Thinking Process

On the basis of degradation/natural disposal, pollutants may be biodegradable and non-biodegradable. Nature and natural disasters don’t generate non-biodegradable waste.

Answer

(c) Non-biodegradable pollutants have a slow or zero rate of degradation by general biological processes. They include plastics, tin container, heavy metals, radioactive substances, etc. These are created by human activities. like industrilisation.

Biodegradable pollutant are degraded or disposed quickly by biological processes. Some biodegradable pollutant created by human are paper, house hold waste like peel of vegetables, fruits and sewage.

• (a) Nature: Nature does not create non-biodegradable pollutants as these pollutants are typically synthetic or man-made materials that do not break down easily through natural processes.

• (b) Excessive use of resources: While excessive use of resources can lead to pollution, it is not the direct cause of non-biodegradable pollutants. Non-biodegradable pollutants are specifically created through human activities and industrial processes.

• (d) Natural disasters: Natural disasters do not create non-biodegradable pollutants. These pollutants are a result of human activities and are not naturally occurring substances.

Thinking Process

Air pollutants are gaseous material, radioactive substances and particulate matter.

Answer

(a) Particulate air pollutant like soot, flyash, dust of various types, pollens, spores, fur, hair, etc., can be differentiated as setteable $(10 \mu \mathrm{m}$ or more) and suspended, (less than $10 \mu \mathrm{m})$ particulate matter pollutant.

Their effect (on the environment) depends on the size of particles. According to CPCB particulate matter of $2.5 \mu \mathrm{m}$ or less in diameter are responsible for causing great harm to human health. The particular matter of 2.5 or less in size are inhaled deep into the respiratory tract (upto lungs) and causes respiratory problems and may even lead to death.

• (b) 5.00 micrometers: Particulate matter of 5.00 micrometers in diameter is larger than 2.5 micrometers and does not penetrate as deeply into the respiratory tract. Therefore, it is less harmful compared to particles of 2.5 micrometers or less.

• (c) 10.00 micrometers: Particulate matter of 10.00 micrometers in diameter is considered settleable and does not remain suspended in the air for long periods. These larger particles are less likely to be inhaled deeply into the respiratory tract, making them less harmful to human health.

• (d) 7.5 micrometers: Particulate matter of 7.5 micrometers in diameter is also larger than 2.5 micrometers and does not penetrate as deeply into the respiratory tract. Consequently, it is less harmful compared to particles of 2.5 micrometers or less.

Answer

(d) The material generally used for sound proofing of rooms like recording studio, cinema hall, auditorium which absorb sound and facilitate in proofing is styrofoam.

Ear plugs (device used by working person of commercial and industrial zone) are made up of very fine glass wood or cotton wood impregnanted with wax while ear muffs contain fluid seals or plastic foam for absorbing sound.

• Cotton: While cotton can provide some level of sound absorption, it is not as effective as other materials specifically designed for soundproofing. Cotton is more commonly used for insulation and comfort rather than for its acoustic properties.

• Coir: Coir, which is made from coconut husks, is primarily used for making mats, brushes, and other products. It does not have the necessary density or structure to effectively absorb sound and is not commonly used in soundproofing applications.

• Wood: Wood can reflect sound rather than absorb it, making it less effective for soundproofing purposes. While wood can be used in acoustic treatments to manage sound reflections, it is not typically used as the primary material for soundproofing rooms like recording studios or auditoriums.

Answer

(b) Compressed Natural Gas (CNG) is the best and cheap fuel. It has replaced petrol and diesel fuel as it is considered as clean fuel.

CNG consists of around $90 \%$ methane, by compressing it to less than $1 \%$ of volume it occupies at standard atmospheric pressure. Propane and butane together form LPG or liquified petroleum gas while ethane is used in chemical industry to produce ethene.

• Propane and butane together form LPG or liquified petroleum gas.
• Ethane is used in the chemical industry to produce ethene.

Answer

(c) Eichhornia (water hyacinth) has been introduced in India to check water pollution, as this weed absorbs mercury, cadmium, lead and nickel from sewage water.

It is considered as worlds most problematic weed as it is on invasive species. If not controlled, water hyacinth covers the enitre pond or ake and impacts water flow. Blocks sunlight, acts as prime habitat for mosquito (vector) snails host for flatworm and starves water of oxygen.

