At the beginning of the twentieth century,forests covered about ........... of the land area of India. (in $\%$)

What percentage of global warming is contributed by $CO_2$ (in $\%$)?

Where are Ecosan toilets used?

Rice fields produce an important greenhouse gas. Name it.

Consider the following reasons for the massive fish mortality observed in a lake near a village within a few days:
$(1)$ Excessive use of urea and phosphate fertilizers in nearby crops.
$(2)$ Spraying of $DDT$ using aircraft.
$(3)$ The lake water turned green and foul-smelling.
$(4)$ Initial decrease in phytoplankton in the lake leads to a maximum decrease in photosynthesis.
Which of the above reasons are responsible for the massive fish mortality?

What is the biological concentration of $DDT$ in the body fat of Indian people?