Day-749 | Daily MCQs | UPSC Prelims | ENVIRONMENT AND ECOLOGY

Answer: A
Explanation:
About Sea Horse: It is a fish species and not a mammal.

● Seahorses are tiny fish that are named for the shape of their head, which looks like the head of a tiny horse.
● There are around 36 seahorse species, which are found in tropical and temperate coastal waters where they swim upright among seaweed and other plants.
● A female seahorse lays dozens, sometimes hundreds, of eggs in a pouch on the male seahorse’s abdomen. Called a ‘brood pouch’, it’s a bit like the pouch of a kangaroo, used for carrying young. Depending on the seahorse species, the eggs remain in the brood pouch for up to 45 days, until the eggs are ready to hatch. Unlike kangaroos, though, baby seahorses do not return to the pouch.
● Feeding on small crustaceans, seahorses are super-skilled ambush predators. Rather than chasing their food, they wait, unnoticed, for prey to pass by. They then suck their unsuspecting victim though their tube-like mouth, before swallowing it whole.
● A master of camouflage, these fab fish can be incredibly difficult to spot.
About other faunal species mentioned in the options-
Nampdapha flying squirrel
● Mammal listed as ‘Critically Endangered’ as per the IUCN’s Red list.
● Rare species of flying squirrel native to India.
● Restricted to Namdapha National Park in Arunachal Pradesh.
● Nocturnal species found along streams of dry deciduous montane forests.
● Flying squirrels are not capable of flight like birds or bats; instead, they glide between trees.
Kondana rat
● Mammal having IUCN Status of ‘Endangered’.
● Nocturnal burrowing rodent found only in Pune, Maharashtra.
● Habitat- Tropical and subtropical Dry Deciduous Forests.
Pygmy Hog
● Mammal
● IUCN Status- Endangered
● World’s smallest wild pig species.
● Indicator of the health of grassland habitat.
● Habitat- only in the Manas Wildlife Sanctuary of Assam.
● Once found along a narrow strip of tall and wet grassland plains on the Himalayan foothills – from Uttar Pradesh to Assam, through Nepal’s terai areas and Bengal’s duars – it was thought to have become extinct in the 1960s. But in 1971 it was “re-discovered” with a small population in the Barnadi Wildlife Sanctuary.
● Pygmy hogs are omnivores. They feed on roots, tubers, insects, rodents, and small reptiles.

Answer: B
Explanation: Greenhouse gases warm the earth by absorbing energy and decreasing the rate at which the energy escapes the atmosphere. These gases differ in their ability to absorb energy, that is, they have various radiative efficiencies. They also differ in their atmospheric residence times. Each gas has a specific global warming potential (GWP), which allows comparisons of the amount of energy the emissions of 1 ton of a gas will absorb over a given time period, usually a 100-year averaging time, compared with the emissions of 1 ton of CO2.

Answer. C
Explanation- Ketoprofen and Aceclofenac are two veterinary drugs which have been banned recently by the government in India due to the likely risks posed to the vultures. These are non-steroidal anti-inflammatory drugs (NSAIDs) used for the treatment of livestock animals.
Studies show that Aceclofenac gets metabolised into Diclofenac and Ketoprofen is toxic to Gyps Vultures.
India has banned Diclofenac in the year 2006 due to its adverse effect on the vulture species. Diclofenac is a veterinary drug used for pain management in livestock which was held as the main cause of the near wipe-out of vultures, who were eating such carrion and then suffering kidney failure almost within 24 hours.
India is home to nine species of vultures. Out of these, six species are resident (white–rumped vulture, Indian vulture, slender-billed vulture, red-headed vulture, bearded vulture and Egyptian vulture) and three species are migratory (cinereous vulture, griffon vulture and Himalayan vulture).

