Which constituent of the atmosphere is likely to change if the forest cover is removed ?

As a result of deforestation is –

By what degrees has the mean global temperature increased in the 20th centrury

Today the concentration of green house gases is very high because of

Carbon dioxide is called green-house gas because it is

Which of the following strategy is not a correct approach to reduce global warming ?

Reducing the green house gas emission by limiting the use of fossil fuels
Increase the vegetation cover particularly the forest for photosynthetic utilization of CO₂
Minimizing the use of nitrogen fertilizers in agriculture for reducing N₂O emission.
Increasing the use of air conditioners, refrigeration unit and production of plastic foams and propellants in aerosal spray cans

Frequent occurrence of water blooms in a lake indicates

Solution

In polluted water nitrogen and phosphorus (from sewage)are accumulated which results in excessive growth of algae on water surface. Excessive growth of algae called water bloom. Due to death and decomposition of organic matter O₂ not available to aquatic animals.

Which among the following is likely to have the highest levels of D.D.T. depositions in its body ?

Solution

DDT is a non-biodegradable pollutant. This often biologically magnified with their subsequent movement in food chain. Its concentration in 'sea gull' will be highest.

Fishes die by sewage because

When huge amount of sewage is dumped into a river, the BOD will

Solution

The degree of pollution is directly proportional to BOD,therefore more the organic pollution (Specially sewage),the more would be BOD of water.

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