8-Pollution
Q. 1
True or False. Explain your statement :
Ans.
(1)
False. (Even if washing of soiled clothes is done in running water, it will
cause pollution as the dirt and the waste materials will be added to water.
This certainly will cause water pollution.)
(2)
True. (Most of the electricity is generated in India by burning coal. The power
generation plants thus cause lots of air pollution. More the electricity is
used by using more appliances, there will be more pollution. However, only
power generation through solar energy cannot cause pollution.)
Q 2.
Match the column.
Ans.
(1) Water containing cobalt - Paralysis.
(2) Methane gas - Skin cancer
(3)
Water containing lead – Mental retardation
(4)
Sulphur dioxide - Irritation of eyes
(5)
Nitrogen dioxide – Inflammation of lungs.
Q. 3
Questions based on classification of pollutants :
• Classify the following pollutants into natural and
manmade categories.
Sewage,
dust, pollen grains, chemical
fertilizers, vehicular smoke, algae, pesticides, waste of animals and birds.
Ans.
Natural
Man-made Natural
• Sewage • Dust
(Natural)
• Dust (Construction related) • Pollen grains
• Algae
•
Chemical fertilizers •
Waste (Excreta) of animals and birds
• Vehicular smoke
• Pesticides
Q.4
Following are some statements about pollution. Which type of pollution do those
express :
Ans.
(1) Air pollution-Smog The sentence should have the word *Smog and not fog.
Smog is fog with smoke. Only fog cannot be polluting. but the smog is.)
(2)
Water pollution - Contaminated food and water due to bacteria or virus
(3)
Air pollution due to pollens
(4)
Soil pollution
(5)
Air pollution due to traffic
Q. 5
Read the passage and identify the
sentences expressing types of pollution.
Ans.
(1) It takes about an hour to go to the school. (Due to traffic jam, Nilesh is
spending more time in polluted, contaminated air.)
(2) He
faces the heavy traffic. (Large scale combustion of fossil fuel.)
(3) He
is facing the problem of asthma. (Air pollution - Harmful to human health.)
(4)
The heaps of garbage at many places. (Solid waste - Land pollution.)
(5) Foul smell of human and animal wastes. (Biological pollution, air pollution.)
(6)
Blackish water with foul smell was flowing in a stream. (Improper sewage
management - Water pollution.)
(7) He developed some abdominal disease within few
days. (Water pollution - Effect on
human
health.)
Q. 6
Answer the following:
(1)
What is pollution?
Ans.
Contamination of environment that can harmfully affect the environment is
called pollution.
(2)
What are Pollutants?
Ans.
The products which affect the normal functioning of ecosystem and have an
adverse effect on plants, animals and humans are called pollutants.
(3)
Which are visible pollutants known to you?
Ans.
(1) The polluting substances that are seen easily with the naked eyes can be
called as visible pollutants. E.g. Solid wastes, plastic articles, plastic
bags, the suspended things in the water, metal refuse, etc.
(4)
Which are invisible pollutants?
Ans.
The pollutants which are completely dissolved in water or mixed in the air,
cannot be seen and hence they can be called invisible pollutants. Since they
are not seen, we remain unaware about the presence these pollutants. E.g. the
insecticides sprea on the crops. Aerosols, many hazardous gases in the air,
toxic compounds that totally soluble in water, etc.
(5)
What is greenhouse effect?
Ans.
(1) Greenhouse effect is the phenomenon due to which global warming and climate
change occur.
(2)
The earth receives solar energy in the form of heat from the sun. The surface
of earth absorbs this heat and reflects it back to the atmosphere as infrared
radiation. Some of this heat energy goes directly into space. (3) But due to pollution
there is an envelope of CO2,
CH4
and water vapours in the atmosphere, some of these radiations are absorbed by
these gases. This radiation is sent back to the earth surface in the form of heat
energy. (4) This causes warming of the earth which is called greenhouse effect.
It later results in global warming. (5) The gases (CO2, CH4, N2O and CC12F2) contributing to greenhouse effect
are called greenhouse gases. (6) More and more burning of fossil fuels and
allied activities by humans cause more and more greenhouse effect. (7) The
worst impact of greenhouse effect is global warming and climate change.
(6)
Explain relation between greenhouse effect and global warming.
