Science [5 Marks Each] QUE-ANS

Carbon dioxide has the property of absorbing heat rays called infrared rays. Nature has a balance of carbon dioxide in the atmosphere, thus giving an optimum warmth to the atmosphere. The increase in the concentration of carbon dioxide in the air would cause increase in the temperature of the earth and would ultimately lead to melting of glaciers causing floods etc. This phenomenon is called global warming.

We inhale air when we breathe through our nostrils. We also know that air contains dust particles. To prevent dust particles from getting into the respiratory system, fine hair and mucus are present inside the nose. Since, our mouth does not contain the above discussed barriers of dust, so if we breathe through it, dust particles may enter in our respiratory tract. That is why breathing through mouth is not suggested.

We inhale air when we breathe through our nostrils. We also know that air contains dust particles. To prevent dust particles from getting into the respiratory system, fine hair and mucus are present inside the nose. Since our mouth does not contain the above-discussed barriers of dust, so if we breathe through it, dust particles may enter in our respiratory tract. This is why breathing through mouth is not suggested.

The air is present in spaces between particles of soil. Animal living inside the soil get oxygen for breathing (or respiration) from the air present between the soil particles. However, when it rains heavily water fills up the spaces occupied by the air in the soil. In this situation, the animals living inside the soil have to come out of the soil to obtain air for breathing. For example, the earthworms come out of the soil only during heavy rains.

When air comes in contact with a cool surface, it condenses and forms tiny drops of water on the cooled surfaces. The presence of water vapour in the air is important for maintaining the water cycle in nature. This is because it is water vapour present in the air which rises high in the sky along with hot air, get cooled, condenses to form clouds and then brings rain on the earth.