In this soil conservation method,several grasses are left out in the soil after the crop is harvested.

The Kyoto Protocol has specified the commitments of different countries to:

$A$ large number of fish suddenly die in a lake near a village. Which of the following could be the reason for this?
$(a)$ Excessive use of urea and phosphate fertilizers in nearby fields.
$(b)$ Spraying of $DDT$ in the entire area.
$(c)$ The lake water has turned green and murky.
$(d)$ The population of phytoplankton in the lake has decreased,reducing the photosynthetic capacity.
Which two of the above reasons are responsible?

Provide the full names for the following abbreviations:
$(i)$ $HFC$
$(ii)$ $CFC$

Arrange $CFC, CH_4, N_2O$ and $CO_2$ in decreasing order according to their contribution in the greenhouse effect.

Internationally,it is recognized that desertification is a major problem nowadays,primarily due to which of the following?