Which one of have low rate of air pollution

Major source of methane in India is

Large no. of microbes and high level of water pollution indicated by

Wind blown acidic gases and particles settle down from the atmosphere on to the earth is called

If the solar radiation is less the photo chemical smog formation becomes incomplete, the air is called

Biocides is an example for

Which of the following is a secondary pollutant?.

The pH of acid rain is

Higher the BOD, lower would be