In the last few decades,the most serious nuclear reactor accident and the $MIC$ gas tragedy occurred in:

Increase in concentration of the toxicant at successive trophic levels is known as

Pesticides disturb the ecosystem by eliminating the

Given below are two statements:
Statement $I$: Electrostatic precipitator is most widely used in thermal power plants.
Statement $II$: Electrostatic precipitator in thermal power plants removes ionising radiations.
In the light of the above statements,choose the most appropriate answer from the options given below:

Use of lead-free petrol or diesel is recommended to reduce the pollutants emitted by automobiles. What role does lead play?

$BOD$ is a measure of what?