Answer. A
Explanation-
Statement 1 is correct- The Intergovernmental Panel on Climate Change (IPCC) was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988. The IPCC is an organization of governments that are members of the United Nations or WMO. The IPCC currently has 195 members.
Statement 2 is incorrect- IPCC does not have its own scientific panel, rather its work is the cumulative contribution of volunteers from across the world. For the assessment reports, experts volunteer their time as IPCC authors to assess the thousands of scientific papers published each year to provide a comprehensive summary of what is known about the drivers of climate change, its impacts and future risks, and how adaptation and mitigation can reduce those risks. An open and transparent review by experts and governments around the world is an essential part of the IPCC process.
Statement 3 is incorrect- Since 1988, the IPCC has had five assessment cycles and delivered five Assessment Reports, the most comprehensive scientific reports about climate change produced worldwide.
● In 1990, the First IPCC Assessment Report (FAR) underlined the importance of climate change as a challenge with global consequences and requiring international cooperation. It played a decisive role in the creation of the UNFCCC.
● The Second Assessment Report (SAR) (1995) provided important material for governments to draw from in the run-up to adoption of the Kyoto Protocol in 1997.
● The Third Assessment Report (TAR) (2001) focused attention on the impacts of climate change and the need for adaptation.
● The Fourth Assessment Report (AR4) (2007) laid the ground work for a post-Kyoto agreement, focusing on limiting warming to 2°C.
● The Fifth Assessment Report (AR5) was finalized between 2013 and 2014. It provided the scientific input into the Paris Agreement.

Answer. B
Explanation:
Statement 1 is incorrect- The Genetic Engineering Appraisal Committee (GEAC) is the statutory committee constituted under the “Rules for the Manufacture, Use/Import/Export and Storage of Hazardous Micro Organisms/Genetically Engineered Organisms or Cells (Rules, 1989)” framed under Environment (Protection) Act, 1986. Applications are considered by GEAC as per the provisions of the Rules, 1989 and amendments thereafter.
Statement 2 is correct- Clearance of Genetic Engineering Appraisal Committee (GEAC) is mandatory for the environmental release of Genetically Modified (GM) crops. As per the ‘’Rules 1989’, State/UT Biotechnology Coordination Committees and District Level Committees are responsible for monitoring instances of illegal cultivation of GM crops and taking appropriate action under Environment (Protection) Act, 1986.
Additional Information-
● GEAC is chaired by the Special Secretary/Additional Secretary of MoEF&CC and co-chaired by a representative from the Department of Biotechnology (DBT). Presently, it has 24 members and meets every month to review the applications.
● Bt Cotton is the only commercially approved crops in India.

Answer. B
Explanation- Options 1 and 3 are correct.
Initiatives of the World Bank in the field of environment are as follows-
Forest Carbon Partnership Facility
● The Forest Carbon Partnership Facility (FCPF) is a global partnership of governments, businesses, civil society, and indigenous people’s organizations focused on reducing emissions from deforestation and forest degradation, forest carbon stock conservation, the sustainable management of forests, and the enhancement of forest carbon stocks in developing countries, activities commonly referred to as REDD+.
● Launched in 2008, the FCPF now works with 47 developing countries across Africa, Asia, and Latin America and the Caribbean, along with 17 donors that have made contributions and commitments totalling $1.3 billion.
● Indonesia has become the first country in the East Asia Pacific region to receive payments through the World Bank’s FCPF.
BioCarbon Fund Initiative for Sustainable Forest Landscape
● It is a multilateral fund, supported by donor governments and managed by the World Bank.
● It promotes reducing greenhouse gas emissions from the land sector, including efforts to reduce deforestation and forest degradation in developing countries (REDD+), sustainable agriculture, as well as smarter land-use planning, policies and practices.
● The ISFL currently supports programs in Colombia, Ethiopia, Indonesia, Mexico, and Zambia.
About Greenhouse Gas Protocol-
● Greenhouse Gas Protocol is a joint initiative of World Resources Institute (WRI) and World Business Council for Sustainable Development (WBCSD).
● Greenhouse Gas Protocol provides accounting and reporting standards, sector guidance, calculation tools and training for businesses and local and national governments.
● It has created a comprehensive, global, standardized framework for measuring and managing emissions from private and public sector operations, value chains, products, cities and policies to enable greenhouse gas reductions across the board.