Ans . Because
of greenhouse effect, there is increase in the global temperature. The heat on
the earth remains trapped due to due to envelope of greenhouse gases. The
percentage of carbon dioxide and methane is constantly increasing and hence
there is increase in the temperature too. Thus the greenhouse effect is
directly related to the global warming
Effects
of this relation between greenhouse effect and global warming are as follows:
(1)
The polar ice caps and the glaciers at both the poles are melting due to
increased temperature.
(2)
The oceans' water is rising due to this melted ice. The sea level rise is
causing coastal land submergence. The islands at Various regions are threatened
of drowning.
(3)
Many species of living organisms are already extinct due to global warming. The
rest are also threatened.
(4) Wild
animals are showing weird migrations. Polar bear is endangered.
(5)
The increased temperature of the oceanic water is causing many changes in the
tides and currents. This results into increased occurrence of cyclones,
hurricanes and cloud bursting. The natural disasters are rising in last decade.
(6)
The agricultural production is decreasing. The regions with less rainfall are
facing draughts.
(7)
How does the pollution occur due to vehicles? Give the names of vehicles
causing least pollution.
Ans.
(1) More than 50% of the air pollution is caused by vehicular traffic.
(2)
Particulate matter, unburnt hydrocarbons, CO, nitrogen oxides and carcinogenic
hydrocarbons are present in the automobile exhausts.
(3)
Fossil fuels like petrol, diesel, natural gas, gasoline, etc. which are burnt
to run the automobiles lead to the emission of CO, and other gases.
(4)
Therefore, vehicles are said to be the major contributors to air pollution.
(5)
The only vehicle which is nonpolluting is bicycle. The four-wheelers which are
battery operated are also manufactured recently. These two types of vehicles
are eco-friendly. The cars that run on C.N.G. are also said to be lesser
polluting.
(8)
What is acid rain?
Ans.
(1) When rainwater contains harmful amounts of nitric and sulphuric acids, it
is called acid rain.
(2)
Burning of fossil fuels such as coal, wood, petroleum, etc. releases nitrogen
oxide and sulphur oxide into the atmospheric air.
(3)
Since these oxides are soluble in water, they dissolve in rainwater. Nitrogen
and sulphur oxides dissolved in large quantities of water vapour form acids
like nitric acid, nitrous acid, sulphurous acid and sulphuric acid.
(4)
These acids mix with mist, drops of rainwater and snow. They change their
composition and fall back on the
ground in the form of acid rain.
(5)
Effects of acid rain are as follows:
(1)
Increase in the acidity of soil and water bodies.
(ii)
Damage to the trees.
(iii)
Water becomes unsuitable for fish and wildlife.
(iv)
Buildings, statues, sculptures, bridges, monuments and fences are corroded due
to acid rain. Thus, acid rain damages our national assets.
(v)
Acid rain affects agriculture and crop lands.
(9) Suggest four preventive measures for air
pollution.
Ans.
The following methods are adopted to control air pollution from the industries
:
(1)
The source discharge is diluted by tall chimneys.
(2)
There are source correction methods like changing the raw material, equipment
modification, process modification, etc.
(3)
Effective pollution controlling equipment like dust collectors, electrostatic
precipitators, wet scrubbers, etc. should be used.
(4)
There should be ban and control over atomic tests and chemical weapons on the
international level.
(10) What
are natural reasons/causes for
water pollution?
Ans.The
natural causes of the water pollution:
(1) If
organic pollutants are added to the water there is overgrowth of weeds such as
Eichhornia. The growth of algae also makes the water unsuitable for
consumption. These aquatic plants release oxygen during day time but by night
they require oxygen thus depleting the dissolved oxygen level. The natural
characters of water are then changed.
(2)
The decomposing matter when added to the water make it polluted and stinking.
(3)
Due to deposition of sludge or eroded soil, the rivers change their path and
divert from original flow. The currents are also changed. Deposition of sludge
makes the water polluted.
(4)
Due to soil erosion, surrounding the water bodies, the microbes, bacteria,
protozoans and the worms and larvae of nematodes enter the water causing severe
biological pollution. Many inorganic pollutants are also added to the water.
The fungi and bacteria present in the water make it non-potable. Such water
spreads the water, borne
diseases.
