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Right answer is (c) HAZARDOUS CHEMICAL synthesis

To explain: Synthetic methods should avoid using or generating substances TOXIC to humans and/or the ENVIRONMENT. Hence LESS hazardous chemical synthesis is an important principle.

Right choice is (c) BIODEGRADABLE

The explanation: Biodegradable wastes are deposited in landfills and are converted into COMPOST. These wastes MIX with the SOIL and produce manure. Examples include paper, leaves and vegetable PEELS.

The correct answer is (c) Green fuel

To elaborate: Fuel obtained from plastic waste has high OCTANE rating. It contains no LEAD and, therefore, is known as green fuel. Due to recent developments MADE in chemical and TEXTILE industries, clothes will be made from recycled plastic waste. These will be AVAILABLE soon in the global textile market.

The correct answer is (b) Improper waste disposal

Explanation: Disposing of waste has huge environmental impacts as a CERTAIN type of wastecan be HAZARDOUS and can CONTAMINATE the environment if not handled properly. Some waste GENERATES methane gas, which contributes to the greenhouse EFFECT.

Right choice is (a) Staphylococcus aureus

Best explanation: Staphylococcus aureus is not found in HUMAN excreta. It is a round-shaped BACTERIUM that is a member of the Firmicutes. It is mainly found on the upper respiratory tract and/or on SKIN. But they can also spread through the BLOODSTREAM and INFECT distant organs. Infections caused due to this bacterium can be transferred through the air, skin contact, etc.

The correct answer is (b) False

The EXPLANATION: Plants do not ALWAYS take in carbon dioxide and release oxygen. Plants take in carbon dioxide during the day for the process of PHOTOSYNTHESIS and release oxygen into the atmosphere. But at NIGHT, photosynthesis does not occur, due to the absence of sunlight, and therefore plants take in oxygen for breathing and GIVE out carbon dioxide.

The correct answer is (a) Steel PLANTS

Best explanation: Industries MANUFACTURING aluminum, zinc and copper produce mud and tailings. So, that leaves the answer, i.e., steel plants. Tailings are the by-products LEFT over from MINING and EXTRACTING resources, such as extracting bitumen from oil sands or minerals such as copper or gold from ores.

The CORRECT choice is (a) Nitrogen

For explanation: The irritant red haze in traffic and congested paces is due to the oxides of nitrogen. Haze can REFER to aerosols of the wet type that causes reduction in visibility. Nitrogen GAS is abundantly FOUND in the atmosphere. This nitrogen will combine with oxygen which is also present in the atmosphere and form nitrogen dioxide. Nitrogen gas has a deep red color. Now, nitrogen dioxide will combine with the aerosols and thus, form the red haze that occur in traffic and congested places.

Right choice is (d) Discharge from food processing FACTORIES

To explain: ORGANIC wastes, also known as biodegradable wastes, are natural wastes of PLANTS and animals. The source of organic wastes include DOMESTIC sewage, animal excreta and waste, decaying animals and plants, as WELL as discharge from food processing factories. They can ultimately lead to harm when they use up the oxygen in the water body that they are dumped into.

Right choice is (a) Peroxyacetyl nitrate

The BEST explanation: The full form of PAN is peroxyacetyl nitrate. It is a secondary pollutant present in PHOTOCHEMICAL smog and is unstable. They dissolve more easily in WATER than in ozone. It has a chemical formula of C2H3NO5 and a boiling POINT of 105°C. PAN is formed by oxidation of non-methane volatile organic compounds.

Correct ANSWER is (b) Point source

For explanation: Easily identified source or PLACE of pollution is called as point source. The examples of point sources are municipal and industrial discharge PIPES where the pollutants enter the water-source as treated wastewater. A point source has a NEGLIGIBLE extent, distinguishing it from other pollution source geometries.

Right CHOICE is (a) LIQUIFIED carbondioxide

Explanation: When compared to conventional SOLVENTS, liquified CO2 leaves a LOWER amount of residue. It is also a non-toxic and attractive solvent for temperature-sensitive materials.

The correct choice is (c) Release of CFC

For explanation: CHLOROFLUOROCARBONS (CFCs), also known as freons, are the major reason for depletion of the protective OZONE layer which protects us from the harmful UV radiations, which can be hazardous to human beings and other living organisms. Exposure to UV radiations can cause skin CANCER in humans. CFCs, when they reach the stratosphere, will be broken down into free RADICALS by the UV radiations to liberate chlorine free radical. This chlorine free radical will combine with the stratospheric ozone to form chlorine monoxide and molecular oxygen. In this WAY, the ozone gets used up and there will be lack of ozone available for protection against UV radiations. Thus, ozone gets depleted.

