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CBSE Questions for Class 8 Chemistry Pollution Of Air And Water Quiz 10 - MCQExams.com
CBSE
Class 8 Chemistry
Pollution Of Air And Water
Quiz 10
Which of the following pollutants is not harmful to the lungs?
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$$CO$$
0%
$$SO_2$$
0%
$$CO_2$$
0%
$$NO_2$$
Explanation
$$A)$$ The respiratory system struggles to distribute air around the body because carbon monoxide deprives the blood cells of oxygen. This results in shortness of breath, particularly when undertaking strenuous activities. As a result, the airways begin to swell causing even less air to enter the lungs.
$$B)$$ High concentrations of $$SO_2$$ can affect lung function, worsen asthma attacks, and worsen existing heart disease in sensitive groups. This gas can also react with other chemicals in the air and change to a small particle that can get into the lungs and cause similar health effects.
$$C)$$ $$CO_2$$ is not poisonous; as a gas, $$CO_2$$ itself will not hurt you. This is an important fact to remember, as carbon dioxide is a vital part of the environment. The human breathing mechanism actual revolves around $$CO_2$$, not oxygen. Without carbon dioxide, humans wouldn't be able to breathe.
$$D)$$ When nitrogen dioxide is inhaled at high enough levels, it reacts with and damages lung cells, including those cells that fight infection. This damage can affect breathing and may increase the risk of respiratory infections.
$$\mathbf{Hence\ the\ correct\ answer\ is\ option\ (C)}$$
Which of these are correct about greenhouse effect?
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It results in global warming.
0%
It results in lowering levels of oceans over the years.
0%
Carbon dioxide is one of the main chemical species responsible for it.
0%
Methane and chlorofluorocarbons also contribute to it.
Low visibility during cold weather can be due to:
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fog
0%
smoke from industries and vehicles
0%
both A and B
0%
none of A or B
Explanation
During cold weather, water droplets instead of moving up at a higher altitude stay near the earth's surface and cause fog. Along with this, a lot of vehicular emissions and smoke from industries contain oxides of nitrogen which combine with other air pollutants and fog to form smog.
The smog causes breathing difficulties such as asthma, cough and wheezing in children. Also as they both remain suspended in the air causing the visibility to reduce during cold weather.
The type of pollution which is likely to affect Taj Mahal in Agra to a greater extent is
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Air pollution
0%
Soil pollution
0%
Water pollution
0%
Noise pollution
Explanation
Air pollution is harming
the Taj Mahal in such a way that the white marble of the monument corroding and yellowing marble.
Hence, Option "A" is the correct answer.
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.
Choose the correct alternative from the choice given for the following statements:
Air consists of:
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oxygen
0%
nitrogen
0%
carbon dioxide
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All of these
Explanation
Answer is Option D.
Air in Earth's atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen. Air also has small amounts of lots of other gases, too, such as carbon dioxide, neon and hydrogen.
Write 'true' or 'false':
The composition of air was discovered by Lavoisier.
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True
0%
False
Explanation
In June $$1783$$, Lavoisier reacted oxygen with inflammable air, obtaining "water in a very pure state." He correctly concluded that water was not an element but a compound of oxygen and inflammable air, or hydrogen as it is now known. To support his claim, Lavoisier decomposed water into oxygen and inflammable air.
So, the given statement is false.
Write 'True' or 'False' in front of the following statement:
The trapping of solar heat energy in the earth's atmosphere is called the greenhouse effect.
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True
0%
False
Explanation
The trapping of solar heat energy by certain gaseous molecules present in the earth's atmosphere is called the greenhouse effect.
So, the given statement is true.
What is the reason of increase in temperature?
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Acid rain
0%
Nuclear accidents
0%
Greenh
ouse effect
0%
Both A nad B
Explanation
The atmosphere today contains more greenhouse gas molecules, so more of the infrared energy emitted by the surface ends up being absorbed by the atmosphere. Since some of the extra energy from a warmer atmosphere radiates back down to the surface, Earth's surface temperature rises.
Hence, option D is correct.
Which is the most abundant gas in the atmosphere?
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$$ Oxygen $$
0%
$$ Nitrogen $$
0%
$$ Carbon dioxide $$
0%
$$ Other \ gases $$
Explanation
The
air
in Earth's atmosphere is made up of approximately $$78$$% nitrogen and $$21$$% oxygen.
Air
also has small amounts of lots of other gases, too, such as carbon dioxide, neon, and hydrogen
Hence answer is $$ Nitrogen $$
Which one of the following has the major part of air?
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Nitrogen
0%
Oxygen
0%
Carbondioxide
0%
Helium
Explanation
The air contains highest $$\%$$ of Nitrogen gas ( $$78\ \%$$). Hence, option $$A$$ is correct
Identify the correct statement.
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Non-conventional source of energy more pollution
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Ozone is harmless gas present in the atmosphere
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Chlorofluorocarbons break down to chlorine atoms by ultraviolet radiation
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Trees do not help in decreasing sound pollution.
Explanation
Chlorine atoms are released in the atmosphere by chloroflurocarbons due to dissociation by $$UV$$ radiations. Hence option (C) is correct.
Identify the gas "odourless, colourless, heavier than air, supports combustion".
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Nitrogen
0%
Oxygen
0%
Carbondioxide
0%
Water vapour
Explanation
Oxygen is a
colorless
,
odorless,
and tasteless
gas
that
supports
life and
combustion and heavier than air.
hence the correct answer is B
Sewage containing organic waste should not be disposed in water bodies because it causes major water pollution. Fishes in such a polluted water die because of :
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large number of mosquitoes
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increase in the amount of dissolved oxygen
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decrease in the amount of dissolved oxygen in water
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clogging of gills by mud
Explanation
Sewage containing organic waste should not be disposed of in water bodies because it causes water pollution. Microorganisms in water try to decompose the untreated sewage. While doing so they use oxygen and, so the oxygen level in such water decreases. Thus fish in such polluted water die, because of a decrease in the amount of dissolved oxygen in the water
Fish die in water bodies polluted by sewage due to :
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pathogens
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reduction in oxygen
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foul smell
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none of these
Explanation
Reduction in dissolved oxygen.
When sewage is drained into water bodies it results in a reduction of oxygen, this is because oxygen is get used in the decomposition of organic matter of the sewage. Due to this effect oxygen concentration falls below the level at which fish can survive and results in fish die.
Hence, option $$B$$ is correct.
Global warming may result in :
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flood
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decrease in temperature of the earth's surface
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Increase in temperature of earth's surface.
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Both $$A$$ and $$C$$
Explanation
Global warming is the rise or increase in temperature of earth's surface due to greenhouse gases. This global warming effect also leads to increase in sea level which ultimately leads to floods in coastal area.
Hence, option $$D$$ is correct.
The consequences of global warming is(are):
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an increase in average temperature of the earth
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melting of glaciers
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rise in the sea level
0%
none of these
Explanation
Global warming causes an increase in the average temperature of the earth which leads to the melting of glaciers and polar ice caps, ultimately leading to the rise in the sea level.
Which of the following gases is not a green house gas ?
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$$CO$$
0%
$$CO_2$$
0%
$$CH_{4} $$
0%
$$H_{2}O$$ vapour
Explanation
CO is not a greenhouse gas as it does not absorb IR energy strongly. Also, it does not increase the temperature of the earth's atmosphere.
Phosphate-containing fertilizers cause water pollution. Addition of such compounds in water bodies cause ________.
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enhanced growth of algae
0%
decrease in amount of dissolved oxygen in water
0%
deposition of calcium phosphate
0%
increase in fish population
Explanation
The addition of phosphate fertilizers to water bodies causes enhanced growth of algae. This decreases the oxygen for sea animals. This results in water pollution.
Hence, options A and B both are correct.
Air is a ______.
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Mixture
0%
Compound
0%
Pure substance
0%
None of these
The Ganga action plan
aimed ________.
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to increase the water level of Ganga
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to build a bridge on Ganga river
0%
to reduce the pollution level in the river Ganga
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to increase trade through the Ganga river
Explanation
The Ganga action plan was launched in 1985. It aimed to reduce the pollution level in the river Ganga.