Answer. B
Explanation- Aquaponics is an integrated production of fish and hydroponic crops with recirculation of the nutrient solution in which fish wastes are used as plant fertilizers. It is a technique of mixing aquaculture (raising aquatic animals such as snails, crayfish, snails, fish, or prawns in tanks) with hydroponics in a symbiotic environment.
Aquaponics is a simple, promising and sustainable food production technology, especially in developing countries and arid zones, where resources are limited, freshwater is scare, and populations are increasing.
Statement 1 is correct- Tilapia is the fish species most commonly cultured in aquaponic systems. Although some aquaponic systems have used channel catfish, largemouth bass, crappies, common carp, koi carp, goldfish, Asian seabass, and Murray cod.
Statement 2 is correct- Almost all plants can be grown in aquaponics. However, plants also have different nutrient, space, and light requirements. Choosing the best plants to grow in your aquaponics system is essential for the system’s overall success. Until the new system is fully established, one must avoid planting nutrient-hungry plants like tomatoes and rather, stick to easy-to-grow plants like leafy greens, lettuce, and herbs.
Statement 3 is incorrect- A major concern in aquaponics is the removal of ammonia, the fish waste. Ammonia will accumulate and reach a toxic level unless it is removed by the process of nitrification or biofiltration in which ammonia is oxidised first to nitrite, which is toxic, and then to nitrate, which is relatively non-toxic. Two groups of naturally occurring bacteria such as Nitrosomonas and Nitrobater mediate this two-step process. The nitrates are then taken up the hydroponic plants grown in the aquaculture system.
Nitrification efficiency is affected by pH. The optimum pH range for nitrification is 7.0 to 9.0. Essential nutrients such as iron, manganese, copper, copper, zinc and boron are less available to plants at pH higher than 7.0 while the solubility of phosphorous, calcium, magnesium and molybdenum sharply decreases at a pH lower than 6.0.
Ammonification is the process by which microorganisms present in soil, sediment, or water mineralize low molecular weight, dissolved, organic molecules presenting amine or amide groups (of general formula R-NH2) and produce ammonium (NH4+).

Answer. D
Explanation-
Statement 1 is incorrect- The International Whaling Commission (IWC) is an independent intergovernmental body (not under the aegis of UNEP). It was set up under the International Convention for the Regulation of Whaling which was signed in Washington D.C. on 2nd December 1946.
The preamble to the Convention states that its purpose is to provide for the proper conservation of whale stocks and thus make possible the orderly development of the whaling industry. Following considerable debate, a commercial whaling moratorium was adopted in 1982 and came into full force in 1986.
The IWC is responsible for setting catch limits for commercial whaling (with the exceptions of Norway and Iceland, see below). The Commission receives advice on sustainability from its Scientific Committee before deciding catch limits, which are then set out in a document called the Schedule to the International Convention for the Regulation of Whaling.
An integral part of the Convention is its legally binding ‘Schedule.’ The Schedule sets out specific measures that the IWC has collectively decided are necessary in order to regulate whaling and conserve whale stocks.
These measures include catch limits (which may be zero as it the case for commercial whaling) by species and area, designating specified areas as whale sanctuaries, protection of calves and females accompanied by calves, and restrictions on hunting methods.
Statement 2 is incorrect- The legal framework of the IWC is the International Convention for the Regulation of Whaling which recognises three different types of whaling: commercial, aboriginal subsistence and special permit (also known as scientific) whaling. It regulates only commercial whaling and aboriginal subsistence whaling. Special permit whaling(for scientific purposes) is not regulated by the Commission but by national governments, although none currently undertake this type of whaling.
The Commission continues to regulate Aboriginal Subsistence Whaling, which is conducted by indigenous communities, often in remote parts of the world.
Statement 3 is incorrect- While India has been a member of the IWC since 1981, Japan joined it in 1951. However, Japan quit the IWC in 2019 as it began commercial whaling which is regulated by the IWC. As a non-member of the IWC, the International Convention for the Regulation of Whaling is no longer applicable on Japan.

