Question

Match the following and choose the correct combination from the options given.

	Column I		Column II
A	DDT	1	NO${}_x$, CO${}_2$
B	PAN	2	Smog
C	Acid rain	3	Biological magnification
D	Global warming	4	SO${}_2$

• A. A- 4, B- 3, C- 2, D- 1
• B. A- 1, B- 3, C- 2, D- 4
• C. A- 2, B- 3, C- 4, D- 1
• D. A- 3, B- 2, C- 4, D- 1

Answer 1

The correct option is D A- 3, B- 2, C- 4, D- 1

Biomagnification refers to increase in concentration of the toxicant at successive trophic levels. This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted, and is thus passed on to the next higher trophic level. This phenomenon is well known for mercury and DDT.

Pollutants like nitrogen oxides and volatile organic compounds are called as primary pollutants. Products like ozone, aldehydes, and peroxyacetyl nitrates (PAN) are called secondary pollutants. The mixture of these primary and secondary pollutants forms photochemical smog.

Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.

Global warming is caused by the emission of greenhouse gases. 72% of the totally emitted greenhouse gases is carbon dioxide ($C{O}_2$), 18% Methane and 9% nitrous oxide (NOx). Carbon dioxide emissions therefore are the most important cause of global warming. $C{O}_2$ is created by burning fuels like e.g., oil, natural gas, diesel, organic-diesel, petrol, organic-petrol, ethanol. Thus, the correct answer is option D.