Approximately $P$ fraction of the solar radiation reaching the Earth is reflected by clouds and gases,and another $Q$ fraction is absorbed by them.

Increase in concentration of a toxicant at successive trophic levels is called

Jhum cultivation:
$I.$ Also called as slash and burn agriculture,is the farming practice in North Eastern states of India.
$II.$ Farmers cut down the trees of forest and burn the plant remains.
$III.$ The ash is used as a fertilizer and the land is then used for farming or cattle grazing.
$IV.$ After cultivation,the land is left for several years,so as to allow its recovery.
Which of the statements given above are correct about Jhum cultivation?

In which of the following birds is the concentration of $DDT$ found to be maximum due to their diet?

Which one of the following pairs is mismatched?

Assertion: Deforestation is one main factor contributing to global warming.
Reason: Besides $CO_2$,two other gases,methane $(CH_4)$ and $CFCs$,are also included under greenhouse gases.