• Azolla: While Azolla is a fast-growing aquatic fern that can cover water surfaces, it is not considered as problematic as Eichhornia. Azolla is often used in rice paddies for nitrogen fixation and as a biofertilizer, making it beneficial rather than problematic.

• Wolffia: Wolffia, also known as watermeal, is the smallest flowering plant and does not pose significant ecological problems. It does not spread as aggressively as Eichhornia and is often used in wastewater treatment and as animal feed.

• Trapa: Trapa, commonly known as water chestnut, can be invasive in some regions but is not as widespread or problematic as Eichhornia. It is also cultivated for its edible seeds, which makes it economically valuable in certain areas.

Answer

(d) Biomagnification, also called as bioaccumulation is the accumulation of non-biodegradable toxic material like $\mathrm{Hg}$, DDT, etc,, in different trophic levels.

In the process of bioaccumulation, the concentration of non- biodegradable pollulants increases at each successive trophic level of the food chain, thus harming the environment/ecosystem at an alarming rate, whereas $\mathrm{SO}_{2}$ (Isulphur dioxide) is an air pollutant and acts as precursor of acid rain.

• $\mathrm{SO}_{2}$ (Sulphur dioxide) is an air pollutant and acts as a precursor of acid rain, but it does not accumulate in the food chain and therefore does not cause biomagnification.

Answer

(a) The expanded form of DDT is dechloro diphenyl trichloroethane.

It is an insectiside which was first synthesised in 1874. in insects it opens the sodium ion channels in neurons which leads to spas on and eventual death DDT, BHC are organic compound which were effectively used against pest during 1970 and 1980. But, now these are banned due to their less or no degradation.

• (b) dichloro diethyl trichloroethane: This option is incorrect because DDT does not contain an “ethyl” group in its structure. The correct structure includes “diphenyl” groups.

• (c) dichloro dipyrydyl trichloroethane: This option is incorrect because DDT does not contain “dipyrydyl” groups. The correct structure includes “diphenyl” groups.

• (d) dichloro diphenyl tetrachloroacetate: This option is incorrect because DDT does not contain a “tetrachloroacetate” group. The correct structure includes “trichloroethane” as part of its name.

Answer

(c) Out of the given options, bone takes the longest time for biodegradation, whereas cotton, paper and jute can be easily degraded by the action of microbes. Bone is made up of a protein fraction, mineral fraction and organic compounds.

• Cotton: Cotton is a natural fiber that is easily broken down by microbes due to its organic composition, making it biodegradable in a relatively short period of time.
• Paper: Paper is primarily made from wood pulp, which is also an organic material that can be readily decomposed by microorganisms, resulting in a faster biodegradation process.
• Jute: Jute is a plant-based fiber that is highly biodegradable because it is composed of cellulose and lignin, which are easily decomposed by microbial activity.

Answer

(c) Dobson unit is used to express the column on dessity of trace gases e.g., ozone. On the other hand, oxygen sensors are used to measure the exhaust gas concentration of oxygen

• (a) The statement is correct. The Montreal Protocol is indeed associated with the control of emissions of ozone-depleting substances.
• (b) The statement is correct. Methane and carbon dioxide are both greenhouse gases.
• (d) The statement is correct. The use of incinerators is crucial for the disposal of hospital wastes to ensure they are safely and effectively managed.

Answer

(a) Burning coal is the cause of major indoor chemical pollution. It releases carbon content in the atmosphere which combines with oxygen to form carbon dioxide, a threat to environment or may result in the formation of carbon monoxide which is a threat to human health.

Burning of coal also releases inhalable particlen nitrogen oxides sulphur dioxides metal and silicates. Although of mosquito coil and room spray causes indoor chemical pollution but their effects are long term.

• Burning cooking gas: While burning cooking gas does release some pollutants such as carbon monoxide and nitrogen dioxide, the levels are generally lower compared to burning coal. Additionally, modern cooking appliances are designed to minimize emissions, making it a less significant source of indoor chemical pollution.

• Burning mosquito coil: Burning mosquito coils releases smoke that contains various chemicals, including formaldehyde and other volatile organic compounds (VOCs). However, the quantity and impact of these pollutants are generally less severe compared to the pollutants released by burning coal.

• Room spray: Room sprays can release VOCs and other chemicals into the indoor environment, which can contribute to indoor air pollution. However, the concentration and impact of these pollutants are typically lower and less harmful compared to the pollutants released by burning coal.

Answer

(d) The green scum seen in the fresh water bodies mainly consists of green algae and blue-green algae, while the red algae is mostly marine.

