Class 6 Science Chapter 11 MCQ

As we go up above the sea level, the atmospheric pressure goes on decreasing and the amount of oxygen also decreases at higher altitude. This is why, mountaineers carry oxygen, cylinders with them.

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.

If burning coal is covered with a vessel, it stops burning after sometime. This is because when we cover the burning coal with a vessel, then the supply of oxygen of fresh air to the burning coal is cutoff. And in the absence of oxygen or air, the coal stops burning. The coal fire gets extinguished.

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).

Air also helps in the flight of birds and aeroplanes.

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

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

Here, all these statements are incorrect. Hence, your answer will be option [D]. In option [A]: Air helps in the dispersal of seeds and pollen of flowers of several plants. In option [B]: Air has role for burning of phosphorus. Thus phosphorus reacts with air. In option [C]: Air has big role for flying aeroplanes and helicopters.

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

Nitrogen is present in the largest amount in the atmosphere. It occupies 78.09% of atmosphere.

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.

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

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. Remember the composition of air is not always exactly the same.

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.

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 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.

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.

Carbon monoxide is produced by the incomplete combustion of carbon-containing fuels, such as gas (domestic or bottled), coal, oil, coke and wood. Gas stoves, fires, heating boilers, gas-powered water heaters, paraffin heaters, and solid fuel-powered water heaters are all potential sources of carbon monoxide. Air do not contain these types of gases. 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. Remember the composition of air is not always exactly the same.

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.

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.