Question

Why do not lichens occur in Delhi whereas they commonly grow in Manali or Darjeeling?

Answer 1

1. Lichens grow in a pollution-free environment and they are sensitive to SO₂.
2. Delhi has a maximum number of vehicles which causes more pollution.
3. The exhaust from the vehicles increased the concentration of SO₂ and it kills lichens.
4. In Manali and Darjeeling, vehicular pollution is less which is the main reason for the growth of lichens.