• (b) Red algae: Red algae are primarily found in marine environments rather than freshwater bodies. They are not typically responsible for the green scum seen in freshwater.

• (c) Green algae: While green algae do contribute to the green scum in freshwater bodies, this option alone is incomplete because it does not account for the presence of blue-green algae, which also contribute to the scum.

Answer

(d) Relative loudness of sound ranges from $30 \mathrm{~dB}-60 \mathrm{~dB}$ and is generally not hazardous. The loudness above $60-80 \mathrm{~dB}$, is not much uncomfortable while prolonged exposure to noise level above $80 \mathrm{~dB}$ is painful and gradually leads to permanent loss of hearing ability or deafness.

The premissible sound level in different areas is shown in the following table

• (a) $150 \mathrm{~dB}$: This level of loudness is extremely high and can cause immediate physical pain and damage to the ears. It is far beyond the threshold of discomfort and can lead to permanent hearing loss or other serious health issues.

• (b) $215 \mathrm{~dB}$: This level of loudness is not only discomforting but also potentially lethal. Such a high decibel level can cause severe physical harm, including rupturing eardrums and causing other internal injuries. It is far beyond any reasonable level of sound a person can withstand.

• (c) $30 \mathrm{~dB}$: This level of loudness is relatively low and is generally considered to be within the range of normal conversation or a quiet environment. It is not discomforting and is well below the threshold that would cause any harm or discomfort to a person.

Answer

(b) The major source of noise pollution, worldwide is transport system i.e., transport vehicles (both public and private).

Whereas all machines (noise producing) wheather, agricultural or engine of motor, vehicle and machine employed in various industries like textile, printing, sugar, engineering and agricultural implements are also sources of noise pollution.

• Office equipment: While office equipment such as printers, copiers, and computers can contribute to noise pollution in a localized office environment, they do not have a significant impact on noise pollution on a global scale.

• Sugar, textile, and paper industries: These industries do produce noise through their machinery and processes, but their contribution to global noise pollution is relatively limited compared to the widespread and constant noise generated by the transport system.

• Oil refineries and thermal power plants: These facilities do generate noise, particularly from machinery and operational processes, but their impact is more localized to their immediate surroundings and does not contribute as significantly to global noise pollution as the transport system does.

Answer

(a) Environment Protection Act came into force on November 1986, at the birth anniversary of late Prime Minister of India Smt. Indira Gandhi.

Air prevention and central of pollution Act came into force in 1981 which is meant for the preservation of quality air.

Water Act 1974 is meant for restoration of quality of all type of surface and ground water.

In 1987 Amendment of Air Act to include noise came into existance (force).

• Option (b) is incorrect because:

  • The Environment Protection Act was enacted in 1986, not 1974.
  • The Air Prevention and Control of Pollution Act was enacted in 1981, not 1986.
  • The Water Act was enacted in 1974, not 1987.
  • The Amendment of the Air Act to include noise was enacted in 1987, not 1981.

• Option (c) is incorrect because:

  • The Environment Protection Act was enacted in 1986, not 1981.
  • The Air Prevention and Control of Pollution Act was enacted in 1981, not 1974.
  • The Water Act was enacted in 1974, not 1987.
  • The Amendment of the Air Act to include noise was enacted in 1987, not 1986.

• Option (d) is incorrect because:

  • The Water Act was enacted in 1974, not 1987.
  • The Amendment of the Air Act to include noise was enacted in 1987, not 1974.

Answer

(a) Catalytic converters contain costly metals like rhodium and platinum-palladium as catalysts, and when exhaust gas passes to fitted catalytic converter, the unburnt hydrocarbons (cause of cancer) are oxidised into water and carbon dioxide.

• (b) carbon mono oxide: Catalytic converters are designed to reduce harmful emissions, including carbon monoxide. They convert carbon monoxide into less harmful carbon dioxide, not the other way around.

• (c) methane: Catalytic converters do not convert unburnt hydrocarbons into methane. Instead, they oxidize hydrocarbons into carbon dioxide and water.

• (d) carbon dioxide and methane: While catalytic converters do convert unburnt hydrocarbons into carbon dioxide, they do not produce methane in the process. The primary products are carbon dioxide and water.

Answer

(a) Removal of sulphur from petrolium product (diesel) reduces the emission of oxides of sulphur like $SO_{2}$ and $SO_{3}$ in the exhaust fumes.

