Where did the Chipko Movement take place?

Write critical notes on the following:
$(a)$ Eutrophication
$(b)$ Biological magnification
$(c)$ Groundwater depletion and ways for its replenishment

Where was the attempt to treat wastewater by combining artificial and natural processes carried out?

The Bhopal gas tragedy in $1984$ was caused by the leakage of ......... .

In a pond near a village,a large number of fish suddenly die. Which of the following could be the reason for this?
$(a)$ Large amounts of urea and phosphate are used as fertilizers in nearby fields.
$(b)$ $DDT$ was sprayed in the entire area.
$(c)$ The pond water has become green and dirty.
$(d)$ The population of phytoplankton in the pond has decreased,reducing the photosynthetic capacity.
Which two of the above reasons are responsible?

The major pollution-causing agent is: