Environmental Issues

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).

The Montreal Protocol was signed at Montreal (Canada) in 1987 (effective from 1989) to control the emission of ozone depleting substances.

Presence of large amounts of nutrients in waters causes excessive growth of planktonic 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.

Algal blooms cause deterioration of the water quality and fish mortality. Eutrophication is the natural aging of a lake by nutrient enrichment of its water. Presence of large amounts of nutrients in waters also causes excessive growth of planktonic (free-floating) algae, called an algal bloom.

There are several ways of removing particulate matter; the most widely used of which is the electrostatic precipitator, which can remove over 99 per cent particulate matter present in the exhaust from a thermal power plant.

Every petrol-driven vehicle must have a valid PUC (Pollution Under Control) certificate; the test measures the carbon monoxide and hydrocarbons in the exhaust. This is a compulsory step taken by the government.
CNG was made compulsory only for public transport buses in Delhi (by the end of 2002), not for all buses and trucks in the country.
There is no compulsory mixing of 20% alcohol with petrol or 20% biodiesel with diesel.
The norms prescribe much lower sulphur levels (350 ppm and then 50 ppm in diesel under the Euro norms), not simply a 500 ppm limit.
Hence the correct step is compulsory PUC certification of petrol-driven vehicles.

Thermal power plants that burn coal release particulate and gaseous air pollutants.
The electrostatic precipitator is the most widely used device for removing particulate matter; it can remove over 99 percent of the particulate matter present in the exhaust of a thermal power plant.
It has electrode wires maintained at several thousand volts, which produce a corona that releases electrons.
These electrons attach to the dust particles and give them a net negative charge; the charged particles are then attracted to and collected on earthed plates.
So electrostatic precipitators control the emission of SPM (suspended particulate matter).
Gases such as $SO_2$ are removed by a scrubber, and CO and $NO_x$ from vehicles are controlled by catalytic converters.

In the human eye, the cornea absorbs UV-B radiation. A high dose of UV-B causes inflammation of the cornea, called snow-blindness.

Greenhouse gases absorb the long-wave (infra-red) radiation emitted by the earth and so warm the atmosphere.
The relative contributions of the greenhouse gases to total global warming are: $CO_2$ 60%, $CH_4$ 20%, CFCs 14% and $N_2O$ 6%.
So $CO_2$ and $N_2O$ are both recognised greenhouse gases.
CO and $SO_2$ are air pollutants but are not listed among the greenhouse gases, and ozone is not one of the four major contributors.
Among the given pairs, the one in which both gases are major greenhouse gases is $CO_2$ and $N_2O$.

Relative contribution of the greenhouse gases to total global warming: $CO_2$ 60%, $CH_4$ 20%, CFCs 14% and $N_2O$ 6%.
The two largest contributors are carbon dioxide (60%) and methane (20%).
Hence the two gases are $CO_2$ and $CH_4$.

The four main greenhouse gases and their relative contributions to total global warming (as given in NCERT) are:
Carbon dioxide ($CO_2$) - 60 percent
Methane ($CH_4$) - 20 percent
Chlorofluorocarbons (CFCs) - 14 percent
Nitrous oxide ($N_2O$) - 6 percent
Checking the pairs: $CO_2$ is 60 percent (not 86 or 40), $N_2O$ is 6 percent (not 18) and CFCs are 14 percent (not 30).
The only pair in which both values are correct is CFCs 14% and Methane 20%.

Greenhouse gases such as $CO_2$, methane and nitrous oxide are released mainly by burning fossil fuels in industry, power plants and transport.
At the time of this paper, the U.S.A., being the most industrialised country with very high per capita energy use, released the largest amount of greenhouse gases in the world.
(In later years China's total emissions became the largest, though the U.S.A. still has much higher emissions per person.)
So, at the time of this question, the maximum greenhouse gas was released by the U.S.A.

The Air (Prevention and Control of Pollution) Act was amended in 1987 to include noise as an air pollutant.

According to the CPCB, particulate matter of size 2.5 micrometers or below (PM2.5) is considered responsible for causing greater harm to human health, as it can penetrate deep into the respiratory system.