• (b) Increasing the efficiency of automobile engines is not directly related to the removal of sulphur from petroleum products. Engine efficiency is more influenced by factors such as fuel composition, engine design, and maintenance.

• (c) While sulphur removed from petroleum can be used for commercial purposes, this is not the primary reason for its removal. The main goal is to reduce harmful emissions, not to repurpose the sulphur.

• (d) The life span of engine silencers is not significantly affected by the presence of sulphur in petroleum products. The primary concern with sulphur is its contribution to air pollution and acid rain, not the wear and tear on engine components like silencers.

Thinking Process

Domestic sewage (household waste water) consists of everything which are transferred from residential blocks to sewer.

Answer

(d) Three type of impurities are found in waste water, suspended particles (solids). colloidal impurities and dissolved material (inorganic and organic) like calcium, ammonia, toxic material, phosphate, sodium, calcium and nitrate.

Out of them suspended solids like sand silt and clay impurities are easily removed, in sewage treatment plants.

• Bacteria: Bacteria are microorganisms that require specific biological or chemical treatments to be effectively removed from wastewater. This often involves processes like chlorination, UV treatment, or biological filtration, which are more complex and resource-intensive compared to the removal of suspended solids.

• Colloids: Colloidal impurities are particles that are small enough to remain suspended in water and do not settle out easily. They require coagulation and flocculation processes to aggregate the particles into larger clumps that can then be removed by sedimentation or filtration. These processes are more complex than simply removing suspended solids.

• Dissolved solids: Dissolved solids, such as salts, minerals, and organic compounds, are in solution and cannot be removed by simple filtration or sedimentation. They require advanced treatment methods like reverse osmosis, ion exchange, or chemical precipitation, which are more complicated and costly compared to the removal of suspended solids.

Answer

(a) Hepatitis-B is initially not caused by contamination of water, but by the exposure to infectious agents on the other hand, jaundice, cholera and typhoid are water and food borne diseases which are the caused the by contamination of food item.

• Jaundice: Jaundice can be caused by waterborne infections, particularly hepatitis A and E, which are transmitted through contaminated water.
• Cholera: Cholera is a waterborne disease caused by the bacterium Vibrio cholerae, which is typically spread through contaminated water.
• Typhoid: Typhoid fever is caused by the bacterium Salmonella typhi, which is often spread through contaminated water and food.

Answer

(d) Nuisance growth of aquatic plants and bloom the forming algae in natural water bodies is generally due to high concentration of dissolved organic and inorganic nutrients materials Phosphorus favours the growth of aquatic weed plants like Eichhornia (water hyacinth) and certain blue-green algae.

• Carbon: While carbon is essential for the growth of aquatic plants and algae, it is not typically the limiting factor in natural water bodies. High concentrations of carbon do not directly lead to nuisance growth; instead, it is the availability of nutrients like phosphorus that primarily drives such growth.

• Sulphur: Sulphur is a necessary nutrient for aquatic life, but it is not a primary driver of excessive plant and algae growth. High concentrations of sulphur compounds can lead to other environmental issues, such as the formation of hydrogen sulfide, but they do not directly cause nuisance growth of aquatic plants and algae.

• Calcium: Calcium is important for the structural integrity of aquatic organisms, particularly those with shells or exoskeletons, but it does not promote the excessive growth of aquatic plants and algae. High calcium concentrations are more likely to affect water hardness rather than contribute to nutrient-driven blooms.

Answer

(a) Algal bloom impart distinct colour to water due to their pigmens.

Pigment composition of several groups of algae.

• (b) Excretion of coloured substances: While some algae can excrete substances, the distinct colour of water during an algal bloom is primarily due to the pigments within the algae themselves, not substances they excrete.

• (c) Formation of coloured chemicals in water facilitated by physiological degradation of algae: The distinct colour is not due to the formation of new coloured chemicals in the water from the degradation of algae, but rather from the pigments that are naturally present in the algae.

• (d) Absorption of light by algal cell wall: The distinct colour is not due to the absorption of light by the algal cell wall, but rather due to the pigments within the algal cells that reflect specific wavelengths of light, giving the water its colour.

Answer

• Option (a) is incorrect because:

  • A. UV is incorrectly matched with Eutrophication. UV rays are related to snow blindness, not eutrophication.
  • B. Biodegradable organic matter is incorrectly matched with Biomagnification. It should be matched with BOD.
  • C. DDT is incorrectly matched with BOD. DDT is related to biomagnification.
  • D. Phosphates is incorrectly matched with Snow blindness. Phosphates are related to eutrophication.

