Composition of Air Class 4 SCIENCE - Orchids
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Composition of Air for Class 4 Science

  • Air is a mixture of gases, the envelope of air that surrounds the earth is known as the atmosphere.
  • It is a mixture of nitrogen, oxygen, carbon dioxide.
  • Apart from these gases water vapour is also present in the air.
  • The inert gases in air are the types of non-reactive gases.
  • The composition of air on Earth is appropriate to support life on this earth.
  • The combustion of a substance takes place only in the presence of air.
  • The pressure exerted by air is called air pressure, which decreases with an increase in altitude.

Properties of Air and its Composition

Question 1:

How Do Helium Balloons Float?

Answers:

  • Helium is a gas that is less dense than air.
  • When a balloon is filled with helium gas, it floats in the air displacing the air molecules.
gas-balloon

Question 2:

What Are Inert Gases?

Answers:

  • The gases that do not react with anything under a given set of conditions are called inert gases.
  • Examples of inert gases are helium, neon, xenon, and argon.
  • These gases are used in chemical factories to reduce the chances of chemical hazards caused by highly reactive substances.

Question 3:

Write Some Uses of Carbon Dioxide.

Answers:

  • Carbon dioxide is used as a fire extinguisher.
  • Carbonated beverages have carbon dioxide gas.
  • Plants use it during photosynthesis.
  • It is necessary for the greenhouse effect, which is essential to maintain the earth's temperature.
fire-extinguisher

Question 4:

Why Are Freshly Fallen Meteorites Too Hot To Touch?

Answers:

  • Meteorites are celestial bodies that fall on the earth’s surface during a meteor shower.
  • When meteorites travel through the atmosphere, a frictional force is exerted by air.
  • Most meteorites burn entirely due to the heat generated by the frictional force of the air.
  • Therefore, the meteorites that reach the earth’s surface remain very hot.
meteor-shower

Question 5:

How Will You Prove by an Activity That Air Exerts Pressure?

Answers:

The following activity proves that air exerts pressure—

  • Take a hard-boiled egg and remove its shell.
  • Light a matchstick and put it carefully into an empty glass bottle.
  • Put the peeled egg in the bottle’s mouth, keeping the narrower end of the egg towards the mouth of the bottle.
  • After a few minutes, the egg will drop into the empty glass bottle.
  • It happens because the flame of the lit match consumes all the air in the bottle, which creates low air pressure. As the air pressure outside is higher, the egg is pushed inside the bottle.
experiment-on-air-pressure-with-boiled-egg

Question 6:

What Is Altitude Sickness?

Answers:

  • The uneasiness felt while travelling in mountain areas is called altitude sickness.
  • It happens due to reduced oxygen concentration in the air as we move upwards to greater heights.
  • As a result, an individual's breathing rate increases, which may sometimes lead to nausea and nose bleeding.
  • So, mountaineers carry oxygen cylinders during expeditions.
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What is Combustion and Breathing?

Question 1:

How Does Coronavirus Affect Our Lungs?

Answers:

  • Our lungs are made up of tiny air sacs called alveoli.
  • Coronavirus enters our body through respiratory tubes. As a result, the air sacs get filled with mucus, fluid, and debris.
  • Due to such a situation, the air sacs cannot exchange gases while breathing.

Question 2:

Why Do Walls of the Trachea or Windpipe Not Collapse When There Is Less Air?

Answers:

The windpipe has numerous C-shaped rings made of cartilage that maintain the shape of the trachea.

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Question 3:

Why Is Our Left Lung Smaller Than the Right One?

Answers:

  • Our left lung is smaller than the right one because it has two lobes, whereas the right has three lobes.
  • It is an adaptation of the body to accommodate the heart in the thoracic cavity.
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Question 4:

Why Is the Right Lung More Susceptible to Infections?

Answers:

  • The right lung is more susceptible to infections because the right main bronchiole is wider than the left.
  • This bronchiole is vertically connected with the tracheal tubes of the right lung.
  • Due to this, air, as well as airborne germs, can quickly enter the alveoli of the right lung.
  • If food accidentally enters the respiratory tube, it easily moves into the right tracheal tubes.

Question 5:

Why Does a Burning Candle Extinguish When Covered With Glass?

Answers:

  • Burning, also known as combustion, needs air and especially oxygen.
  • A burning candle covered with glass burns for a few seconds and then extinguishes. It happens because the oxygen supply is interrupted as soon as the candle is covered.
  • Without the presence of oxygen, the candle stops burning.
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