Water with high BOD contains large amounts of organic matter that consume dissolved oxygen during microbial decomposition, so contamination of a lake with such water decreases the amount of dissolved oxygen in the lake, harming aquatic life.

Deforestation is the conversion of forested areas to non-forested areas (A-II); Reforestation is the process of restoring a forest that once existed but was removed (B-IV); the Green-house effect is responsible for heating of Earth's surface and atmosphere (C-I); Eutrophication is the natural ageing of a lake by nutrient enrichment of its water (D-III).

BOD is inversely related to dissolved oxygen (A is correct); low dissolved oxygen combined with high BOD leads to loss of aquatic life (B is correct); both BOD and dissolved oxygen are indicators of water body health (D is correct) and are both affected by the amount of organic matter present (E is correct). High BOD actually leads to LOW dissolved oxygen, not high (C is incorrect). So A, B, D, E only.

CNG burns most efficiently, is cheaper than petrol or diesel, and cannot be siphoned off by thieves or adulterated. So (a), (c) and (d) are correct.

Greater UV radiation from ozone depletion causes mutations, skin cancer, eye damage and reduced immunity.
Liver cancer is not one of its health risks.

Ozone is called 'good' or 'bad' depending on where it is found.
Good ozone is found in the upper part of the atmosphere called the stratosphere, where it acts as a shield absorbing the harmful ultraviolet radiation from the sun.
Bad ozone is formed in the lower atmosphere (troposphere), where it is a pollutant that harms plants and animals.
The thickness of the ozone layer is measured in Dobson units.
Hence good ozone is found in the stratosphere.

The Montreal Protocol is an international treaty signed at Montreal, Canada, in 1987 (effective from 1989).
Its aim is to control the emission of ozone-depleting substances such as CFCs, in order to protect the ozone layer of the stratosphere.
Control of $CO_2$ and other greenhouse gases is the aim of the Kyoto Protocol.
Biodiversity conservation was the subject of the Earth Summit at Rio de Janeiro (1992).
Hence the Montreal Protocol aims at the reduction of ozone depleting substances.

The Montreal Protocol was signed at Montreal (Canada) in 1987 and became effective in 1989.
It laid down definite control strategies and time-bound road maps, separately for developed and developing countries, for reducing the emission of CFCs and other ozone-depleting chemicals.
The Vienna Convention (1985) only provided a general framework for protecting the ozone layer, without specific control measures.
The Rio de Janeiro conference (1992) dealt with biodiversity and sustainable development, and the Kyoto Protocol (1997) with greenhouse gases.
Hence the specific control strategies were adopted by the Montreal Protocol.

Ozone in the stratosphere absorbs the harmful ultraviolet radiation of the sun.
Chlorofluorocarbons (CFCs) and other ozone depleting substances release chlorine atoms in the stratosphere, which break down ozone and have caused the ozone hole over Antarctica.
Recognising this, an international treaty known as the Montreal Protocol was signed at Montreal (Canada) in 1987 to control the emission of ozone depleting substances.
It became effective in 1989.
Subsequently many more efforts were made, and protocols have laid down definite roadmaps, separately for developed and developing countries, for reducing the emission of CFCs and other ozone depleting chemicals.
So the Montreal Protocol was passed in the year 1987.

World Ozone Day is celebrated on 16th September. 5th June – World Environment Day; 22nd April – Earth Day; 21st April – National Yellow Bat Day.

$O_3$ (ozone) is a secondary pollutant. Secondary pollutants are formed by the reaction of primary pollutants. CO – quantitative pollutant; $CO_2$ – primary pollutant; $SO_2$ – primary pollutant.

UV rays act on CFCs, releasing Cl atoms; chlorine reacts with ozone in a sequential (catalytic) manner, converting it into oxygen. Carbon, oxygen and Fe are not related to ozone layer depletion.

Eutrophication – nutrient enrichment Sanitary landfill – waste disposal Snow blindness – UV-B radiation Jhum cultivation – deforestation Correct match: a-iii, b-iv, c-i, d-ii.

Aerosols cause various problems to agriculture through their direct or indirect effects on plants; they do not increase agricultural productivity. Continually increasing air pollution may represent a persistent and largely irreversible threat to agriculture in the future.

