Matching the column I and column II 1

Column I	Column II
1. GHG 2. CFCs 3. PAN 4. Lichen	(a) Paedogenesis (b) Methane (c) Global warming (d) Smog

1) GHG (c) Global Warming

A greenhouse gas is a gas that traps infrared rays and prevents heat from escaping the earth, thus causing global warming.

2) CFCs (b) Methane

A chlorofluorocarbon is a organic compound that is a volatile derivative of methane, ethane and propane.

3) PAN (d) Smog

Peroxyacyl nitrate is a type of air pollution that is part of photochemical smog. Basically PAN’s are respiratory and eye irritants.

4) Lichen (a) Paedogenesis

Lichens grow on rock surface and bring about biological weathering of rocks. While they grow they release some substances that cause rock suface to powder form a thin layer of soil. Paedogenesis is the final step in soil formation where bacteria and fungi decompose organic matter leading to humification.