The industrial cause of polluting river Ganga is
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bathing
0%
discharging harmful chemicals
0%
throwing garbage, flowers, idols of gods and goddesses
0%
None of these
Explanation
Many industries discharge harmful chemicals into rivers and streams, causing the pollution of rivers like the Ganga. Examples are oil refineries,
paper factories, textile and sugar mills, etc.
Option $$B$$ is correct.
The pie chart shows the different gases that contribute to the total composition of air.
What atmospheric gas does the area marked as R in the pie chart represent?
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Nitrogen
0%
Carbon dioxide
0%
Oxygen
0%
Water vapour
Explanation
The area marked as R shows the atmospheric gas-Nitrogen. Nitrogen is the most abundant gas. It comprises about $$78.08\%$$ of our atmosphere thus comprising the most about of our atmosphere.
The graph given here shows the rise in global temperature from $$1850$$ to $$2019$$.
How will this affect the earth?
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An increase in temperature will cause a reduction in the emission of greenhouse gases
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An increase in temperature will cause glaciers to melt and sea levels to rise dramatically
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An increase in temperature will lead to repair and thickening of the ozone layer
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An increase in temperature will lead to better crop production and food security
Explanation
Global warming is the gradual heating of Earth's surface oceans and atmosphere caused by activities of human-like burning of fossil fuel deforestation etc. The increase in global annual temperature leads to the melting of glaciers which increases the sea level drastically causing destruction.
Hence, option D is the correct answer.
Assertion (A): Acid rain reduces the fertility of the soil.
Reason (R): Acid rain has a corroding effect on marble buildings.
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Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
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Both Assertion and Reason are correct but Reason is not correct explanation for Assertion
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Assertion is correct and Reason is incorrect
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Assertion is incorrect and Reason is incorrect
Explanation
Acid rain inhibits the activity of symbiotic nitrogen-fixing bacteria present in the nodules of the leguminous family. Hence, acid rain reduces the fertility of the soil.
Acid rain has a corroding effect on marble buildings. Sulphuric acid present in acid rain reacts with calcium carbonate present in the marble.
$$CaCO_3+H_2SO_4 \rightarrow CaSO_4 + H_2O + CO_2 \uparrow$$
Global warming is mainly due to the increase of:
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methane and $$NO_2$$ in atmosphere
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methane and $$CO_2$$ in atmosphere
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methane and $$O_3$$ in atomsphere
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methane and $$CO$$ in atmosphere
Explanation
The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. The effect of this is global warming.
Global warming is due to the increase of greenhouse gases like methane and $$CO_2$$ in the atmosphere. Methane and carbon dioxide have a major contribution to global warming.
Hence, option $$B$$ is correct.
Gases referred as 'greenhouse gases' are:
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$$CO_2,\ O_2,\ NO_2,\ NH_3$$
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chlorofluorocarbon, $$CO_2,\ NH_3,\ N_2O$$
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$$CH_4,\ N_2,\ CO_2,\ NH_3$$
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chlorofluorocarbon, $$CO_2,\ CH_4,\ N_2O$$
Explanation
The most significant greenhouse gases are water vapour (H$$_2$$O), carbon dioxide (CO$$_2$$), methane (CH$$_4$$) and nitrous oxide (N$$_2$$O). Chlorofluorocarbons (CFCs), once used as refrigerants and aerosol propellants until they were phased out by international agreement, are also greenhouse gases.
Which among the following gas is most responsible for global warming?
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Nitrogen
0%
Methane
0%
Carbon dioxide
0%
Carbon monoxide
Explanation
Carbon dioxide is a byproduct of combustion of fossil fuel. It is a greenhouse gas contributing to global warming.
According to WHO, the soft water has 0 to _____ milligram per litre as $$CaCO_3.$$
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0%
60
0%
120
0%
180
0%
150
Explanation
Concentration as $$CaCO_3$$
Indication
0 to 60 mg/L
Soft water
60 to 120 mg/L
Moderately hard water
120 to 180 mg/L
Hard water
>180 mg/L
Very hard water
The following values are used to give an indication about water hardness.
Exchange of radiations that keep Earth warm is known as:
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ozone layer depletion
0%
greenhouse effect
0%
depletion of ozone layer
0%
None of the above
Explanation
The exchange of outgoing and incoming radiations that keep Earth warm is known as the greenhouse effect.
Hence option $$B$$ is correct.
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