• Option (b) is incorrect because:

  • A. UV is incorrectly matched with Snow blindness. This is correct.
  • B. Biodegradable organic matter is incorrectly matched with Eutrophication. It should be matched with BOD.
  • C. DDT is incorrectly matched with BOD. DDT is related to biomagnification.
  • D. Phosphates is incorrectly matched with Biomagnification. Phosphates are related to eutrophication.

• Option (d) is incorrect because:

  • A. UV is incorrectly matched with Snow blindness. This is correct.
  • B. Biodegradable organic matter is incorrectly matched with Biomagnification. It should be matched with BOD.
  • C. DDT is incorrectly matched with BOD. DDT is related to biomagnification.
  • D. Phosphates is incorrectly matched with Eutrophication. This is correct.

Answer

(b) MIC (Methyl Isocynate) was leaked from insecticide (SAVIN) unit of Union Carbide at Bhopal. Which lead to Bhopal Gas Tragedy. This chemical tragedy occured on December 2rd 1984 at Bhopal, the capital of Madhya Pradesh. In which around 2000-3000 people died on that some night.

• (a) $\mathrm{CO}_{2}$: Carbon dioxide (CO₂) is a common greenhouse gas and is not associated with the Bhopal gas tragedy. The disaster was specifically caused by the leakage of methyl isocyanate (MIC), not CO₂.

• (c) CFC’s: Chlorofluorocarbons (CFCs) are compounds used in refrigeration, air conditioning, and aerosol propellants. They are not related to the Bhopal gas tragedy, which was caused by the release of methyl isocyanate (MIC).

• (d) Methyl cyanate: Methyl cyanate is a different chemical compound from methyl isocyanate (MIC). The Bhopal gas tragedy was specifically due to the leakage of methyl isocyanate, not methyl cyanate.

Answer

Catalytic converters, having expensive metals namely platinum, palladium and rhodium as the catalysts are fitted into automobiles for reducing emission of poisonous gases and to convert unburnt hydrocarbons into $CO_{2}$ and $H_{2} O$.

Motor vehicles equipped with catalytic to converter need to use unleaded petrol because lead in the petrol, inactivates the catalyst and increases the hydrocarbon emission, there by harming the environment.

Answer

In 1987, the Air (Prevention and Control of Pollution) Act was amended to include noise as a source of air pollution.

Answer

In Delhi, the entire public surface transport especially road transport runs on compressed Natural Gas (CNG)

Answer

The source of silt that get deposited in overhead water tank are soil particles, which are carried out with water from the source of supply like deep borewell, rivers, etc.

Answer

The phenomenon wherein effluents from the industries and homes accelerate the natural and cultural ageing process of lakes and other water bodies that normally may take thousands of years is called accelerated eutrophication

Answer

The fine particulate (PM of size $2.5 \mu \mathrm{m}$ or less) can problems cause

(i) Breathing and respiratory

(ii) Irritation

(iii) Inflammations

(iv) Damage to the lungs and premature death

Answer

Polyblends are natural man made fibres, made by the mixture of two or more polymers especially plastic waste products

Answer

Polyblend is a fine powder of recycled modified plastic. The binding property of plastic makes the road last longer besides giving added strength to withstand more loads. This is because

(i) Plastic increases the melting point of the bitumen which would prevent it from melting in India’s hot and extremely humid climate, where temperature frequently cross $50^{\circ} \mathrm{C}$.

(ii) Rainwater will not seep through because of the plastic in the tar.

Answer

Wind breakers or shelter belts provide shelter from wind and protect soil from erosion. Jamun and imli and some other trees like babul, Lawsonia, Thevetia and Calotropis acts as wind breakers in the agricultural field.

Answer

Chemical fertiliser unit, thermal power plant, refineries, smelting and metallurgical processing units steel mills, and the industries using steam or water as coolant causes both air and thermal pollution. The chemical release form these Industries (if rich in nitrogen and phosphorus) may result in eutrophication.

Answer

The extensive growth of planktonic (free-floating) algae in water bodies due to the presence of organic matter in water (cnitrogen and phosphores) that acts as a food source is called an algal bloom. This imparts a distinct colour to the water bodies.

