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

Ozone in stratosphere, and it acts as a shield absorbing ultraviolet radiation from the sun. UV rays are highly injurious to living organisms since DNA and proteins of living organisms preferentially absorb UV rays, and its high energy breaks the chemical bonds within these molecules.It also cause skin cancer and snow blindness. Ozone depletion result in UV rays reaching earth cause skin cancer and mutation. Answer : (b)

Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochlorine. Answer : (b)

In India, the Air (Prevention and Control of Pollution) Act came into force in 1981, but was amended in 1987 to include noise as an air pollutant. Answer : (b)

The major undesirable components of photochemical smog are nitrogen dioxide (NO2), ozone (O3), PAN (peroxyacetylnitrate), and chemical compounds that contain the –CHO group (aldehydes). Answer : (d)

The thickness of the ozone in a column of air from the ground to the top of the atmosphere is measured in terms of Dobson units (DU). Answer : (d)

the balance of ozone layer has been disrupted due to enhancement of ozone degradation by chlorofluorocarbons (CFCs). CFCs find wide use as refrigerants. 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 : (a)

The major undesirable components of photochemical smog are nitrogen dioxide (NO2), ozone (O3), PAN (peroxyacetylnitrate), and chemical compounds that contain the –CHO group (aldehydes). Answer : (c)

Answer : (d)

Ozone (O3) is a very effective disinfection agent and can be used in swimming pools to replace chlorine and bromine containing disinfection chemicals. Answer : (b)

Eutrophication is the natural aging of a lake by nutrient enrichment of its water. It occurs when a body of water becomes overly enriched with minerals and nutrients which induce excessive growth of algae. This process may result in oxygen depletion of the water body. Answer : (c)

The greenhouse effect can be defined as the capture and re-radiation of the infre-red radiations by the tropospheric gases like ozone, carbon dioxide, water vapours and dust. This lead to the increase in the temperature of the atmosphere, and as a result the over all temperature of the earth increases, causing global warming. Answer : (d)

During combustion or burning, carbon from fossil fuels combine with oxygen in the air to form carbon dioxide and water vapor. Radioactive (or nuclear) waste is a byproduct from nuclear reactors, fuel processing plants, hospitals and research facilities. Radioactive waste is also generated while decommissioning and dismantling nuclear reactors and other nuclear facilities. The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without this atmosphere. It is caused by grrenhouse gases like carbon dioxide, methane etc. Burning either fossil fuels or biomass releases carbon dioxide (CO2), a greenhouse gas. However, the plants that are the source of biomass for energy capture almost the same amount of CO2 through photosynthesis while growing as is released when biomass is burned, which can make biomass a carbon-neutral energy source. Answer : (c)

High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of eggshell and their premature breaking, eventually causing decline in bird populations. Answer : (c)

Environmental protection act was passed in March 1986, it came into force on 19 November 1986. Answer : (a)

Automobiles are a major cause for atmospheric pollution atleast in the metro cities. 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. Motor vehicles equipped with catalytic converter should use unleaded petrol because lead in the petrol inactivates the catalyst. Answer : (a)

The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without this atmosphere. Radiatively active gases in a planet's atmosphere radiate energy in all directions. Water vapor, carbon dioxide, methane, and other trace gases in Earth's atmosphere absorb the longer wavelengths of outgoing infrared radiation from Earth's surface. Answer : (d)

Answer : (c)

Water vapor, carbon dioxide, methane, and other trace gases in Earth's atmosphere absorb the longer wavelengths of outgoing infrared radiation from Earth's surface. Answer : (b)

fabric filter is an air pollution control device and dust collector that removes particulates or gas released from commercial processes out of the air. A scrubber can remove gases like sulphur dioxide. In a scrubber, the exhaust is passed through a spray of water or lime. Arrester are used to separate particulate matter (PM) from contaminated air. Incinerator is the device where waste is burnt e.g. furnace. It converts the waste material into ash, gases, particles and heat. Answer : (a)

he surplus carbon is stored in the plant, helping it to grow. When trees are cut down and burned or allowed to rot, their stored carbon is released into the air as carbon dioxide. And this is how deforestation and forest degradation contribute to global warming. Statement X and Y are correct and statement Y is correct explanation for statement X as increase in green house gas level lead to global warming. Answer : (a)

Developed, industrialized countries made a promise under the Kyoto Protocol to reduce their annual hydrocarbon emissions by an average of 5.2% by the year 2012. Answer : (c)

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)

The central pollution control board prescribed the BOD limit for the discharge of industrial and municipal waste water as < 10 ppm. Answer : (c)

Answer : (b)

Lichen, is sensitive to atmospheric pollutant such as sulphur dioxide, lead and mercury emissions. This sensitivity makes lichen a valuable biological indicator of air quality. Answer : (b)

Most ozone resides in the stratosphere (a layer of the atmosphere between 10 and 40 km above us), where it acts as a shield to protect Earth's surface from the sun's harmful ultraviolet radiation. Answer : (d)

Ozone gas is continuously formed by the action of UV rays on molecular oxygen, and also degraded into molecular oxygen in the stratosphere. Answer : (d)

The United Nations Environment Programme (UNEP) is the leading environmental authority in the United Nations system. UNEP main goals include analysis and assessment of global environment, early warning of environmental threats, elaboration of international environmental legislation for sustainable development, raising public awareness on international environmental policy and activities Answer : (d)

Developing substitutes for chloroflurocarbon will not allow the build of chlorine radical in the atmosphere. Minimal use of nitrogen fertilizers will not allow nitrogen oxides to cause secondary pollutants Limited use of fossil fuels will not add carbon dioxide, methane, oxides of sulphur etc and thus environment can be saved from their deleterious effects. increase use of ACs, refrigerators, production of plastic forms and aerosol spray can propellants are harmful to the environment in a great deal because they cause ozone hole as well as global warming. Answer : (b)