Water Pollution and Its Control

Study the graph given below and choose the option that is correctly describing the relationship between dissolved oxygen (DO) and biochemical oxygen demand (BOD):

A factory drains its waste water into the nearby lake. It has caused algal bloom. The phenomenon responsible for its cause is:

Drinking mineral water with very low level of pesticides (0.02ppm) for long periods may

Biological Oxygen Demand (BOD) is a measure of

Which of the following is biodegradable pollutant?

Fluoride pollution mainly affects

Each of the following questions has four choices. Choose the best option in each case. 

Secondary sewage treatment is mainly a 

Eutrophication of water bodies leading to killing of fishes is mainly due to the non-availability of

Which ONE of the following can NOT cause eutrophication of lakes?

The maximum concentration of harmful chemicals is expected to be found in organisms

The biomagnification of which pollutant causes a decline in the bird population?

A lake with an inflow of domestic sewage rich in organic waste may result in

A sewage treatment process in which a portion of the decomposer bacteria present in the waste is recycled into the beginning of the process, is called.

A food chain in a polluted aquatic ecosystem is given. Observe it and answer the question.

Freshwater → Algae → Fishes → Birds.

Which organisms are disturbed more due to biomagnification?

Assertion (A): Algal blooms are formed in fresh water bodies.

Reason (R): Eutrophication

Identify the correct combinations.