Answer

Biomagnification refers to the increase in the concentration of the toxic substances at successive trophic level Is in the food chain.

This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted and when this organism is eaten up by another animal of higher trophic level, it is passed on to this and then to the next higher trophic level and so on.

Answer

The three major kinds of impurities in domestic waste water are

(i) Dissolved salts such as nitrates, phosphates, other nutrients, toxic, metal ions and organic compounds.

(ii) Biodegradable organic matter.

(iii) Pathogenic microorganisms.

Answer

Reforestation is the process of restoring a forest that had once existed but was removed at some point of time in the past. Though, it can occur naturally in a deforested area but we can expedite it by planting trees with due consideration to biodiversity that earlier existed in that area.

Answer

The best solution for the treatment of electronic wastes is to recycle it. Electronic waste recycling facilities have advanced considerably and now they can be recycled $95-98 \%$ by weight.

Recycling has two fold benefits

(i) It prevents the toxic components of computers from entering the delicate environment and ground water via landfill.

(ii) It also slows the use and mining of primary raw materials.

Answer

Yes, it is true, that the placing/using carpets on floor and curtains on wall surface, windows, reduces noise level. This is because the curtains and carpets on wall surface and carpet acts as muffling device and absorb sounds of moderate level.

Answer

The technology used to run vehicles on dual mode like petrol or compressed natural gas is said to be hybrid vehicle technology. These vehicles runs on either petrol or CNG. As CNG is a clean and green fuel so it is helpful to reduce environmental pollution and also to conserve petrol, fossil fuel.

Answer

Yes, it is true, in case of zero level of dissolved oxygen (DO), the water becomes septic. Organic pollution like fertiliser in aquatic bodies is responsible for lowering (upto zero) the level of dissolved oxygen.

Answer

The common green house gases are $CO_{2}, CH_{4}, CFC$, oxide of nitrogen $\left(N_{2} O\right)$, water vapour and $O_{3}$. The level of $CO_{2}$ (green house gas) is increasing due to large scale deforestation, change in land use and unlimited buring of fossils fuel and is leading to global warming.

The source of methane and other main green house gases are garbage dump, incomplete decomposition by anaerobic methanogens, flooded paddy field and marshy land. About 90-95 % of $\mathrm{CH}_{4}$ is produced/generated by rice fields of Asia.

Answer

A common practice to grow and maintain trees and shrub near the boundary wall of residential, official building acts as a barrier for sound and check noise pollution. This green belt of tree and shrub also acts as an effective measure to check primary air pollutants like dust, flyash, etc.

Answer

It is our moral duty to protect, restore and conserve/preserve forest as they are highly beneficial for mankind In India, around 30 % of land was covered by forest in early 20th century, which has been reduced to $18-19 \%$ by the year 2000 . National Forest Commission of India (1988) recommended a relatively large forest cover (67 %) for the hills and $33 \%$ for the plains.

Recommendation a large forest area for hills is due to its properties like checking soil erosion, percolation and recharging ground water, checking landslide and other natural calamities and to maintain the original flora and fauna of hills.

Answer

Slash and burn agriculture can be environment friendly if

(i) small widely scattered plots are used for cultivation as the forest ecosystem will not suffer damage.

(ii) crop rotation is used so that soil does not loose fertility entirely.

(iii) keeping cropping period small and fallow (unplanted) period longer.

Answer

The main idea behind joint forest management concept introduced by the Government of India was involving the local communities in the forest conservation.

This concept was adopted considering the extraordinary courage and dedication the local people showed in protecting the wildlife through the movements like Bishnoi’s is movement in Jodhpur and Chipko Movement in Garhwal Himalayas.

Answer

The inflammation of cornea caused due to the excessive absorption of ultravioet-B radiations is called snow-blindness cataract.

Answer

High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of egg shell and their premature breaking, eventually causing decline in bird populations.

Answer

(i) Figure A is solar energy panel and figure B is wind mill device. Both devices produce power without polluting the environment.

(ii) Solar lamp (lantern) (made up of a LED lamp, a photo-voltaic solar panel and rechargeable battery) and solar hot water system (geyser) are the two application of solar energy.

(iii) A solar cell is also called as photovoltaic cell. It is a form of photoelectric cell which converts the light energy into electrical energy by photovoltaic cell.

Answer

Solid waste can be biodegradable recyclable non-biodegradable, and can be categoriesed as municipal wastes (se-wage), industrial waste, hospitals and nursing wastes and electronic waste. Irrepairable computers, mobiles and other electronic goods are often known as ’ $e$ ’ waste or electronic waste.