The ozone layer in the stratosphere prevents UV radiation from reaching the earth. Release of CFCs depletes ozone, forming holes that allow UV radiation to reach the earth and cause skin cancer.

Organic waste in sewage is decomposed by microbes that use up dissolved oxygen, increasing the biological oxygen demand (BOD). This causes death of fish due to lack of oxygen.

Ley farming involves rotation of crops with legume plants and grass pasture to improve the fertility and health of the soil; it also helps prevent pests by disrupting their life cycles.

DDT accumulates along the food chain (biomagnification) and reaches high concentrations in fish-eating birds.
It disturbs calcium metabolism in birds, which causes thinning of the egg shell and premature breaking of eggs.
So many of the eggs laid did not hatch and the bird population declined.

Biomagnification is the increase in concentration of a toxicant at successive trophic levels.
It happens because the toxic substance accumulated by an organism cannot be metabolised or excreted, and is passed on to the next higher trophic level.
DDT is insoluble in water but soluble in fats (lipo-soluble); it is stored in the body fat of organisms and is not broken down.
So its concentration rises at each step: for example, from 0.003 ppb in water to 25 ppm in fish-eating birds.
Hence DDT is biomagnified because it is lipo soluble.

The 2011 UN Conference of Parties on Climate Change was held in Durban, South Africa, where it was agreed to work towards a new treaty to limit carbon emissions.

The Kyoto Protocol was adopted at the third Conference of Parties (CoP-3) of the UNFCCC, held in Kyoto, Japan in 1997.

Silent Spring describes the entry of DDT into food chains and its effects on animals at different trophic levels, i.e. pesticide pollution.

Eutrophication is the natural ageing of a lake by nutrient enrichment of its water.
Streams draining into a lake bring nutrients such as nitrates and phosphates, which encourage the growth of aquatic organisms and algal blooms.
Organic remains accumulate at the bottom, the lake becomes shallower and warmer, and it is gradually converted into land.
Pollutants from sewage and agricultural and industrial wastes greatly speed up this process (cultural or accelerated eutrophication).
It is a phenomenon of standing fresh water bodies and is not seen on mountains or deserts; the open ocean is too large and well mixed.
Hence eutrophication is often seen in fresh water lakes.

Domestic sewage contains a large amount of biodegradable organic matter.
Micro-organisms in the receiving water body decompose this organic matter, and in doing so they consume a lot of oxygen.
As a result there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge (high BOD), which causes mortality of fish and other aquatic creatures.
Although the impurities are only about 0.1%, they include pathogens and make the water unfit for drinking.
Hence the increased microbial activity uses up dissolved oxygen.

BOD is the amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria.
It is therefore an indirect measure of the organic matter present in the water: the greater the BOD, the greater the polluting potential.
Sewage contains a large amount of biodegradable organic matter, so when it mixes with river water the BOD increases, and the dissolved oxygen falls sharply.
An algal bloom also adds organic matter when the algae die, so BOD does not remain unchanged.
BOD is not a count of any particular bacterium such as $Salmonella$.
Hence BOD increases when sewage gets mixed with river water.

Excessive use of nitrogenous fertilisers leads to a high concentration of nitrates in ground water and drinking water.
In the intestine of infants, nitrates are reduced to nitrites by bacteria.
Nitrites enter the blood and oxidise the iron of haemoglobin from the ferrous ($Fe^{2+}$) to the ferric ($Fe^{3+}$) state, forming methaemoglobin.
Methaemoglobin cannot carry oxygen, so the oxygen supply to the tissues falls.
The skin of the baby turns bluish (cyanosis); the condition is called methaemoglobinaemia or 'blue baby' syndrome.
It is not caused by chlorides, dissolved oxygen or total dissolved solids.
So the 'blue baby' syndrome results from methemoglobin.

Lichens are very sensitive to air pollution, especially $SO_2$, and do not grow in polluted areas. Their luxuriant growth shows the location is not polluted.

The Air (Prevention and Control of Pollution) Act came into force in 1981 and was amended in 1987 to include noise.

