Due to increase in concentration of greenhouse gases, global atmosphere is warming. Assertion is true. Ozone layer in stratosphere acts as shield that protect earth's surface from UV radiation. Depletion in ozone layer resulted in UV radiation reaching the earth. Reason is true. Reason is not correct explanation to assertion as UV radiation reaching earth's surface is not resulting in global warming. Answer : (b)

Hydrocarbon Removal filters are designed to remove hydrocarbons and sediment contaminants from groundwater accumulation in bunded areas, outfalls or as part of any pollution preventative drainage solution on your site, where hydrocarbon risk entering the environment. Answer : (c)

In Delhi, industry and residential activities contribute to 80 per cent of total PM2.5. But the worst-hit cities are Kanpur, Faridabad, Varanasi and Gaya. Reducing residential emission from solid fuels combustion and enforcing new emission standards for power sector can lower PM2.5 levels. The implementation of emission standards for thermal power plants can avoid 124,000 premature deaths every year, according to a recent study. Similarly, cancelling proposed coal-fired power plants can avoid a further 26,000 premature deaths. Answer : (a)

To control air pollution entire fleet of public transport i.e. buses were switched from diesel to compressed natural gas (CNG). All the buses of Delhi were converted to run on CNG by the end of 2002 buses were asked to run on unleaded petrol by the end of 2002 electrostatic precipitator can remove over 99 per cent particulate matter present in the exhaust from a thermal power plant. It has electrode wires that are maintained at several thousand volts, which produce a corona that releases electrons. These electrons attach to dust particles giving them a net negative charge. The collecting plates are grounded and attract the charged dust particles. The velocity of air between the plates must be low enough to allow the dust to fall. BOD is a measure of the amount of oxygen required to remove waste organic matter from water in the process of decomposition by aerobic bacteria. BOD is used, often in wastewater-treatment plants, as an index of the degree of organic pollution in water. Answer : (a)

The high altitude supersonic aircraft flying in stratosphere zone emit nitrous oxides which can destroy ozone significant quantity being highly reactive. Aerosols may be referred to the spray cans that release chlorofluorocarbons which cause the breakdown of ozone Into oxygen once these compound reach the stratosphere. Answer : (b)

CFCs discharged in the lower part of atmosphere move upward and reach stratosphere. In stratosphere, UV rays act on them releasing Cl atoms. Cl degrades ozone releasing molecular oxygen, with these atoms acting merely as catalysts; Cl atoms are not consumed in the reaction. Answer : (b)

Green Muffler is a technique of reducing noise pollution by planting 4-6 rows around the populated areas or noisy places like along roadsides, industrial areas, societies near highways, etc. so that dense trees reduce noise pollution as they filter out the noise and obstruct it reaching the citizens. Answer : (c)

Carbon dioxide contributes 60% to global warming. Methane contributes 20% to global warming. CFC contributes 14% to global warming. N2O contributes 6% to global warming. Answer : (b)

Answer : (b)

Non-biodegradable pollutant persist in environment for long time and has adverse effects for many years Answer : (d)

Approximately 70% of acid rain is a result of dissolved sulfur dioxide (SO2), which forms sulphuric acid. The remaining 30% or so comes from various nitrogen oxides (mostly NO2 and NO3, which has collectedly called NOx). There are also a small percentage of hydrochloric acid and carbonic acid. Answer : (d)

As of April 2019, the average monthly level of CO2 in Earth's atmosphere exceeded 413 parts per million. Answer : (d)

Sound is measured in decibels (dB). A whisper is about 30 dB, normal conversation is about 60 dB, and a motorcycle engine running is about 95 dB. Noise above 70 dB over a prolonged period of time may start to damage your hearing. Loud noise above 120 dB can cause immediate harm to your ears. Answer : (b)

Ozone gas is continuously formed by the action of UV rays on molecular oxygen, and also degraded into molecular oxygen in the stratosphere. There should be a balance between production and degradation of ozone in the stratosphere. Answer : (c)

Exposure to air pollution has many substantial adverse effects on human health. Subjects with chronic respiratory diseases such as chronic obstructive pulmonary disease (COPD) and asthma are especially vulnerable to the detrimental effects of air pollutants. eing exposed to tobacco smoke, air pollution, dusts, vapors, and fumes can also cause acute bronchitis. Answer : (d)

