rain.

Air is a matter and is attracted towards earth due to gravity. Because of this reason air density is more at earth's surface but decreases as we go up and hence air becomes thinner as we go at higher altitudes.

Carbon dioxide is an important raw material for photosynthesis by which the plant makes food.

If the percentage of oxygen in the air reaches to around 78% then, if any substance catches fire it will become difficult to extinguish the fire, because oxygen supports combustion.

The plants leave carbon dioxide at night. On the basis of this it is that in the night if you sleep under the tree, you will not get oxygen, but get carbon dioxide which can be suffocating.

1. Carbon dioxide
2. 0.03%
3. This gas serves as a raw material for photosynthesis which provides food for the plant and for all other animals.

mercury. Hydrogen and helium are present.