Answer. B
Explanation-
Statement 1 is incorrect- Keystone species and foundation species are not synonymous. A keystone species is a plant or animal that plays a unique and crucial role in the way an ecosystem functions. Without keystone species, the ecosystem would be dramatically different or cease to exist altogether. All species in an ecosystem, or habitat, rely on each other. The contributions of a keystone species are large compared to the species’ prevalence in the habitat. A small number of keystone species can have a huge impact on the environment.
A keystone species’ disappearance would start a domino effect. Other species in the habitat would also disappear and become extinct. The keystone species’ disappearance could affect other species that rely on it for survival. For example, the population of deer or rabbits would explode without the presence of a predator. The ecosystem cannot support an unlimited number of animals, and the deer soon compete with each other for food and water resources. Their population usually declines without a predator such as a mountain lion.
In addition to keystone species, there are other categories of species that are crucial to their ecosystems’ survival.
● Foundation species play a major role in creating or maintaining a habitat that supports other species. Corals are one example of a foundation species in many islands. Corals produce the reef structures on which countless other organisms, including human beings, live.
Statement 2 is correct- Generally, carnivores act as keystone species in an ecosystem. The concept of keystone species was first introduced by Robert T. Paine in 1969. Paine studied a community of organisms that inhabited the intertidal zone along Washington’s Pacific coast. He found that one species, the carnivorous starfish (Pisaster ochracceus), played a key role in maintaining the balance of all other species in the community.
Large carnivores such as Mountain Lions, Wolves, Bears, Coyotes, Tiger, Cheetah etc. are the good examples for keystone species. A keystone species is often, but not always, a predator.
Herbivores can also be keystone species. For instance, elephants are a keystone species. Elephants eat small trees, such as acacia, that grow on the savanna. Even if an acacia tree grows to a height of several feet, elephants are able to knock over the tree and uproot it. This feeding behavior keeps the savanna a grassland and not a forest or woodland.

Answer. D
Explanation- The freshwater ecosystems are generally classified into two major groups as, lentic and lotic ecosystems.
Statement 1 is incorrect- The term ‘Lentic ecosystems’ is given to standing water bodies or still water bodies. Examples include lakes, ponds, swamps and bogs.
Statement 2 is incorrect- The term ‘lotic ecosystem’ is given to the flowing water bodies. Examples include all flowing water bodies like river, springs, creek.
Additional information-
● The subject of study of freshwater ecosystems is known as limnology.
● Almost all ecological factors like temperature, light, pH, dissolved gases, dissolved salts in water, turbidity, alkalinity, depth and areal distribution, all of these parameters play an active role in controlling the habitat of aquatic ecosystems.

Answer. B
Explanation- Biosphere reserves are sites established by countries and recognized under UNESCO’s Man and the Biosphere (MAB) Programme to promote sustainable development based on local community efforts and sound science. The programme of Biosphere Reserve was initiated by UNESCO in 1971.
Statement 1 is incorrect- Biosphere Reserve (BR) is an international designation by UNESCO for representative parts of natural and cultural landscapes extending over large area of terrestrial or coastal/ marine ecosystems or a combination thereof.
● BRs are designated to deal with one of the most important questions of reconciling the conservation of biodiversity, the quest for economic and social development and maintenance of associated cultural values.
● BRs are thus special environments for both people and the nature and are living examples of how human beings and nature can co-exist while respecting each other’s needs.
The Indian National MAB Committee under the MoEF&CC identifies and recommends potential sites for designation as biosphere reserves, following UNESCO’s guidelines and criterion. The Government of India provides financial assistance in a 90:10 ratio to the Northeastern States and 3 Himalayan States while other states are given financial assistance in the ratio of 60:40, for maintenance, improvement and development of biosphere reserves.
Statement 2 is correct- There are three zones carves out for the management and regulation of Biosphere reserves in India:
1. Core Area:
● It is the innermost, most protected area of a biosphere reserve. It may contain endemic plants and animals. Core areas often conserve the wild relatives of economic species and also represent important genetic reservoirs having exceptional scientific interest.
● A core zone is a protected area, like a National Park or Sanctuary/protected/regulated mostly under the Wildlife (Protection) Act, 1972.
● It is kept free from human interference.
● In the core or natural zone, human activity is strictly prohibited.
● However, scientific research is permitted within the core area.
● They conserve the wild relatives of economic species and also represent important genetic reservoirs having exceptional scientific interest.
2. Buffer Zone:
● The buffer zone surrounds the core zone, and its activities are managed in this area in ways that help in the protection of the core zone in its natural condition.
● It includes restoration, limited tourism (recreation), fishing, grazing, etc., which are permitted to reduce its effect on the core zone. Thus, limited human activity is allowed in the buffer zone.
● Research and educational activities are to be encouraged.
3. Transition Zone:
● It is the outermost part of the biosphere reserve.
● It is the zone of cooperation where human ventures and conservation are done in harmony.
● It includes settlements, croplands, managed forests and areas for intensive recreation and other economic uses characteristics of the region.

