of Air and Water
Q41. What is Ganga Action Plan? When was it launched? What was
An ambitious plan to save the river, called the Ganga Action Plan was launched
in 1985. It aimed to reduce the pollution levels in the river. Recently a study
by the World Wide Fund for Nature (WWF) found that Ganga is one of the ten most
endangered rivers in the world. The pollution levels have been rising for many
years. This stage is reached because the towns and cities, through which the
river flows, throw large quantities of garbage, untreated sewage, dead bodies,
and many other harmful things, directly into the river. In fact the river is
“dead” at many places where the pollution levels are so high that aquatic life
Q42. Prepare a brief speech on global warming that you have to
make in your class.
CO2 is one of the gases responsible for this effect. Carbon dioxide is
needed by plants. But if there is excess of CO2 in the air, it acts
as a pollutant. On the one hand, CO2 is continuously being released
because of human activities. On the other hand, area under forests is
decreasing. Plants utilise CO2 from the atmosphere for
photosynthesis, thereby decreasing the amount of CO2 in the air.
Deforestation leads to an increase in the amount of CO2 in the air because
the number of trees which consume CO2 is reduced. Human activities,
thus, contribute to the accumulation of CO2 in the atmosphere. CO2
traps heat and does not allow it to escape into space. As a result, the average
temperature of the earth’s atmosphere is gradually increasing. This is called global
Q43. What are the harmful effects of water pollution?
Following are the harmful effects of water pollution:
Water contaminated with sewage may contain bacteria,
viruses, fungi and parasites which cause diseases like cholera, typhoid and
Excessive quantities of chemicals which get
washed from the fields act as nutrients for algae to flourish. Once these algae
die, they serve as food for decomposers like bacteria. A lot of oxygen in the
water body gets used up. This results in a decrease in the oxygen level which
may kill aquatic organisms.
Hot water released by power plants and
industries raises the temperature of the water body and adversely affecting the
animals and plants living in it.
The chemicals released include arsenic,
lead and fluorides which lead to toxicity in plants and animals.
Q44. What are the main sources of air pollution?
How does air get polluted?
Ans. Sources of air pollution
Natural sources like smoke and dust arising
from forest fires or volcanic eruptions causes air pollution.
Pollutants are also added to the atmosphere
by human activities. The sources of air pollutants are factories, power plants,
automobile exhausts and burning of firewood and dung cakes.
Pollutants like sulphur dioxide and
nitrogen dioxide gases react with the water vapour present in the atmosphere to
form sulphuric acid and nitric acid and causes acid rain.
Carbon monoxide is produced from incomplete
burning of fuels such as petrol and diesel. It is a poisonous gas.
Chlorofluorocarbons (CFCs) which are used
in refrigerators, air conditioners and aerosol sprays cause air pollution.