The Bhopal gas tragedy took place on the night of 2–3 December 1984 at the Union Carbide pesticide plant in Bhopal.
About 40 tonnes of the highly toxic gas methyl isocyanate (MIC) leaked from a storage tank.
Thousands of people died and many more suffered lasting damage to their lungs and eyes.
It was a chemical (industrial gas leak) disaster; no radioactive material was involved, so there was no radioactive fall out.
Hence the wrong statement is that radioactive fall out engulfed Bhopal.

Particulate matter is one of the major air pollutants released from thermal power plants, smelters, industries and vehicles.
According to the Central Pollution Control Board (CPCB), particulate size 2.5 micrometers or less in diameter (PM 2.5) is responsible for causing the greatest harm to human health.
These fine particulates can be inhaled deep into the lungs, as they are not filtered out by the nose and upper respiratory tract.
They can cause breathing and respiratory symptoms, irritation, inflammation and damage to the lungs, and premature deaths.
Larger particles are trapped in the upper respiratory passages and are removed more easily.
So the particulate size responsible for the greatest harm is 2.5 micrometers or less.

Good ozone forms a layer in the stratosphere, where it absorbs harmful ultraviolet radiation.

Ozone in the upper atmosphere (stratosphere) is good ozone: it absorbs ultraviolet radiation from the sun and protects living organisms.
It is ozone in the lower atmosphere (troposphere) that is harmful.
So the statement that ozone in the upper part of the atmosphere is harmful to animals is wrong.

A scrubber removes gases like sulphur dioxide: the exhaust is passed through a spray of water or lime.
Particulate matter is removed by electrostatic precipitators.

Global warming can be controlled by cutting down the use of fossil fuel, improving the efficiency of energy usage, reducing deforestation and planting trees.

A renewable resource is one that can be replenished by natural processes or regeneration within a reasonable time.
A forest can regenerate, so it is renewable; but if it is exploited faster than it regrows, it can be used up, so it is also exhaustible.
Coal, petroleum and minerals take millions of years to form; they are non-renewable exhaustible resources.
Hence a renewable exhaustible natural resource is the forest.

dB stands for decibel, the unit in which the intensity (loudness) of sound is expressed.
Noise is undesired high level of sound and is recognised as an air pollutant; noise pollution is therefore measured in decibels.
A sound level of 150 dB or more, such as that of a jet plane or rocket taking off, may damage the ear drums and permanently impair hearing.
Hence dB is used for the quantitative expression of a particular pollutant (noise).

Sound intensity is measured in decibels (dB).
Normal conversation is about 30–60 dB (often quoted as about 60 dB).
A whisper is about 20 dB, heavy traffic about 80–90 dB, and a jet plane at take-off about 150 dB. Sound above 80 dB is harmful, and above 120 dB causes pain and can damage hearing.
So the intensity of sound in normal conversation is 30–60 decibel.

The Chipko movement started in 1974 in the Garhwal Himalayas.
Local women showed enormous bravery in protecting trees from the axes of contractors by hugging them ('chipko' means to hug or cling).
It is a well-known example of people's participation in the conservation of forests.
Hence the Chipko movement was launched for the protection of forests.

Biofuels are fuels obtained from biological sources and are renewable substitutes for fossil fuels.
Jatropha curcas (family Euphorbiaceae) is a hardy shrub that grows on wastelands and in dry areas.
Its seeds contain about 30 to 40 percent of non-edible oil, which is converted into biodiesel by transesterification.
For this reason Jatropha is being cultivated and tried in India as a biofuel (biodiesel) substitute for fossil fuels.
Musa is banana, Aegilops is a wild grass related to wheat, and Azadirachta is neem, known for the biopesticide azadirachtin; none of these is the biodiesel crop.
So the answer is Jatropha.

Biodiesel is a renewable fuel obtained from vegetable oils by transesterification.
Pongamia pinnata (pongam or karanja) is a leguminous, nitrogen-fixing tree whose seeds contain 30-40 percent oil.
It is commonly planted as an ornamental and shade tree, and in the Indian countryside its seed oil is being used as a source of biodiesel.
Jatropha is another important biodiesel plant.
Sugarcane and beetroot are sources of sugar, which is fermented to give ethanol (bioethanol), not biodiesel.
Euphorbia species are petrocrops that yield latex rich in hydrocarbons, but they are not the source being utilised for biodiesel in the countryside.
So the answer is Pongamia.