Source of e-waste Majority of the developing countries like China, Pakistan and India import irrepairable electronic goods for their valuable metals like copper, nickel and gold.

Disposal of e-waste Such waste should be burried in landfills or incinerated. In developing countries, metal from e-waste is extracted manually. So, during working with e-waste, one can expose with toxic substances present in it, and may get affected by skin diseases in future. However, recycling is the only solution for the treatment of electronic waste.

Answer

Organic farming system primarily aims at sustainable production in an eco-friendly and pollution free environment. The land is cultivated by using techniques such as crop rotation, green manure, composting and biological pesticides alongwith beneficial microbes (biofertilisers) instead of chemical fertilisers and pesticides, etc.

Benefits of organic farming are

(i) Maintains long-term soil fertility

(ii) Controls pests and diseases without harming the environment.

(iii) Ensures that water stays clean and safe.

(iv) Makes use of resources which the farmer already has, to make it economic.

(v) Helps produce nutritious food and high quality crops.

Organic farming in India

Using organic farming techniques makes much more sense for developing nations like India. As we know that modern, intensive agriculture makes the use of expensive chemical fertilisers and herbicides, which leach out from the soil and pollute rivers, lakes and water bodies and also damage the soil fertility in the long run.

Answer

Water logging and soil salinity is caused by extensive irrigation without proper drainage of water.

Continuous presence of water draws salt to the surface of the soil, which gets deposited as a thin crust on the land surface or start collecting at the roots of the plants.

Adverse effects

(i) Increased salt content stunts the growth of crop plants.

(ii) Root cells saturated with saline water gets damaged.

(iii) Plants die.

(iv) Crop yield gets affected.

(v) Financial loss to the farmers.

Although properly managing the soil-water system can correct the salination and water logging, but the economic costs of this are very high

Answer

Multipurpose trees are those tree which on plantation fulfills a number of purpose, like shade, providing, soil improvement, provide wood, fruit and food etc. In other words, multipurpose trees serve a wide variety of function and services for human needs.

Neem (Azardicta, indica) is known for its medicinal properties. Its fruit, leaves, wood and oil extracted from wood is used in most of the ayurvedic medicines. Its wood is pest resistant due to chemical azardiction. Another most important tree is coconut palm.

Its botanical name is Coccos nucifera and belongs to the family-Palmae, it serves a variety of function. As we get oil, wood and food fibre, from this plant. This plant has fibre, medicinal and commercial importance.

Some other multipurpose trees are Moringa oleifera and Gliricidia sepium, which is widely used for fences in central America and provide fire wood fooder and fix atmospheric $\mathrm{N}_{2}$ While M.oleifera is commonly used for animal forage and shade, its leaves are edible.

Answer

Characteristics of a modern landfill includes

(i) Methods to contain leachate such as lining clay or plastic liners.

(ii) Compaction and covering of the waste to prevent it from being blown by wind

(iii) Installation of a landfill gas extraction system to extract the gas for use in generation of power.

The use of modern landfill sites must be promoted due to the following reasons

(i) They stimulate the waste prevention via recycling and recovery of waste.

(ii) They create a uniform cost for the disposal of waste which consequntly will prevent the unecessary transport of waste.

(iii) They prevent or reduce the negative eftects on the envirionment, as well as the risks to human health arising from the landfilling of the waste.

Answer

Electrostatic precipitator can remove over $99 \%$ particulate matter present in the exhaust from a thermal power plant by the following mechanism

(i) It has electrode wires that are maintained at several thousand volts, which produce a corona that releases electrons.

(ii) These electrons attach to dust particles giving them a net negative charge.

(iii) The collecting plates are grounded and attract the charged dust particles.

(iv) The velocity of air between the plates is kept low enough to allow the dust to fall.

Answer

(i) The ecological term used to describe the DDT accumulation at different trophic levels is called biomagnification.

(ii) High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of egg shell and their premature breaking, eventually causing decline in bird populations.

(iii) Yes, DDT accumulation can lead to eutrophication.

(iv) It increases the BOD, resulting in a decrease in dissolved oxygen in the water body.

(v) Eating fish that has accumulated mercury, a heavy metal, causes a disease called Minamata. It is characterised by diarrhoea, haemolysis, numbness, deafness, mental derangement, meningitis and death.