Some of the effects of pollution include leaf damage, slower growth, root damage, and inability to photosynthesize properly. Chlorophyll is important for photosynthesis. Answer : (d)

Carbon dioxide has 200 times more affinity to haemoglobin than oxygen. Answer : (d)

Assertion is correct as suspended particulate matter (SPM) is an important pollutant released by diesel vehicles. Particulate matter includes dust, smoke, soot, pollen and soil particles. Catalytic converters, having expensive metals namely platinum-palladium and rhodium as the catalysts, are fitted into automobiles for reducing emission of poisonous gases. As the exhaust passes through the catalytic converter, unburnt hydrocarbons are converted into carbon dioxide and water, and carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas, respectively. Reason is not a correct explanation of assertion. Answer : (b)

Assertion is correct because methane contributes 20% to global warming. Other green house gases like carbon dioxide, CFC N2O contributes 60%, 14% and 6% to global warming respectively. Efficient engine such as multipoint fuel injection engine can reduce the unburnt hydrocarbon in auto-emissions. It has reduced methane in exhaust. Reason is correct. Reason is not explanation to assertion as both the statement are not related to each other. even though multipoint fuel injection engines reduces methane content, it does not have significant effect on methane contribution to global warming. Answer : (b)

Atomic blast radiate radioactive substance which have adverse effect on land, water, air and living organism. Banning them will reduce pollution. Use of electrically operated autombiles instead of fossil fuel run automobiles will reduce pollution as combustion of fossil fuel release pollutants like oxides of nitrogen and sulphur inot the air. Sewage treatment plant will segregate waste and pollutant from water, thus controlling water pollution. Answer : (d)

Photochemical smog is a mixture of air pollutants which have been chemically altered into further noxious compounds by exposure to sunlight. The main components of photochemical smog are nitrogen oxides, Volatile Organic Compounds (VOCs), tropospheric ozone, and PAN (peroxyacytyl nitrate). Answer : (a)

Biomagnification refers to increase in concentration of the toxicant at successive trophic levels. Secondary consumers comes at highest position in trophic level. So biomagnification will be highest in secondary consumers. Answer : (b)

Sound is measured in decibels (dB). A whisper is about 30 dB, normal conversation is about 60 dB, and a motorcycle engine running is about 95 dB. Noise above 80 dB over a prolonged period of time may start to damage your hearing. Loud noise above 120 dB can cause immediate harm to your ears. Answer : (d)

A lake near a village suffered heavy mortality of fishes within a few days, because lots of urea and phosphate fertilizer were used in the crops in the vicinity and the area was sprayed with DDT by an aircraft. Inorganic phosphorus and nitrogen are responsible for the growth of algae. In polluted water these increase due to which algae increase greatly at the surface of water forming water bloom. Due to death of these/algae their organic matter gets decomposed due to which oxygen gets depleted and aquatic animals die. Answer : (a)

the concentration of DDT is increased at successive trophic levels; say if it starts at 0.003 ppb (ppb = parts per billion) in water, it can ultimately reach 25 ppm (ppm = parts per million) in fish-eating birds, through biomagnification. Answer : (b)

the average temperature at surface of Earth is 15°C. Formaldehyde is carcinogenic to humans based on higher risks of nasopharyngeal cancer and leukemia. Short-term exposure of sulphur dioxide may cause long-term respiratory effects. Nitrogen dioxide is a reddish-brown gas with a pungent, irritating odour and is a prominent air pollutant. Answer : (d)

DDT persists in environment. It remains in active form for 22-25 years. thus, it is non-biodegradable pollutant. Answer : (b)

tai-itai disease was the name given to the mass cadmium poisoning of Toyama Prefecture, Japan, starting around 1912. The term "itai-itai disease" was coined by locals for the severe pains people with the condition felt in the spine and joints. Answer : (d)

The concentration of lead in blood averages about 25 μg /100 mL. Increase to 70 μg /100 mL is generally associated with clinical symptoms. Hence, a level of 30μg/100mL is considered alarming. The chief sources of Pb to water are the effluents of lead and lead processing industries. Answer : (d)

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. Answer : (a)