(i) Urea and phosphate fertilisers used in the nearby crop fields are washed into the lake with run-off water. They enrich the water with nitrates and phosphates.
This nutrient enrichment causes an excessive growth of planktonic algae, called an algal bloom, which is the process of accelerated (cultural) eutrophication.
(iii) The algal bloom turns the water green and gives it a foul smell. When the algae die, decomposer microbes break them down and consume the dissolved oxygen of the water; the biochemical oxygen demand rises sharply.
The fall in dissolved oxygen, together with toxins released by some bloom-forming algae, causes heavy mortality of fishes within a few days.
(ii) DDT undergoes biomagnification over a long period and mainly harms the top consumers such as fish-eating birds; it does not cause such sudden mass death of fishes.
(iv) is opposite to what happens: the phytoplankton population increases greatly instead of declining.
So the two main causes are (i) and (iii).

Chemical fertilisers, mainly nitrates and phosphates, that are used in excess are washed from the fields into nearby ponds, lakes and rivers.
This nutrient enrichment causes heavy growth of algae (algal bloom) and, later, depletion of oxygen in the water. The process is called eutrophication. So this statement is correct.
Rhizobium fixes nitrogen in the root nodules of legumes, but Azotobacter is a free-living nitrogen-fixing bacterium of the soil; it does not live in root nodules.
Anabaena and Nostoc are nitrogen-fixing cyanobacteria. Phosphates are mobilised mainly by mycorrhizal fungi.
Maize, like other crops, can be grown without chemical fertilisers, using organic manures and biofertilisers (organic farming).
So the correct statement is that extensive use of chemical fertilizers may lead to eutrophication of nearby water bodies.

Biochemical oxygen demand (BOD) is the amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidised by micro-organisms.
A higher BOD value means that the water sample is more polluted by biodegradable organic matter.
Distillery effluent (spent wash) is extremely rich in organic matter and has the highest BOD of the four, of the order of 40,000 mg/L.
Sugar mill effluent also carries a heavy load of sugars and other organic matter, so its BOD is high, though far below that of distillery effluent.
Domestic sewage and paper mill effluent have much lower values; taking the figures used in the source, paper mill effluent is the lowest and sewage comes next.
So the ascending order of BOD is PE < S < SE < DE.

BOD (biochemical oxygen demand) is the amount of oxygen required by micro-organisms to oxidise the organic matter present in one litre of water; it is a measure of organic pollution.
Effluents with a high BOD use up the dissolved oxygen of the receiving water and kill the aquatic life.
So waste water must be treated to bring down its BOD before it is released into rivers and lakes.
The Central Pollution Control Board (CPCB) has prescribed that the BOD of industrial and municipal waste water discharged into natural surface waters should be less than 30 ppm (30 mg/L).
Clean water has a BOD of less than about 5 ppm, while untreated sewage has a BOD of a few hundred ppm.
So the prescribed limit is less than 30 ppm.

Bioindicators of water pollution are organisms whose presence shows that the water is polluted with organic matter and is poor in dissolved oxygen.
Blood-worms (larvae of Chironomus) contain haemoglobin and can live in water with very little oxygen, so they indicate pollution.
Sludge-worms (Tubifex) live in the organic sludge at the bottom of heavily polluted water.
Sewage fungus (a slimy growth of bacteria such as Sphaerotilus and associated organisms) grows in water receiving sewage.
Stone flies (Plecoptera), on the other hand, have nymphs that need clean water rich in dissolved oxygen; they disappear when the water becomes polluted.
Their presence therefore indicates clean, unpolluted water, so they are not indicators of water pollution.
So the answer is stone flies.

