Aerosols are chlorofluoro-hydrocarbon compounds released into air with force in the form of vapour. Main source of aerosols is the emission of jet planes, where fluorocarbons are used. Answer : (b)

In industrial areas, the permissible limit is 75 dB for daytime and 70 dB at night. In commercial areas, it is 65 dB and 55 dB while in residential areas it is 55 dB and 45 dB during daytime and night respectively. Maximum noise limit is 75 dB Answer : (a)

Lichens also absorb sulphur dioxide dissolved in water. Lichens are widely used as environmental indicators or bio-indicators. If air is very badly polluted with sulphur dioxide there may be no lichens present, just green algae may be found. If the air is clean, shrubby, hairy and leafy lichens become abundant. Answer : (a)

Carboxyhemoglobin is a stable complex of carbon monoxide and hemoglobin (Hb) that forms in red blood cells. Large quantities of CO hinder the ability of Hb to deliver oxygen to the body, because carboxyhemoglobin forms more readily than does oxyhemoglobin (HbO2). Carbon monoxide binds to hemoglobin at the same sites as oxygen, but approximately 200 times more tightly. Answer : (d)

The formation of photochemical smog involves three primary ingredients: nitrogen oxides, hydrocarbons and sunlight Besides ozone, photochemical smog contains a number of other pollutants, including:Peroxyacetyl nitrate (PAN) Nitrous acid (HNO2) Nitric acid (HNO3) Answer : (b)

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. So the assertion is correct. During biodegradation of organic compounds, carbon dioxide is released if degradation occurs in presence of oxygen while methane is released if degradation occurs in absence of oxygen. So reason is false Answer : (c)

World Environment Day is celebrated on 5 June every year, and is the United Nations' principal vehicle for encouraging awareness and action for the protection of the environment. Answer : (b)

arsenic is inevitably absorbed into the blood stream. Arsenic in cells clearly stimulates the production of hydrogen peroxide (H2O2). When the H2O2 reacts with certain metals such as iron or manganese it produces a highly reactive hydroxyl radical. Iron is present haemoglobin of RBC which result in degradation of RBC. Answer : (d)

DDT is a persistent organic pollutant that is readily adsorbed to soils and sediments, which can act both as sinks and as long-term sources of exposure affecting organisms. Depending on conditions, its soil half-life can range from 22 days to 30 years. It is not easily degraded. Its breakdown products and metabolites, DDE and DDD, are also persistent and have similar chemical and physical propertie Answer : (c)

There are three main stages of the wastewater treatment process, aptly known as primary, secondary and tertiary water treatment. Primary treatment : These treatment steps basically involve physical removal of particles – large and small – from the sewage through filtration and sedimentation. Secondary treatment of wastewater works on a deeper level than primary and is designed to substantially degrade the biological content of the waste through aerobic biological processes The aim of tertiary wastewater treatment is to raise the quality of the water to domestic and industrial standards, or to meet specific requirements around the safe discharge of water. In the case of water treated by municipalities, tertiary treatment also involves the removal of pathogens, which ensures that water is safe for drinking purposes. Answer : (b)

Chlorofluorocarbons (CFCs) are anthropogenic compounds that have been released into the atmosphere since the 1930s in various applications such as in air-conditioning, refrigeration, blowing agents in foams, insulations and packing materials, propellants in aerosol cans, and as solvents. Answer : (c)

Exposure to prolonged or excessive noise has been shown to cause a range of health problems ranging from stress, poor concentration, productivity losses in the workplace, and communication difficulties and fatigue from lack of sleep, to more serious issues such as cardiovascular disease, cognitive impairment, tinnitus and hearing loss. Roadway noise levels are sufficient to constrict arterial blood flow and lead to elevated blood pressure. Answer : (d)

Chlorination is the process of adding chlorine to drinking water to disinfect it and kill germs. Ozone is a powerful oxidising agent which, when dissolved in water, produces a broad spectrum biocide that destroys all bacteria, viruses and cysts. Chloramines (also known as secondary disinfection) are disinfectants used to treat drinking water. Answer : (d)

