Name one source and one harmful effect of each of the following air pollutants :
(a) Sulphur dioxide
(b) Nitrogen oxides
(c) Carbon monoxide
(d) Chlorofluorocarbons (CFCs)
Which of the following is not an air pollutant?
(b) Sewage
(c) CFCs
(d) SPM
Ozone layer depletion is caused due to ___.
(CFCs/methane/nitrogen oxides/sulphur dioxide)