Photochemical smog is formed in warm, dry and sunny conditions in cities with heavy traffic.
The primary pollutants, oxides of nitrogen ($NO$, $NO_2$) and unburnt hydrocarbons from vehicle exhausts, react in the presence of sunlight.
$NO_2$ is split by sunlight to give nascent oxygen, which combines with $O_2$ to form ozone ($O_3$).
Ozone and the oxides of nitrogen react with the hydrocarbons to form secondary pollutants such as peroxyacyl nitrate (PAN), formaldehyde and acrolein.
So the main components of photochemical smog are ozone, nitrogen dioxide (and other nitrogen oxides) and PAN, which make it oxidising and irritating to the eyes and lungs.
Carbon dioxide is not a component of photochemical smog.
So photochemical smog pollution does not contain carbon dioxide.

Nuclear power plants produce radioactive wastes, which are very harmful and must be stored safely; correctly matched.
Burning of fossil fuels (coal, petroleum) releases large amounts of $CO_2$; correctly matched.
Burning of biomass (wood, crop residues, dung) also releases $CO_2$; correctly matched.
Solar energy is a clean, non-polluting, renewable source of energy. Using it does not release greenhouse gases, so it does not cause the greenhouse effect.
(The greenhouse effect is caused by gases such as $CO_2$, $CH_4$, CFCs and $N_2O$ trapping the heat radiated by the earth.)
So the mismatched pair is solar energy - greenhouse effect.

Disinfection is the destruction of disease-causing micro-organisms in water.
Chlorine is the most commonly used disinfectant for drinking water; it kills bacteria and other pathogens.
Chloramines (formed from chlorine and ammonia) are used because they give a longer lasting disinfection.
Ozone is a powerful oxidising agent and is also used to disinfect drinking water.
Phenyl (phenol-based disinfectant) is used for cleaning floors and toilets. It is toxic and gives an unpleasant taste and smell, so it is never used for disinfecting drinking water.
So the one not used is phenyl.

The Kyoto Protocol (1997) is an international agreement under the UN Framework Convention on Climate Change; it commits industrialised countries to reduce their emissions of greenhouse gases. So Kyoto Protocol - climatic change is correct.
The Montreal Protocol (1987) deals with the protection of the ozone layer by controlling ozone depleting substances, not with global warming.
The Basel Convention (1989) deals with the control of the movement and disposal of hazardous wastes across borders, not with biodiversity conservation.
The Ramsar Convention (1971) deals with the conservation of wetlands, not with ground water pollution.
So the correctly matched pair is Kyoto protocol - climatic change.

Irrigation water always contains dissolved salts.
When fields are irrigated heavily for a long time without proper drainage, the water table rises (waterlogging), and the water evaporates from the soil surface, leaving the salts behind.
The salts are also drawn up to the surface by capillary action.
Over the years the salts accumulate in the upper layers of the soil, forming a white crust; the soil becomes saline and its fertility falls, and crop growth is badly affected.
This problem of salinity is seen in many irrigated areas, for example parts of Punjab and Haryana.
So prolonged liberal irrigation is likely to create the problem of salinity.

Lead is a toxic heavy metal that enters the body from leaded petrol exhaust, lead paints, batteries and contaminated water.
It damages the nervous system (especially in children), kidneys and blood formation, since it inhibits enzymes of haem synthesis.
Normal blood lead levels are only a few micrograms per 100 ml.
A blood lead level of 10 $\mu g$/100 ml (10 $\mu g$/dL) has been taken as the level of concern; at or above this value harmful effects, especially on the mental development of children, begin, so it is considered alarming.
So lead concentration in blood is considered alarming if it is 10 $\mu g$/100 ml.

In December 1984, a large amount of methyl isocyanate (MIC, $CH_3NCO$) gas leaked from the Union Carbide pesticide factory in Bhopal.
Water entered a storage tank of MIC. MIC reacts with water in a strongly exothermic reaction:
$CH_3NCO + H_2O \rightarrow CH_3NH_2 + CO_2$ (with release of a large amount of heat)
The heat raised the temperature and pressure in the tank, and the safety systems failed, so a cloud of toxic MIC gas escaped into the city. Thousands of people died and many more suffered lung and eye damage.
So the tragedy took place because methyl isocyanate reacted with water.