Correct choice is (b) False

Best explanation: PESTICIDES and herbicides represent only a very small PORTION of the WIDESPREAD CHEMICAL pollution. A large number of other COMPOUNDS that are used regularly in chemical and industrial processes for manufacturing activities are finally released into the atmosphere in one or another form.

The correct CHOICE is (a) True

The EXPLANATION is: As we go up the food chain, the concentration of pollutant increases. This process is called biomagnification. This process refers to the BUILDUP of TOXINS in the food chain. At each trophic level, the pollutant gets 10 times more concentrated. Therefore, the animals near the TOP of the food chain gets the most affected by the toxins.

The correct option is (b) During volcanic eruptions

The explanation is: Volcanic eruptions PRODUCE carbon dioxide. The GAS is released either during eruptions or through underground MAGMA. Carbon dioxide through underground magma is released through vents, porous ROCKS, etc. that feeds volcanic lakes. Due to the production of significant amounts of carbon dioxide, volcanoes also contribute to GLOBAL warming.

The correct CHOICE is (b) False

Easy EXPLANATION: Dumping of sewer SLUDGE into land is preferred. This is because it contains COMPOUNDS of nitrogen and phosphorus which act as a good fertilizer for the soil.

Correct choice is (b) Thermal power plant

For explanation I WOULD say: Thermal power plants produce fly ash. Fly ash contains PARTICLES of silica, alumina, and oxides of iron, calcium, and magnesium, and toxic HEAVY metals like LEAD, cobalt, arsenic, and copper. The thermal power plants in INDIA use bituminous coal and produce large quantities of ash.

Right choice is (a) Hydrogen PEROXIDE

Best explanation: Hydrogen peroxide can EASILY breakdown into WATER and oxygen. It is a good oxidizing agent and a strong bleaching agent. USE of H2O2 gives better results and makes use of a lesser amount of water.

The correct answer is (c) They are less persistent

The best explanation: Carbamates are less persistent and more biodegradable PRODUCTS. They were introduced in response to high persistence of chlorinated organic toxins. But these CHEMICALS are SEVERE NERVE toxins and hence more HARMFUL to humans. Insects have become resistant to these insecticides also.

The correct answer is (d) DDT

To elaborate: During World War II, DDT was found to be of great use in the control of malaria and other insect-borne DISEASES. Therefore, after the war, DDT was put to use in AGRICULTURE to control the damages caused by insects, rodents, weeds, and various crop diseases. However, DUE to adverse effects, its use has been BANNED in India.

The CORRECT option is (a) True

To explain: Carbon monoxide (CO) is highly poisonous has a high affinity for haemoglobin. It binds with haemoglobin to FORM carboxyhaemoglobin, which is about 300 TIMES more stable than the oxygen-haemoglobin complex. In blood, when the concentration of carboxyhaemoglobin reaches about 3-4 per CENT, the oxygen carrying capacity of blood is greatly reduced. This oxygen deficiency, results in headache, weak eyesight, NERVOUSNESS, and cardiovascular disorder.

The correct option is (c) Hydrogen sulphide

The best EXPLANATION: Hydrogen sulphide is not an ORGANIC toxin. It is an inorganic toxin. It exists in the gas phase at ambient temperatures, if finely DIVIDED or has a high vapor PRESSURE. But, hydrogen sulphide, becomes far less toxic, when oxidized. Aldrin, Dieldrin, and Toxaphene are organic TOXINS.

Right CHOICE is (B) Dry, warm

To explain I would say: Photochemical smog occurs in warm, dry, and sunny climate. The main components of the photochemical smog results from the ACTION of SUNLIGHT on unsaturated hydrocarbons and nitrogen oxides produced by AUTOMOBILES and factories.

The correct option is (d) Increase in the MOISTURE content of soil

The EXPLANATION: Ozone DEPLETION leads to increase in the evaporation of surface water through the stomata of the leaves and decreases the moisture content of the soil. In addition to this, plant proteins get EASILY affected by UV RADIATIONS and therefore, leads to harmful mutation of cells. Thus, ozone depletion has adverse effects on plant life.

Correct ANSWER is (d) Nitrate ion

Easy explanation: Blue baby SYNDROME (methemoglobinemia) is a disease that is caused when the baby consumes drinking water which is rich in NITRATES. It is caused when the maximum LIMIT of nitrate in water, i.e. 50ppm, is crossed. When the baby drinks nitrate-rich water, then the nitrates get converted to nitrites and this will go and bind with the haemoglobin present in the blood, forming methemoglobin, which does not have the ability to carry oxygen. This is the reason for the blue color of the skin of the baby.

