Air Pollution and Its Control Questions and Answers

Answer: A

The pollutants monitored at every location are sulphur dioxide, nitrogen dioxide, PM10 and PM2.5.

Under the National Air Quality Monitoring Programme run by the Central Pollution Control Board, four pollutants are identified for regular monitoring at all stations: SO2, NO2, respirable suspended particulate matter (PM10) and fine particulate matter (PM2.5). Other parameters such as carbon monoxide, ozone and ammonia are measured only at some stations.

Options B and C include CO, which is not monitored at every location, and option D adds oxygen difluoride, which is not a monitored ambient air pollutant at all.

Answer: C

The key's answer is Burning coal.

Coal burned indoors in stoves and chulhas releases carbon monoxide, sulphur dioxide, nitrogen oxides, fine particulate matter and toxic compounds such as polycyclic aromatic hydrocarbons and arsenic or fluorine from some coals. Solid fuel burning is a leading cause of household air pollution in India.

Room sprays and mosquito coils do release irritants and particles, but in small amounts for short periods. Cooking gas (LPG) is a clean fuel compared with coal, which is why replacing solid fuels with LPG is the aim of schemes like Ujjwala.

Answer: B

The major cause of ozone depletion is CFCs (chlorofluorocarbons).

CFCs released from refrigerants, aerosols and foams rise into the stratosphere, where ultraviolet light breaks them apart and frees chlorine atoms. Each chlorine atom can destroy thousands of ozone molecules, which led to the Antarctic ozone hole and to the Montreal Protocol of 1987.

Carbon dioxide is a greenhouse gas, oxygen is the raw material from which ozone forms, and the last option is not a stable atmospheric gas.

Answer: B

The primary cause of acid rain is sulfur dioxide and nitrogen oxides.

Sulfur dioxide from burning coal and oil, and nitrogen oxides from vehicles and power plants, react with water and oxygen in the atmosphere to form sulfuric and nitric acids, which fall as acid rain.

Carbon dioxide makes rain only slightly acidic (pH about 5.6), which is normal; methane and ozone are not the cause of acid rain.

Answer: C

Statements A and B are correct, so the answer is A and B only.

SAFAR, the System of Air Quality and Weather Forecasting And Research, is an advanced system that forecasts air quality and weather for Indian cities (A). It was developed indigenously by the Indian Institute of Tropical Meteorology, Pune, under the Ministry of Earth Sciences (B).

Statement C is false: SAFAR does measure and report the ultraviolet index along with pollutants such as PM2.5 and PM10, so options including C are wrong.

Answer: C

The gas not considered is nitrogen.

India's National Air Quality Index uses eight pollutants: PM10, PM2.5, nitrogen dioxide, sulphur dioxide, carbon monoxide, ozone, ammonia and lead.

Sulphur dioxide, oxides of nitrogen and carbon monoxide are all measured. Nitrogen gas, which makes up about 78 percent of the air, is harmless and is not a pollutant, so it is not part of the index.

Answer: C

The secondary pollutant is ozone (\(\mathrm{O_{3}}\)).

A primary pollutant is emitted directly from a source; a secondary pollutant forms in the atmosphere by reactions among primary pollutants. Ground-level ozone is produced when nitrogen oxides and volatile organic compounds react in sunlight, as in photochemical smog.

Carbon dioxide, carbon monoxide and methane are all released directly from combustion, decay or other sources, so they are primary pollutants.

Answer: A

Lichens are bioindicators of sulphur dioxide.

Lichens absorb water and dissolved substances directly from the air over their whole surface and have no means of excreting them. Sulphur dioxide damages their algal partner's chlorophyll, so lichens disappear from areas with SO2 pollution, and the variety of lichens present is used to map SO2 levels.

Carbon dioxide is used by the algal partner in photosynthesis, and lichens are not used as indicators of carbon monoxide or fluorine.

Answer: A

The Chernobyl tragedy was related to radioactive radiation.

On 26 April 1986 a reactor at the Chernobyl nuclear power plant in the then Soviet Union (now Ukraine) exploded during a safety test, releasing large amounts of radioactive material over Europe. The harm came from radiation exposure and contamination.

It was not a nuclear weapon (atomic) explosion, though a steam explosion destroyed the reactor, and it was not caused by an earthquake or a volcano.

Answer: A

Incomplete combustion of carbon fuels releases CO.

When there is not enough oxygen, carbon burns only partly: 2C + O₂ → 2CO. Carbon monoxide is a poisonous gas because it binds to haemoglobin far more strongly than oxygen.

CO₂ is the product of complete combustion. Methane is a fuel or a product of anaerobic decay, not of incomplete burning, and SO₄ is a sulphate ion, not a gas from burning carbon fuels.