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CBSE Questions for Class 6 Chemistry Air Around Us Quiz 3 - MCQExams.com
CBSE
Class 6 Chemistry
Air Around Us
Quiz 3
The amount of water vapour in air is termed as:
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0%
humidity
0%
mist
0%
dew
0%
None of the above
Explanation
Humidity is the amount of water vapour present in the atmosphere.
Mist is a cloud of tiny droplets of water suspended in the air.
Dew is water in the form of droplets that appear on objects in the morning due to condensation.
Hence, option $$A$$ is correct.
Carbon dioxide, argon, methane, ozone and water vapour are also present in air in:
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0%
very small quantities
0%
very large quantities
0%
equal quantities
0%
None of these
Explanation
Carbon dioxide, argon, methane, ozone and water vapour are also present in air as very small quantities. Nitrogen is a major component.
Which gas has the highest partial pressure in atmosphere?
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0%
$$CO_2$$
0%
$$H_2O$$
0%
$$O_2$$
0%
$$N_2$$
Explanation
Air contains $$78\ \%$$ Nitrogen. So, it contributes more number of moles to partial pressure than any other gas in the atmosphere. So, it has the highest partial pressure.
Hence, Option $$D$$ is correct.
In desert areas, water vapor content is:
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0%
different
0%
higher
0%
low
0%
constant
Explanation
In desert areas, water vapor content is low because deserts are hot areas as there is a lack of water, and if there is a lack of water then there is a lack of water vapor.
Why was there no oxygen in the early atmosphere?
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0%
No water
0%
No animals
0%
No vegetation
0%
No fire
Explanation
Oxygen is produced by plants by the process of photosynthesis,
earlier there were no plants and vegetation, which's why no oxygen in the early atmosphere.
A greenhouse gas that absorbs energy and maintains earth's temperature is :
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0%
carbon dioxide
0%
nitrogen
0%
ozone
0%
oxygen
Explanation
A greenhouse gas that absorbs energy and maintains the earth's temperature is
carbon dioxide
.
Option $$A$$ is correct.
Plants also consumes ________ for respiration.
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0%
Carbon monoxide
0%
Oxygen
0%
Nitrogen
0%
Both A and B
Explanation
Plants also consume $$\text {oxygen}$$ for respiration.
At night, when photosynthesis can’t take place, plants continue to consume oxygen but they don’t release any back into the atmosphere.
As the amount of oxygen consumes by the plants is very low during respiration so it doesn't affect the oxygen levels of the atmosphere.
Hence the correct option is $$B$$.
Second most abundant constituent of dry air in terms of volume after nitrogen is:
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0%
carbon dioxide
0%
helium
0%
oxygen
0%
sulphur dioxide
Explanation
Second most abundant constituent of dry air in terms of volume after nitrogen is oxygen. Nitrogen and oxygen together constitute 99% of air.
Which one of the following has the major part of air?
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0%
Nitrogen
0%
Oxygen
0%
Carbondioxide
0%
Helium
Explanation
The air contains highest $$\%$$ of Nitrogen gas ( $$78\ \%$$). Hence, option $$A$$ is correct
Which of these statements are true about air?
(i) Air is a mixture of several types of gases.
(ii) Air exerts pressure.
(iii) The composition of air is constant in the atmosphere.
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0%
(i) and (ii)
0%
(ii) and (iii)
0%
(i) and (iii)
0%
(i), (ii) and (iii)
Explanation
Air is mixture of several gases like nitrogen, oxygen and carbon dioxide.
As air is like gas it exerts pressure.
The composition of air varies in the atmosphere.
Plant absorb ________ to make their own food.
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0%
oxygen
0%
carbon dioxide
0%
nitrogen
0%
none of the above
Explanation
Plants make their own food by the process of photosynthesis. To carry out photosynthesis, plants need carbon dioxide, water, and nutrients. The process of photosynthesis takes place only in the presence of sunlight, and oxygen is given out as a by-product.
Hence the option B is correct.
To increase the percentage of oxygen in the atmosphere:
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0%
plant more trees
0%
kill all living beings
0%
cut down trees
0%
protect animal life
Explanation
Planting more trees directly increases the oxygen amount by the process of photosynthesis in which oxygen is formed and releases into the atmosphere which in turn increases the percentage of oxygen in the atmosphere.
Hence the option A is correct.
Balance of oxygen and carbon dioxide in atmosphere is maintained by:
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0%
plants
0%
animals
0%
humans
0%
all of the above
Explanation
The balance of oxygen and carbon dioxide is maintained by plants, animals, and humans. Green plants use up carbon dioxide during photosynthesis and release oxygen as a product.
Whereas, animals and humans use up oxygen during respiration and release carbon dioxide as a by-product. This maintains the overall balance of oxygen and carbon dioxide.
Hence option D is correct.
The gas X is only about 20 parts out of 100 parts of air in the atmosphere. It is needed for decomposition of organic matter. The gas X is
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0%
Carbon dioxide
0%
Water vapor
0%
Oxygen
0%
Nitrogen
Explanation
Air is a mixture of gases, mainly containing nitrogen (about 78% by volume) and oxygen (about 21%). Oxygen is needed for decomposition of organic matter.
Refer to the given flow chart and identify X, Y and Z.
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0%
$$(X)O_{2}, (Y)CO_{2}, (Z) He$$
0%
$$(X)CO_{2}, (Y)O_{2}, (Z)N_{2}$$
0%
$$(X)N_{2}, (Y)CO_{2}, (Z)O_{2}$$
0%
$$(X)O_{2}, (Y)He, (Z)CO_{2}$$
Which does not need help of air in its movement?
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0%
Firki
0%
Weather cock
0%
Ceiling fan
0%
Sailing yacht
Explanation
All the other mentioned activities require natural air for them to move whereas a ceiling fan is moved by electricity.
The correct answer is option (C).
Which of the following is not true about air?
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0%
Air can be separated into components.
0%
It can be liquefied
0%
Birds can fly due to presence of air
0%
Air has a chemical formula
Explanation
The statement which is not true about air is that it has a chemical formula. Air has no chemical formula. It is a mixture of gases.
Hence, option D is correct.
Oxygen is returned to the atmosphere mainly by :
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0%
Burning of fossil fuel
0%
Respiration
0%
Photosynthesis
0%
Fungi
Explanation
During the process of photosynthesis, plants lead to the formation of complex sugars (food) using water and carbon dioxide in the presence of sunlight and release oxygen into the environment.
While processes like burning fuels and respiration release carbon dioxide into the air.
State whether true or false:
Oxygen is returned to the atmosphere by one major process, which is, respiration.
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0%
True
0%
False
Explanation
Photosynthesis is the major process by which oxygen is returned to the atmosphere. During the process of respiration carbon dioxide is being released into the atmosphere and oxygen is used up.
Write 'true' or 'false':
Air is a compound.
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0%
True
0%
False
Explanation
False,
Air is composed of many gases, most predominantly nitrogen, oxygen, and argon. Therefore, it is a mixture rather than a compound.
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