Air Around Us

Air is present everywhere. The organisms which live in the soil need oxygen(air) to breath so between the soil particles some amount of air is present.

Wind help in the movement of firki, weather cock and sailing yacht but it does not play any role in the movement of ceiling fan. Fan rotate with the help of electricity.

Air play an important role in water cycle. It helps the water vapour to rise up and also help in the formation of cloud.

When we go higher and higher the oxygen and pressure decreases. At higher altitude the amount of oxygen decreases and it become difficult to breath so the mountaineers carry oxygen cylinders with them.

When the bottle was tilted then the bubbles of air come out from the bottle and some amount of water entered the bottle.

The air is the mixture nitrogen, oxygen, carbon dioxide, water vapour and smoke. Nitrogen is the component of air which is present in the largest amount in the atmosphere. It occupies 78% of the atmosphere.

Smoke contains few gases and fine dust particles which is harmful. Dust and smoke cause the respiratory diseases.

Usha observed bubbles coming out from the soil as between the soil particles some amount of air is present.

(a) True

Plant contains the stomata. Stomata are minute pores present on epidermics of leave and are meant for gaseous exchange (respiratory gasses) and transpiration. Oxygen and carbon dioxide enters into the plant through the stomata and are used in respiration and photosythesis.

(b) True

The amount of oxygen produced by the plant during photosynthesis is more than the amount of oxygen consume by the plant during respiration. Plant produce oxygen during photosynthesis and consume oxygen during respiration. Plant take the carbon dioxide through the leaves(stomata) and combined it with water and sunlight to form their food(glucose). During this process oxygen is also formed as a byproduct. Which is relased into the atmosphere.

(c) False

Air helps in the movements of sailing yachts and glider as well as it (air) also play an important role in the flight of birds and aeroplanes.

(d) False

Air occupies every space that is available to it. Air is everywhere.

Air plays an important role in a number of musical instruments such as—

i. Harmonium

ii. Shahnai

iii. Trumpet

iv. Flute

v. Air violin

a) Windmill

b) Oxygen

c) Smoke

d) Dust

(a) Oxygen and Nitrogen together make 99% of air.

(b) Aquatic animals used dissolved air for respiration.

(c) Air in motion is called wind.

Or

Motion air is called wind.

(a) Wind

(b) Mixture

(c) Direction

(d) Cylinders

(a) Mask is covering the nose and mouth of the police man.

(b) He is putting a cover(mask) on his nose so that he do not inhale the dust particles and harmful gases which are produce by the moving vehicles (automobiles) as harmful gases make it difficult to breath and may cause lung diseases like asthma.

(c) The quality of the air is Bad. The harmful gases released by the vehicles spread and contaminate the air. Thus making the quality of air bad.

When Garima left her tightly capped bottle full of water in the open sunlight then air dissolved in the water start escaping in the form of tiny bubbles because of the heat energy given by sun.

(a) Firki rotates when the force is applied to the blades of the first. The force is applied on the blades of the first by the moving air called wind but in the closed area there is lack of air movement (wind) so firki does not rotate in a closed area.

(b) The arrow of weather cock points towards a particular direction because it tells us about the current direction of the wind(air) at that time.

Or

The arrow of weather cock points towards a particular direction because it tells us about the direction of wind movement.

(c) We can say that an empty glass, in fact, is not empty as it is filled with the air. We cannot see the air but we can feel it as air is transparent and has no weight. Air do not have a fixed shape and fixed volume.

(d) It is right to say that breathing through the mouth may harm us because the air contains dust particles and if we breathe through mouth then the harmful dust particles may enter our body(respiratory system) and cause damage to lungs. But If we breathe through the nostrils then the fine hair and mucus which is present in the nose may prevent the dust particles from entering our body.

(a) If oxygen disappear from the atmosphere then—

i. There will be no life on the earth.

ii. Burning will be not possible due to disappear of oxygen.

iii. Plants and animals consume oxygen for respiration. If there is no oxygen then there will be no plant and animal life.

(b) Nitrogen does not support burning. No nitrogen means that things will burn fast. If there is no nitrogen humans will be dehydrated quickly. The flow of nitrogen cycle will also disturb and the growth of plants will decrease, even cause the death of plants.

(c) Animals produce carbon dioxide. Carbon dioxide is needed by the plants for photosynthesis. If there is no carbon dioxide then plants are not able to make their food due to which there will be no plants and animals as animal depends upon the plants for food.

(a) Tiny bubbles were formed/appeared because the air dissolved in the water start escaping in the form of tiny bubbles on boiling.

(b) No, there will be no tiny bubbles because there is no dissolved air left in the water.

The leaves and flowers of the roadside plants were comparatively very dull because the air quality near the roadside is very bad due to the emission of harmful gases and dust particles from automobiles. These dust particles get stuck with the plants and make them appear dull.