A student collected samples from two water bodies A and B in a metro city. The biochemical oxygen demand for 'A' is 3 ppm while for B is found to be 18 ppm. Which one of the following is true? 
1. Both A and B are clean 
2. Both A and B are polluted 
3. A is clean but B is polluted 
4. A is polluted but B is clean 

Match List-1 with List-II

List-I	List-II
(a). $2{\mathrm{SO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{SO}}_3\left(\mathrm{g}\right)$	(i). Acid rain
(b).  $$	(ii). Smog
(c). ${\mathrm{CaCO}}_3+{\mathrm{H}}_2{\mathrm{SO}}_4\to$ ${\mathrm{CaSO}}_4+{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2$	(iii). Ozone depletion
(d). ${\mathrm{NO}}_2\left(\mathrm{g}\right)\stackrel{\mathrm{hv}}{\to }\mathrm{NO}\left(\mathrm{g}\right)+\mathrm{O}\left(\mathrm{g}\right)$	(iv). Tropospheric pollution

Choose the correct answer from the options given below:

The incorrect statement about carbon monoxide is-

Among the following, the one that is not a greenhouse gas is:

1. Sulphur dioxide

2. Nitrous oxide

3. Methane

4. Ozone

Which oxide of nitrogen is not a common pollutant introduced into the atmosphere both due to natural and human activity?

1. N₂O₅
2. NO₂
3. N₂O
4. NO

A gas that is not common component of photochemical smog is-

1. Ozone

2. Acrolein

3. Peroxyacetyl nitrate

4. Chlorofluorocarbons