Test: Air pollution - JEE MCQ

London smog is reducing in nature.

Hydrocarbons are not emitted during volcanic eruptions.

In stratosphere the following reactions takes place which are responsible for depletion of ozone layer.
Hence, methane is not responsible for ozone layer depletion.

Acid rain is caused by chemical reaction that begins when compounds like sulphur dioxide (SO₂) and nitrogen dioxide (NO₂) are released into the air. There 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.

CO and oxides of Nitrogen are poisnous gases present in automobile exhaust gases.

UV radiations are absorbed in stratosphere.

The average residence time of NO is 4 days.

Oxides of nitrogen and sulphur are responsible for acid rain.

Due to the presence of HNO₃ and H₂SO₄ (strong acids) rain water becomes acidic and rain is called the acid rain.

Chemical pollutants in photochemical smog are nitrogen oxides (NO and NO₂), volatile organic compounds, ozone (O₃) and peroxyacetyl nitrate.

Air pollution greatly affect the troposphere.

Acid rain contains H₂SO₄ > HNO₃ > HCl.

Greenhouse gases in Earth's atmosphere are water vapour, CO, methane, nitrous oxide and ozone. Thus, nitrogen is not in greenhouse gas.

SO₂ forms a part of photochemical smog.

CFC (Chlorofluorocarbons) are causing depletion of ozone in the stratosphere. This occurs because ultra violet light also causes CFC's to decompose, producing atomic chlorine. The chlorine atoms react with ozone molecules, resulting in a net removal of O₃ molecules from the stratosphere.

Chlorofluoro carbons (CFCs) such as , , hydrofluoro carbons (HFCs) are responsible for ozone layer depletion or ozone holes.

Ozone absorbs U. V. radiations harmful to human life.

Radiation coming from sun or outerspace have high energy or short wavelength, which are allowed to enter by green house gases. However, radiation emitted by earth is in infrared region, having long wavelength, are reflected back by the envelope of green house gases.

Green house gases such as CO₂, ozone, methane, the chlorofluorocarbon compounds and water vapour form a thick cover around the earth which prevents the IR rays emitted by the earth to escape. It gradually leads to increase in temperature of atmosphere.

CO is highly toxic and impairs respiration. CO combines with haemoglobin of blood and reduces its O₂ carrying capacity.