The correct choice is (b) False

Best explanation: Halogenated solvents contaminate groundwater. Whereas liquified CO2 LEAVES a LOWER amount of RESIDUE. It is also a non-toxic and attractive solvent for temperature-sensitive materials.

Correct choice is (d) NUTRIENT enrichment

To explain I would say: Addition of phosphate fertilizers into water bodies LEAD to nutrient enrichment. This condition is also known as EUTROPHICATION. When excess nutrients are formed, this, in turn, will lead to the growth of algae in the water body. These algae will consume the oxygen that is present in the water and thus, there will not be SUFFICIENT oxygen left for use of the aquatic organisms inhabiting the water body. As a result, death of these aquatic organisms will take PLACE in large quantities. And therefore, leads to pollution.

The correct choice is (b) South pole

The best I can explain: In the 1980s, depletion of OZONE layer, known as ozone hole, over the South Pole. In the summer season, NO2 and CH4 react with CHLORINE monoxide and chlorine atoms forming chlorine sinks, PREVENTING much ozone depletion. In winter season, special clouds called POLAR stratospheric clouds are FORMED over Antarctica.

The correct choice is (B) HERBICIDES

The BEST explanation: These DAYS, the pesticide industry has shifted its attention to herbicides. During the first half of the last century, this shift from mechanical to chemical weed control had provided the industry with flourishing economic market.

Correct answer is (C) Cellulose

The EXPLANATION: Cellulose is an organic material derived from PLANTS. Hence they are degraded in nature by microorganisms. They are DEPOSITED in landfills and are converted into compost.

Right option is (a) insoluble, non-biodegradable

Easy explanation: Organic TOXINS are poisonous substances derived from living organisms. Most of the organic toxins are WATER insoluble and non-biodegradable. These high persistent toxins are, therefore, transferred from lower trophic LEVEL to higher trophic level through food chain. Organic toxins are almost equally HARMFUL as the SYNTHETIC chemicals to humans.

Correct option is (b) NICOTINE

The explanation is: PRIOR to World War II, MANY naturally occurring chemicals such as nicotine were used as pest controlling substances for major crops in agricultural practices. This was achieved by planting tobacco PLANTS in the crop FIELDS.

The correct answer is (a) Moulds

Easiest explanation: Moulds is an example of VIABLE pollutant. These are in the category of minute living organisms DISPERSED in the atmosphere. These can LEAD to plant diseases. They can also turn out to be allergic to human BEINGS. Changes in temperature or increase in humidity can cause the DEVELOPMENT of moulds.

Right choice is (b) Fluorine

The best I can explain: Fluorine is not a CONSTITUENT of DDT. DDT is dichlorodiphenyltrichloroethane which has a chemical formula of C14H9Cl5. THEREFORE, DDT does not CONTAIN fluorine, which is evident from the chemical formula. It also contains impurities in small quantities, i.e., about 15% of its composition. The major COMPONENT which comprises of 77% of the substance is its PARA isomer.

The correct answer is (b) Reduction in SOIL PRODUCTIVITY due to soil erosion

Explanation: Negative soil pollution is caused due to the OVERUSE of soil and also due to soil erosion, and THEREBY, LEADING to decrease in soil productivity and efficiency. The other factors that can contribute to negative soil erosion are developmental activities, overgrazing, etc.

Right choice is (a) True

The EXPLANATION: For DRINKING purposes, water should be tested for fluoride ion concentrations. Its deficiency in drinking water is harmful to man and CAUSES diseases such as tooth decay. But, if present in higher concentrations, it causes brown mottling of teeth. It can also lead to harmful EFFECTS in BONES.

Correct option is (b) Polychlorinated biphenyls

Best EXPLANATION: The full form of PCB is Polychlorinated biphenyls. It is used as a cleansing solvent. PCBs are also suspected to be carcinogenic (can lead to cancer). BACTERIA responsible for degrading BIODEGRADABLE detergent feed on these and grow RAPIDLY. While growing, they use up all the oxygen dissolved in water. Thus, the lack of oxygen kills all other forms of aquatic life such as FISH and plants.

Right choice is (b) OXIDATION of ETHENE with an ionic catalyst

Explanation: ETHANAL can be prepared by oxidation of ethene, in the presence of an ionic catalyst in an aqueous medium. This is a GREENER METHOD and gives 90% of yield.

Correct option is (d) Acrolein

Explanation: Acrolein is a colorless, clear liquid with a PUNGENT, SUFFOCATING ODOR. It is a toxic gas, to which if exposed, can cause severe irritations in the EYE, skin, and also causes respiratory tract irritations. Acrolein is highly flammable and PRODUCES toxic concentrations at room temperature.