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 : (c)

a region of marked thinning of the ozone layer in high latitudes i.e. stratosphere chiefly in winter, attributed to the chemical action of CFCs and other atmospheric pollutants. The resulting increase in ultraviolet light at ground level gives rise to an increased risk of skin cancer. Answer : (b)

Phosphate is an water pollutant which leads to eutrophication. Hydrocarbons, sulphur dioxide are air pollutant which causes smog and acid rain respectively. Pollen grain is generally not characterised as air pollutant, but many people are allergic to pollen and so can be considered as air pollutant. Answer : (a)

Excessive use of fertilizers will lead in run-off of fertilizers by rain in water bodies like lakes, ponds. This continuous supply of nutrient will result in eutrophication. Thus indiscriminate use of fertilizers is water pollution. Answer : (b)

A whisper is about 30 dB, normal conversation is about 60 dB Answer : (b)

Chloroflurocarbons (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 : (c)

Answer : (c)

SO2 inhibits photosynthesis by disrupting the photosynthetic mechanism. The opening of the stomata is promoted by sulfur dioxide, resulting in an excessive loss of water. With the increase in SO2 concentration, lamina curling was observed to be associated with drying and developing brittleness Answer : (d)

Methanogenic bacteria is present in rumen of cattle. When cattle consumes cellulosic material, these bacteria help in the breakdown of cellulose. Methane is also released. Methane is a greenhouse gas. Answer : (a)

Environment Protection Act, 1986 is an “umbrella” legislation designed to provide a framework for central government coordination of the activities of various central and state authorities established under previous laws, such as the Water Act and the Air Act. Answer : (b)

Treatment of waste water is done by the heterotrophic microbes naturally present in the sewage. This treatment is carried out in two stages: Primary treatment : These treatment steps basically involve physical removal of particles – large and small – from the sewage through filtration and sedimentation. The effluent from the primary settling tank is taken for secondary treatment. Secondary treatment or Biological treatment : The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh like structures). While growing, these microbes consume the major part of the organic matter in the effluent and purifies water. Answer : (a)

The allethrins are a group of related synthetic compounds used in insecticides. They are synthetic pyrethroids, a synthetic form of a chemical found naturally in the chrysanthemum flower. Answer : (d)

exposure to arsenic via drinking-water has been shown to cause a severe disease of the blood vessels, which leads to gangrene, known as 'black foot disease'. Answer : (d)

The USA is mainly responsible for the emission of chlorofluorocarbons, which made it contribute greatly to the formation of a hole in the ozone layer. Answer : (a)

The Government of India through a new auto fuel policy has laid out a roadmap to cut down vehicular pollution in Indian cities. More stringent norms for fuels means steadily reducing the sulphur and aromatic content in petrol and diesel fuels. Euro III norms, for example, stipulate that sulphur be controlled at 350 parts-per-million (ppm) in diesel and 150 ppm in petrol. Aromatic hydrocarbons are to be contained at 42 per cent of the concerned fuel. The goal, according to the roadmap, is to reduce sulphur to 50 ppm in petrol and diesel and bring down the level to 35 per cent. Corresponding to the fuel, vehicle engines will also need to be upgraded. Answer : (c)

Heated (thermal) wastewaters flowing out of electricity-generating units,e.g., thermal power plants, constitute another important category of pollutants. Thermal wastewater eliminates or reduces the number of organisms sensitive to high temperature, and may enhance the growth of plants and fish in extremely cold areas but, only after causing damage to the indigenous flora and fauna. About 75 to 82 percent of thermal pollution is generated by power plants. Answer : (b)

Third generation pesticides are chemicals, called juvenile hormones, are made in two small glands in insects' heads. Juvenile hormone must be secreted at certain stages in an insect's life and not secreted at other times. Answer : (b)