Air – The Envelope of life

 Air – The Envelope of life

:

Ø What happens when you fan yourselves/sway the paper fans near your

face?

Our hair moves, feel air, cool breeze etc. on our face.

Ø Why does your hair move or you feel the cool breeze on your face?

         Because of air.

          Ø Can you see air?

            (No)

         Ø Give some examples in our daily life where we can feel the presence of air

around us.

Moving of leaves on trees, swaying of clothes, fluttering of pages

of our books/ newspaper when fan is switched on, flying of kite, breathing

etc..

:

Ø While breathing what is it that we take in and give out?

Air rich in oxygen is taken in and air rich in carbon dioxide is given out

Ø Is breathing essential to our survival?

Yes

Ø Will we survive without air?

No,air is one of the most important components required for the survival of living organisms. We can live without food and water for few days but not without air.

Ø If I give you a football that is filled with air and a football without any air,

which football out of the two do you think will have more weight? Why?

The foot ball filled with air, because it has air in it.

Ø Are both the balloons in same line/ the ruler is straight in line?

 (yes)

· Now, pierce one of the balloons with the pin:

Ø Are both the balloons in same line/ the ruler is straight in line?

 (No)

Ø Which side of the ruler has gone up? Why?

The side of the punctured/ pierced balloon because this side has become lighter.

:

Ø Which side of the ruler feels heavier/ has more weight?

the side which has the balloon still filled with air.

·  when the balloons filled with air were hung on the ruler, they

weighed the same. But when one of the balloons was punctured, then the other

side of the ruler stooped down.

This proves that air has weight.

® We can live without food and water for few days but we cannot live Without air.

® We cannot see air but we can  feel it.

® Air has _weight

airir occupies space.

Ø What are the properties of air?

air is present all around us,

 air occupies space,

 air has weight.

Ø Why is air important to us?

(air is an important component required for our survival, we breathe air etc)

Ø Is air present inside the class room, outside the class room, in the playground,

on the street?

Yes, air is present everywhere.

® The atmosphere extends to a height of about 300 kilometres above the

Earth's surface.

® As we go high up in the atmosphere, the amount of air becomes lesser.

:

Ø What is air made up of?

Gases, oxygen, nitrogen, duct particles etc.

Ø Name the gases that are found in the air.

Oxygen, nitrogen, carbon dioxide,water vapour.

Ø How is oxygen essential to human beings and plants?

Oxygen is essential for/breathing in human beings and for process of respiration in plants.

Ø How do fish and some aquatic animals breathe in water?

Dissolve oxygen, air in water.

:

Ø Do you see tiny bubbles as the vessel is slowly heated?

 (yes)

Ø What may happen if the process of heating the water in the vessel is

Continued

The water will be converted to steam or water vapour.

Ø Give examples of certain animals that live in soil.

Earthworms, ants, bugs,rats, snake, termites etc.

Ø Where do these animals get their supply of oxygen in order to survive?

From the air present in the soil, they come up to the surface of the soil to breathe.

:

Ø Which is the most essential gas for breathing and survival of all living

organisms on the Earth?

Oxygen

Ø What is the percentage of oxygen present in the air?

21%

Ø Aquatic animals breathe in air in which form, in the water?

Dissolved form of air, in the water.

Ø What happens in water cycle?

Water is recycled in the environment, water moves from the sky to the ground and back in the water cycle.

Ø What is oxygen cycle?

Oxygen gas is cycled through the environment.

:

Ø What happens during the process of photosynthesis?

Plants take in carbondioxide and convert it and water into carbohydrate and give out oxygen.

Ø What happens during the process of respiration? (Human beings and animals

breathe in oxygen which they use to break carbohydrates down into energy

 Define the oxygen cycle.

The cycle in nature, in which oxygen is consumed for respiration and is released during the process

of photosynthesis is called oxygen cycle.

Ø What will happen to the balance of oxygen if we cut down trees excessively?

Balance of oxygen will be disturbed, the amount of oxygen in air will fall. oxygen is vital for the

 survival of all the living organisms whether they live on land, in water or in soil. Although oxygen is

being continuously used by all living forms, its percentage is constant in atmosphere due to the process of photosynthesis carried out by plants. Thus,we should plant more trees so that the

supply of oxygen in the atmosphere is well balanced.

Ø Is it possible to burn anything without oxygen? Why?

No, because oxygen is necessary for burning.

® Burning requires air relatively rich in oxygen. The candle does not

come close to using up all the oxygen in the jar.

.

® Carbon dioxide forms a blanket around the flame of a tall candle,

cutting off the air supply, due to which the flame gets extinguished.

® This is one reason why we are told to crawl if we are in a burning

building: the oxygen-rich air is near the floor.

:

Ø Name the process in which plants take up carbon dioxide and release

Oxygen

Photosynthesis

Ø Name the process in which animals take up oxygen to break down

carbohydrate and release carbon dioxide.

Respiration

Ø Explain why net oxygen is sufficient to support and sustain all forms of life?

Since the oxygen released during photosynthesis is much more than the

oxygen consumed in respiration, the net oxygen is sufficient to support and

sustain all forms of life.

:

Ø Why is presence of oxygen on Saturn’s moon an important discovery?

Oxygen support life, so presence of oxygen on Saturn’s moon may indicate

extraterrestrial life/ alien life,

 Ø Name the other gases that are present in the air apart from oxygen.

Nitrogen, carbon dioxide and water vapour.

 Ø What is the percentage of carbon dioxide in the air?

0.03%

Explain that the atmosphere contains 0.03% of carbon dioxide.

Carbon dioxide is yet another important component of air, which is used by the plants to

 synthesise food.

:

Ø What happens to the water in a jar if we heat it for a long time?

The water in the jar will boil and turn in steam, water vapour, vaporize.

Ø Is water vapour present in the air too? (yes)

Ø What do you observe on the outer side of the beaker?

Tiny droplets of water.

® Air has water vapour. When water vapour comes in contact with a cold

surface, the water vapour condenses to form water.

® Water vapour is also formed due to evaporation and heating of water. This is

also important for the process of water cycle in nature.

.

.

Ø What do you understand by fresh air?

Clean, healthy, free of dust etc.

Ø Which air is healthy for us; clean fresh air or dirty air full of smoke and dust?

Clean fresh air

:

Ø What do you understand by the term ‘pollution’?

Release of substances that are harmful to the environment as well as human health, other living

organisms, cause damage, contamination of resources, etc.