Class 6 Science Chapter 11 MCQ

During heavy rains, all the spaces in soil which contained air get filled by rain water leaving no air in the soil for the earthworms to breathe in. Due to this, the earthworms have to come out of the soil to obtain air for breathing or respiration.

As we know that oxygen gas does not burn itself but it allows other things to burn in it. So, oxygen is a supporter of burning or supporter of combustion. Oxygen is also necessary for the process of burning or combustion of fuels, such as wood, kerosene and petrol, LPG etc.

The presence of water vapour in air is important for the working of water cycle in nature (This is because it is water vapour present in air which rises high in the sky along with hot air, gets cooled, condenses to form clouds and then brings rain on the earth).

Here, all these statements are correct. Hence, your answer will be option [D].

Air also helps in the flight of birds and aeroplanes.

Here, all these statements are correct. Hence, your answer will be option [D].

Air is present everywhere even in the soil. Oxygen is trapped in the soil and is helpful for organisms present in the soil for breathing.

The major part of air which support burning candle, is oxygen not nitrogen.

Dust and smoke present in air are harmful to living beings. Note: Breathing in air containing smoke and dust may enter our respiratory system (lungs, etc.) and damage our health.

Air plays an important role in the water cycle because hot air, being lighter, rises up and carries the water vapour high up in the sky and helps in the bringing rain.

Here, all these statements are correct. Hence, your answer will be option [D].

Here, all these statements are correct. Hence, your answer will be option [D].

The composition of air is not always exactly the same. The composition of air changes slightly from place to place and the season to season. For example, the air over in industrial cities usually has a higher amount of carbon dioxide in it, than the air over open spaces. The air in coastal areas may have more water vapour than inland areas. The air also contains more water vapour in rainy season. Similarly, the amount of dust in the air is more in windy places than other places.

Here, are all the statements are correct. Hence, your answer will be option [D].

The bubbles contain air because soil absorbs some amount of air. The air is present in the spaces between the soil particles.

When the candle burns, then oxygen of air in the gas jar is used up and carbon dioxide gas is formed. This carbon dioxide gas is absorbed or dissolved by the caustic soda solution in the trough. The absorption of carbon dioxide gas by caustic soda solution creates a vacuum or low pressure in the gas jar. The water rises up in the gas jar to fill this vacuum.

Air is a mixture of many gases. The major components of air is nitrogen gas. Almost four-fifths of air is nitrogen gas. The second major component of air is oxygen gas. About one-fifth of air is oxygen gas. In addition to nitrogen and oxygen gases, air also contains some small amounts of carbon dioxide gas water vapour and other gases (such as argon and helium etc.). The air may also contain some dust particles also.

When the divers go deep into sea water, they carry oxygen gas cylinders with them. This oxygen gas is used by divers for breathing while they are underwater. This is because there is no free oxygen in the sea water which can be used by the drivers for breathing. Therefore, the little dissolved oxygen present in sea water cannot be used for breathing (as we haven’t gills) by human beings. It can be used only by animals like fish (as they have special organ like gills) which live in water.

All the living things need nitrogen compounds for their growth. Plants use nitrogen gas of the air to make proteins. These proteins are used by the plants for their own growth as well as for the growth of human beings and other animals. Thus, nitrogen is needed by plants to make proteins.

Air is a mixture of many gases. Generally, air is mainly a mixture of nitrogen and oxygen gases with small amounts of carbon dioxide gas, water vapour and other gases. And some dust particles may also be present in air. Air contains 78 % nitrogen, 21% oxygen and remaining 1% contains carbon di oxide, water vapor, dust particles and other gases.

The plants get fertilizers, carbon dioxide, and irrigation from humans, except an oxygen. Thus, animal depends on plants for getting oxygen gas and plants depend on animals for getting carbon dioxide gas.

We know that water does not enter the bottle when it is in an inverted position, as there was no space for air to escape. When the bottle was tilted, the air was able to come out in the form of bubbles, and water filled up the empty space that the air has occupied. This activity shows that air occupies space. It fills all the space in the bottle.

If we find out that there is air in a sponge, we should squeeze the sponge in water. The air present in sponge, the bubbles comes out from the sponge when we squeeze it in water. The air shows as form of the bubbles which is present in sponge.

We get oxygen, fuel and food from plants, except carbon dioxide. Animal depends on plants for getting oxygen gas and plants depend on animals for getting carbon dioxide gas.

When the burning clothes of a person are covered with woolen blanket, then the supply of fresh air is cut off and hence the clothes stops burning or the fire gets extinguished. The three things which are essential to ignite any fire. As oxygen, heat, and fuel are frequently referred to as the “fire triangle.” The important thing to remember is: take any of these four things away, and you will not have a fire or the fire will be extinguished. Remember, wool is comparatively capable to trap much more air than any others fibres. And fire will be stop due to lack of oxygen.