Terra rossa (Italian for 'red earth') is a red clayey soil formed on limestone in Mediterranean regions. Its name refers to its red colour (due to iron oxides), not to roses, and it has no special suitability for growing roses. So this pair is not correctly matched.
Chernozems (black earth) of the grasslands of Russia and Ukraine are very rich in humus and are considered among the most fertile soils in the world; correctly matched.
Black soil (regur) of the Deccan is clayey and rich in calcium carbonate, magnesium and iron; correctly matched.
Laterite soil, formed by intense leaching in hot, wet regions, is rich in hydrated oxides of aluminium and iron; correctly matched.
So the pair not correctly matched is Terra rossa – most suitable for roses.

To reduce dependence on imported petrol and to reduce pollution, the Government of India started the ethanol blended petrol programme in 2003.
Under this programme, petrol was allowed to be blended with up to 5 percent ethanol (alcohol made from sugarcane molasses), initially in nine states.
(The blending target was raised in later years, but at the time of this paper it was 5 percent.)
So the amount of alcohol permitted for mixing in petrol was 5%.

Escherichia coli (a coliform bacterium) lives normally in the intestine of humans and other warm-blooded animals and is passed out in faeces in huge numbers.
Its presence in water shows that the water is contaminated with sewage (faecal matter) and may contain disease-causing organisms. So the coliform count (E. coli count) is the standard test of the quality of drinking water.
Eichhornia (water hyacinth) and Lemna grow abundantly in nutrient-rich (eutrophic) water but are not the standard indicator. Entamoeba is a pathogen, not a routine indicator.
So the common indicator organism of water pollution is Escherichia coli.

Escherichia coli is a normal inhabitant of the human (and animal) large intestine and is passed out in faeces in very large numbers.
So its presence in a water sample shows contamination with sewage (faecal matter), and therefore the possible presence of intestinal pathogens (e.g. those causing cholera, typhoid and dysentery).
The coliform (E. coli) count is the standard test of drinking water quality. It does not indicate heavy metals, industrial effluents or pollen.
So E. coli is used as an indicator of pollution of water with faecal matter.

Fluoride is present naturally in the groundwater of some regions (in India, parts of Rajasthan, Andhra Pradesh, Gujarat and others).
In small amounts (about 1 ppm) it protects teeth from decay, but excess fluoride (above about 1.5 ppm) causes fluorosis.
The first and most common effect is dental fluorosis: mottling, brown staining and pitting of the tooth enamel. Higher levels also cause skeletal fluorosis (stiff joints, bone deformities).
So fluoride pollution mainly affects the teeth (and bones).

Some organisms can live only in clean, well oxygenated water, so their presence or absence indicates the quality of water.
Stonefly larvae (and mayfly nymphs) need high dissolved oxygen and are very sensitive to pollution. They disappear from polluted water, so they are indicators of clean water.
Water hyacinth (Eichhornia) and blue green algae grow abundantly in polluted, nutrient-rich (eutrophic) water, and Hydrilla also tolerates such water.
So the larva of the stone fly is absent in polluted water.

BOD (biochemical oxygen demand) is the amount of oxygen consumed by microorganisms (bacteria) in decomposing (oxidising) the organic matter present in a litre of water, usually measured over 5 days at 20 °C.
It is a measure of the amount of biodegradable organic pollution: the more organic waste (e.g. sewage), the higher the BOD.
So BOD is the amount of $O_2$ utilised by micro-organisms for decomposition.

Long exposure to fine dust in workplaces can damage the lungs. Fine particles (smaller than 2.5 $\mu m$) reach deep into the alveoli, causing inflammation and fibrosis.
Cement dust contains silica, chromium compounds and other irritants. Workers in cement factories are exposed to heavy dust and have an increased risk of chronic lung diseases and lung cancer.
(Coal mining mainly causes coal workers' pneumoconiosis or black lung, and the link to cancer is weaker.)
So, as per the answer key, the reason of lung cancer among these is the cement factory.

Relative biological effectiveness (RBE) describes how much biological damage a given dose of an agent causes compared with a reference.
The term is used mainly for ionising radiation: different kinds of radiation (alpha, neutrons, X-rays) cause different amounts of damage for the same energy absorbed.
As per the answer key, the cause of such damage is taken as pollution (radioactive and other pollutants).
(The term relative biological effectiveness strictly refers to radiation, so radiation is also a strong candidate.)
So, as per the answer key, the answer is pollution.