Eutrophication can lead to

Methemoglobinemia is due to

Which of the following statements are correct?
a) $F^{-}$ ion concentration above $2 \ ppm$ causes brown mottling of teeth
b) The maximum limit of nitrate in drinking water is $400 \ ppm$
c) Depletion of ozone layer leads to cataract and skin cancer
d) The irritant red haze in the traffic is due to oxides of sulphur

Which substance is now used in refrigerators instead of $CFC$s?

Explain tropospheric pollution in $100$ words.

Eutrophication causes: