The concentration of fluoride,lead,nitrate and iron in a water sample from an underground lake was found to be $1000 \ ppb, 40 \ ppb, 100 \ ppm$ and $0.2 \ ppm,$ respectively. This water is unsuitable for drinking due to high concentration of:

The gas released during anaerobic degradation of vegetation may lead to

Which of the following organs is damaged by pollutants like $SO_2$,$CO$,and $NO_2$?

Which among the following pairs consists only of herbicides?

Methane in polluted air reacts with ozone to form which of the following compounds?

$A$ factory was started near a village. Soon,the villagers began experiencing the presence of undesirable gases in the atmosphere,leading to symptoms like headaches,chest pain,colds,dry throats,and breathing difficulties. The villagers blamed the smoke emitted from the factory chimney for these problems. Describe what might have happened and provide the chemical equations to support your explanation.