The consequence of global warming may be the following:

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

The irritant red haze in traffic and congested places is due to

What do you mean by green chemistry? How will it help decrease environmental pollution?

Among the following compounds,which one is not responsible for the depletion of ozone layer?

The $BOD$ values for pure water and highly polluted water are respectively