Pollutants that have been emitted from all sources in a region and have had time to mix, diffuse from their peak concentration, and undergo physical, chemical, and photochemical reactions is called regional pollution. Example of regional air pollution are acid rain and smog. Answer : (d)

Presence of large amounts of nutrients in waters also causes excessive growth of planktonic (free-floating) algae, called an algal bloom which imparts a distinct colour to the water bodies. Algal blooms cause deterioration of the water quality and fish mortality. Some bloom-forming algae are extremely toxic to human beings and animals. Assertion and reason both are false. Answer : (d)

The molecules of green house gases radiate heat energy, and a major part of which again comes to Earth’s surface, thus heating it up once again. This cycle is repeated many a times. They are responsible for the greenhouse effect. Increase in the level of greenhouse gases has led to considerable heating of Earth leading to global warming. Answer : (a)

Hydrogen does not cause pollution. Hydrogen is considered as clean energy. Answer : (d)

September 16 was designated by the United Nations General Assembly as the International Day for the Preservation of the Ozone Layer. Answer : (b)

Domestic sewage primarily contains biodegradable organic matter, which readily decomposes because of microorganism. Micro-organisms involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen, and as a result there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge. This causes mortality of fish and other aquatic creatures. Answer : (c)

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 Answer : (d)

Carbon dioxide is a green house gas. Increase in concentration of carbon dioxide and other green house gases in atmosphere leads to increase in temperature of earth's surface. This phenomenon is called global warming. Answer : (c)

Photochemical smog is a mixture of pollutants that are formed when nitrogen oxides and volatile organic compounds (VOCs) react to sunlight, creating a brown haze above cities. It tends to occur more often in summer, because that is when we have the most sunlight. Answer : (d)

Nitrates from polluted drinking water form compounds in the body that change haemoglobin to methemoglobin, decreasing the ability of blood to carry oxygen. This condition is referred to as blue baby syndrome. Answer : (b)

Carbon monoxide has more affinity to haemoglobin than oxygen and binds with the haemoglobin to form the carboxyhaemoglobin. This results in the deficiency of the oxygen in the body called carbon monoxide poisoning methane does not have affinity with haemoglobin. Answer : (b)

Carbon monoxide has more affinity to haemoglobin than oxygen. When carbon monoxide from autombiles combine with haemoglobin forms Carboxyhemoglobin or carboxyhaemoglobin (symbol COHb or HbCO) which is a stable complex. This prevents reaction between and haemoglobin Answer : (d)

Option (a) is not correct because Azotobacter is free living soil microbes that fix atmospheric nnitrogen. It is not present in root nodules of plants. Option (b) is not correct because Cyanobacteria Anabaena and Nostoc have specialized cells known as Heterocyst which help in nitrogen fixation. Option (c) is not correct because maize can be grown without chemical fertilizers. Option (d) is correct because excessive use of chemical fertilizers contaminate water bodies due to runoff of excess water and lead to increased algal growth due to nutrient enrichment of the water bodies. This is known as eutrophication. Answer : (d)

Malathion is an organophosphate insecticide Lindane has been used both as an agricultural insecticide and as a pharmaceutical treatment for lice and scabies. BHC is an insecticide 2,4-D (2,4-Dichlorophenoxyacetic acid) is a systemic herbicide that affects the specifically acts on the dicot weeds. It is used in the crop field of cereals to wipe out the weeds without affecting the monocot cereals. Answer : (d)

almost 40% forest have been lost in the tropics compared to only 1% in the temperate region. The greenhouse effect is a natural phenomenon allowing life to occur on the planet. It is caused by a series of greenhouse gases (water vapor, carbon dioxide, methane and nitrous oxide) that absorb part of the energy, while the remainder escapes into space. Ozone in upper part of atmosphere prevents UV ray from reaching the surface and is not harmful to animal. Eutrophication is when a body of water becomes overly enriched with minerals and nutrients which induce excessive growth of algae. Although eutrophication is commonly caused by human activities, it can also be a natural process, particularly in fresh water bodies like lakes Answer : (c)

CO2 constitutes about 0.041% by volume of the atmosphere. So nearest answer is option (b) Answer : (b)

Biocides are substances or products used to protect against unwanted plants, animals, or microorganisms. When it was introduced in World War II, DDT was effective in reducing malaria morbidity and mortality. It was first biocides used in large scale. Answer : (b)

Lead can be released directly into the air, as suspended particles. Historic major sources of lead air emissions were motor vehicles and industrial sources Answer : (a)

The Montreal Protocol, finalized in 1987, is a global agreement to protect the stratospheric ozone layer by phasing out the production and consumption of ozone-depleting substances (ODS) Answer : (a)

All the option except option (a) are pollutant. CO2 is greenhouse gas. Answer : (a)

Addition of phosphates and nitrates into the water leads to nutrient enrichment. This phenomenon is called eutrophication. Eutrophication induces excessive growth of algae. Option (d) is correct. Answer : (d)

A CO concentration of 12-13000 ppm or 0.1-0.7 mmHg is toxic Answer : (d)

Cutting down on fossil fuels, reducing deforestation and improving efficinecy of energy use will reduce the emission of cabon dioxide and helps in reducing global warming. Cutting trees and increasing growth of human population will increase carbon dioxide concentration. carbon dioxide is a greenhouse gas which result in increase in global warming. Answer : (d)

Answer : (a)

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 (those bacteria that live only in an environment containing oxygen). BOD is used, often in wastewater-treatment plants, as an index of the degree of organic pollution in water. Distilled water has almost no bacteria hence least BOD. next is unpolluted pond water. Highly unpolluted pond water has maximum aerobic bacteria and hence highest BOD Answer : (b)

Usnea is a genus of mostly pale grayish-green fruticose lichens that grow like leafless mini-shrubs or tassels anchored on bark or twigs.Usnea is very sensitive to air pollution, especially sulfur dioxide. Under bad conditions they may grow no larger than a few millimetres, if they survive at all. Where the air is unpolluted, they can grow to 10–20 cm long. Answer : (c)

Bioremediation refers to the use of specific microorganisms to remove any toxic or harmful substances. Species in the bacterial genus Pseudomonas present high potential for hydrocarbon degradation due to their metabolic diversity, their abundance in microbial communities, and their resistance to chemical remediation agents present at contamination sites. Answer : (d)

DDT is very insoluble in water and very persistent (non-biodegradable) in the environment, making it a highly polluting hazard. Answer : (c)

Chlororflurocarbon known as freons are stable, nonflammable, low toxicity gases or liquids which have generally been used as refrigerants and as aerosol propellants. It was used in refrigerators, air conditioners, body sprays, etc. Answer : (a)

A lake receiving domestic sewage indicates high BOD. High BOD means more oxygen will be consumed by bacteria for process of decomposition of organic matter present in domestic sewage. This will result in depletion in oxygen leading to death of fishes. Answer : (c)