Match the terms given in Column I with the compounds given in Column II.

Column I Column II
A. Acid rain 1. CHCl2-CHF2
B. Photochemical smog 2. CO
C. Combination with hemoglobin 3. Unsaturated hydrocarbons
D. Depletion of the ozone layer 4. SO2

Codes

A B C D
1. 4 2 3 1
2. 1 2 3 4
3. 4 3 2 1
4. 4 1 3 2
HINT: When chlorine and bromine atoms come into contact with ozone in the stratosphere, they destroy ozone molecules.
Explanation:
A. Acid rain is formed when sulfur dioxide (SO2) and nitrogen oxides (NOX) are emitted into the atmosphere and transported by wind and air currents. 
B. Photochemical smog is formed by unburnt fuel (unsaturated hydrocarbon).
C. Carbon monoxide and hemoglobin is poisonous because CO combines with hemoglobin and forms a stable complex. Due to complex formation hemoglobin is unable to form a complex with oxygen.
D. Chlorofluorocarbon (CHCl2-CHF2) cause ozone depletion.