The chemical added to leaded petrol to prevent the deposition of lead in the combustion chamber is

State the sources of dissolved oxygen in water.

Do you observe any soil pollution in your neighbourhood? What efforts will you make for controlling the soil pollution?

Given below are two statements :-
Statement $I :$ The value of the parameter "Biochemical Oxygen Demand $(BOD)$" is important for survival of aquatic life.
Statement $II :$ The optimum value of $BOD$ is $6.5 \ ppm$.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which of the following is not considered to be a pollutant?

Addition of phosphate fertilisers to water bodies causes