Fill in the blanks:
$(1)$ The substance that spreads pollution is called .......
$(2)$ The full form of $DDT$ is .......
$(3)$ The area from $10 \ km$ to $50 \ km$ above sea level is called .........
$(4)$ Harmful ultraviolet radiation from the sun reaching the earth is blocked by .....

Cataract and skin cancer are caused by

Biochemical oxygen demand $(BOD)$ value can be a measure of water pollution caused by organic matter. Which of the following statements is correct?

The highest quantity present in the atmosphere is of

Assertion : Ozone is destroyed by $CFCs$ in the upper stratosphere. Reason : Ozone holes increase the amount of $UV$ radiation reaching the earth.

Observe the following statements:
Statement-$I$: The carbon-containing components of photochemical smog are acrolein,methanal,and $PAN$.
Statement-$II$: The number of greenhouse gases in the list given below is $5$: $CH_4, CO_2, NO, H_2O_{(l)}, H_2O_{(g)}, O_2, O_3$.
The correct answer is: