Soil conservation is a practice in which soil:

Assertion: Presently,the global atmosphere is warming up.
Reason: The depletion of the stratospheric ozone layer has resulted in an increase in ultraviolet radiations reaching the earth.

Blends of polyblend and bitumen,when used,help to increase road life by a factor of three. What is the reason?

What happens when sewage is discharged into a river?

$A$ 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?

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