Answer. A
Explanation-
Statement 1 is correct- London smog and photochemical smog are two different concepts in ecology. Photochemical smog, also known as Los Angeles smog, is a secondary pollutant.
London smog: Also known as sulphurous smog or classical smog, London smog is majorly the result of high concentration of sulphur dioxide in the air. The necessary ingredients and the conditions for the development of classical smog or London smog are as follows.
1. Primary pollutants- sulphur dioxide and soot particles
2. Secondary pollutants – H2SO4, sulphate aerosols, etc.
3. Radiation temperature inversion
4. High relative humidity and usually foggy
5. Low temperature (< 35 degrees Fahrenheit). The Great Smog of 1952, also known as the London Smog Event, is perhaps the most well-known example of a severe air pollution event that was cause by meteorological conditions. In December of 1952, a prolonged period of very cold weather combined with windless conditions resulted in the anticyclone settling over London. This created a temperature inversion with cool air trapped near the surface over the city of London, England, along with an accumulation of coal combustion products. Statement 2 is correct and explains statement 1- Photochemical smog is a brownish-grey haze caused by the action of solar ultraviolet radiation on atmosphere polluted with hydrocarbons and oxides of nitrogen. It contains anthropogenic air pollutants, mainly ozone, nitric acid, and organic compounds(hydrocarbons), which are trapped near the ground by temperature inversion. Thus, formation of photochemical smog is a common pollution-related concern in dense metropolitans on warm sunny days.

Answer. A
Explanation- Statements 1 and 2 are correct. Statement 2 explains statement 1:
Biogeochemical cycles are intricate processes that transfer, change and store chemicals in the geosphere, atmosphere, hydrosphere, and biosphere. The term biogeochemical cycles express the interactions among the organic (bio-) and inorganic (geo-) worlds, and focuses on the chemistry (chemical-), and movement (cycles) of chemical elements and compounds. In its simplest form, cycling describes the movement of elements through various forms and their return to their original state.
Biogeochemical cycles can be classed as gaseous, in which the reservoir is the air or the oceans (via evaporation), and sedimentary, in which the reservoir is the Earth’s crust. Gaseous cycles include those of nitrogen, oxygen, carbon, and water; sedimentary cycles include those of iron, calcium, phosphorus, and other more earthbound elements.
In a sedimentary cycle, elements move from land to water to sediment. Main reservoirs are the soil and sedimentary rocks. Each cycle basically has a solution phase and a rock phase. Weathering releases minerals from the Earth’s crust in the form of salts, some of which dissolve in water, pass through a series of organisms, and ultimately reach the deep seas, where they settle out of circulation indefinitely. Other salts deposit out as sediment and rock in shallow seas, eventually to be weathered and recycled.
For example, phosphorus (P) enters the biosphere almost entirely from the soil through absorption by plant roots. Weathering of rocks containing phosphate minerals results in the relatively small pool of inorganic phosphorus available for use by organisms. In most soils, the major amount of phosphorus absorbed by plants comes from organic molecules that undergo decomposition releasing phosphorus in plant‐available inorganic forms.

In a gas cycle, elements move through the atmosphere and the main reservoirs are the atmosphere and the ocean. The cycling of oxygen, nitrogen, water vapor, and carbon dioxide, as well as the trace gases— methane, ammonia, various oxides of nitrogen and sulphur, and non-methane hydrocarbons—between the atmosphere and the biosphere results in relatively constant proportions of these compounds in the atmosphere over time.

Answer. A
Explanation-
Both the species benefit in mutualism, and both lose in competition in their interactions with each other.
In many species of fig trees, there is a tight one-to-one relationship with the pollinator species of wasp. It means that a given fig species can be pollinated only by its ‘partner’ wasp species and no other species. The female wasp uses the fruit not only as an oviposition (egg-laying) site but uses the developing seeds within the fruit for nourishing its larvae. The wasp pollinates the fig inflorescence while searching for suitable egg-laying sites. In return for the favour of pollination the fig offers the wasp some of its developing seeds, as food for the developing wasp larvae.
Other examples of mutualism are as follows:
● Lichens represent an intimate mutualistic relationship between a fungus and photosynthesising algae or cyanobacteria.
● Similarly, the mycorrhizae are associations between fungi and the roots of higher plants. The fungi help the plant in the absorption of essential nutrients from the soil while the plant in turn provides the fungi with energy-yielding carbohydrates.
About other biotic interactions:
● In both parasitism and predation, only one species benefits (parasite and predator, respectively) and the interaction is detrimental to the other species (host and prey, respectively).
● The interaction where one species is benefitted and the other is neither benefitted nor harmed is called commensalism.
● In amensalism, on the other hand, one species is harmed whereas the other is unaffected.
● Predation, parasitism and commensalism share a common characteristic– the interacting species live closely together.

Answer. C
Explanation:
Persistant Organic Compounds (POPs) are organic compounds that to a varying degree, resist photolytic, biological and chemical degradation. The most commonly encountered POPs are organochlorine pesticides such as DDT, industrial chemicals most notably polychlorinated biphenyls (PCB) as well as unintentional by-products of many industrial processes, especially polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF), commonly known as ‘dioxins’. These toxic coumpounds are persistent in the environment and are able to last for several years before breaking down.
Statement 1 is correct- POPs bioaccumulate in individual organisms at each trophic level and biomagnify in succeeding trophic levels. As one moves up the food chain, concentrations of POPs tend to increase (biomagnify) such that animals at the top of the food chain (at higher trophic levels) such as fish, predatory birds, mammals and humans tend to have the greatest concentrations of these chemicals and therefore, are the highest risk from acute and chronic toxic effects. This leads to health concerns such as cancer, reproductive disorders, weak immune system, neuro-behavioural impairment, endocrine disruption, genotoxicity and increased birth defects.
Statement 2 is incorrect- POPs are often halogenated and characterised by low water solubility but high lipid solubility which facilitates the bioaccumulation and biomagnification of POPs in the fatty tissues. Thus, they are characterised as being lipophilic. In fatty tissues, the concentration of POPs can biomagnify by upto 70,000 times higher than the background levels.

Answer. D
Explanation- Contaminated water is responsible for various ailments in human beings.
Statement 1 is incorrect- Long-term exposure to arsenic causes Blackfoot disease (BFD), a form of peripheral vascular disease. The groundwater contamination with arsenic is responsible for such diseases in humans.
● Arsenic is introduced into soil and groundwater during weathering of rocks and minerals followed by subsequent leaching and runoff.
● It can also be introduced into soil and groundwater from anthropogenic sources.
● Arsenic is emitted into the atmosphere by high-temperature processes such as coal-fired power plants, burning vegetation and volcanism.
● In water, particularly groundwater, where there are sulfide mineral deposits and sedimentary deposits deriving from volcanic rocks, the concentrations can be significantly elevated.
● Natural low temperature biomethylation and reduction to arsines also releases arsenic into the atmosphere.
Statements 2 is incorrect- Cadmium is a metal used in batteries, solar cells, alloys, pigments, and more. Cadmium poisoning occurs when someone ingests or inhales contaminated food, water, or air. Long-term exposure to cadmium is responsible for diseases like Itai-Itai.
Itai-itai disease is characterized by osteomalacia, osteoporosis, renal tubular dysfunction, malabsorption, and anaemia. Because of the severe pain, it is also called ouch-ouch disease.
Water rarely contains toxic levels of cadmium unless there is a direct contamination source such as industrial wastewater or hazardous waste dumping.
Other sources of cadmium include:
● Phosphate fertilizers
● Sewage sludge
● Batteries
● Plating
● Plastics
● Pigments
● Burning of fossil fuels
Additional information-
● Minamata disease is caused by Methyl Mercury.
● Blue baby syndrome or Methemoglobinemia is caused by excessive nitrate contamination in groundwater.

Answer. D
Explanation-
Statement 1 is incorrect- Kigali Amendment to Montreal Protocol emphasises on gradually reduce the consumption and production of hydrofluorocarbons (HFCs) and not HCFCs.
● The Parties to the Montreal Protocol reached an agreement at their 28th Meeting of the Parties on 15 October 2016 in Kigali, Rwanda to phase down HFCs.
● Countries agreed to add HFCs to the list of controlled substances and approved a timeline for their gradual reduction by 80-85 per cent by the late 2040s.
● Hydrofluorocarbons (HFCs) were introduced as non-ozone depleting alternatives to support the timely phase-out of CFCs and HCFCs.
● HFCs are now widespread in air conditioners, refrigerators, aerosols, foams and other products.
● While these chemicals do not deplete the stratospheric ozone layer, some of them have high Global Warming Potentials (GWP) ranging from 12 to 14,000.
The issue of phase out of HCFC along with other ozone depleting substances such as Chlorofluorocarbons (CFCs), halons, Carbon tetrachloride (CCl4), Methyl chloroform (CH3CCl3), Hydrobromofluorocarbons (HBFCs) and Methyl bromide (CH3Br) was raised in Montreal Protocol of 1987.
● It was designed to stop the production and import of ozone depleting substances and reduce their concentration in the atmosphere to help protect the earth’s ozone layer.
● The Montreal Protocol sits under the Vienna Convention for the Protection of the Ozone Layer (the Vienna Convention).
● The Vienna Convention was adopted in 1985 following international discussion of scientific discoveries in the 1970s and 1980s highlighting the adverse effect of human activity on ozone levels in the stratosphere and the discovery of the ‘ozone hole’.
Statement 2 is correct- Hydrochlorofluorocarbons (HCFCs) are gases used worldwide in refrigeration, air-conditioning and foam applications, but they are being phased out under the Montreal Protocol since deplete the ozone layer. HCFCs are both Ozone Depleting Substances (ODS) and powerful greenhouse gases: the most commonly used HCFC is nearly 2,000 times more potent than carbon dioxide in terms of its global warming potential (GWP).

Answer. C
Explanation- Options 2, 3, 4 and 5 are correct.
Cloud seeding is a process of weather modification to change type of precipitation to attain cloud condensation. There are two principal cloud seeding techniques. Hygroscopic cloud seeding aims at speeding up droplet coalescence in liquid clouds, leading to production of large droplets that start to precipitate. Cloud seeding material consists usually of large salt particles dispersed by some means to the cloud base.
The idea of the other technique, glaciogenic cloud seeding, is to trigger ice production in supercooled clouds, leading to precipitation. Glaciogenic cloud seeding is usually done by dispersing efficient ice nuclei, such as silver iodide particles or dry ice (solid carbon dioxide) into the cloud, causing heterogeneous ice nucleation.
The following chemicals can be used for cloud seeding-
● Silver iodide
● Potassium iodide
● CO2 in the form of dry ice
● Propane
● Calcium carbide
● Ammonium nitrate
● Sodium chloride

Answer. D
Explanation-
Statement 1 is correct- Fly ash is a fine powder which is a byproduct from burning pulverized coal in thermal power plants. It is the principal industrial waste byproduct from the burning of solid fuels. FA is a powdery solid that is constituted mostly of unburned carbon (UC), metal oxides (Si, Fe, Ca, and Al), and other inorganic substances.
Statement 2 is correct- It contains substantial amounts of silicon dioxide (SiO2) (both amorphous and crystalline), aluminium oxide (Al2O3), Fe2O3 and calcium oxide (CaO), the main mineral compounds in coal-bearing rock strata.
Statement 3 is correct- Fly ash can be used as a soil ameliorate that may improve physical, chemical and biological properties of the degraded soils and is a source of readily available plant micro-and macro-nutrients. The high concentration of elements (K, Na, Zn, Ca, Mg and Fe) in fly ash increases the yield of many agricultural crops.
● Fly ash has been shown to act as a liming material to neutralize soil acidity and provide plant-available nutrients.
● Most of the fly ash produced in India is alkaline in nature; hence, its application to agricultural soils could increase the soil pH and thereby neutralize acidic soils.
Statement 4 is incorrect- Fly ash is a pozzolan, a substance containing aluminous and silicious material that forms cement in the presence of water. When mixed with water and lime, it forms a compound similar to Portland cement. Fly ash is considered to be a cost-effective substitute to Portland cement. It requires less water than Portland cement and it can be used with ease in cold weather.

Answer. A
Explanation:
Statement 1 is incorrect- Acid rain refers to any precipitation (rain, fog, snow, mist) that is more acidic than usual (pH< 5.6). The oxides of sulphur and nitrogen are responsible for causing acid rain. ● Rotting vegetation and erupting volcanoes release some chemicals that can cause acid rain, but most acid rain is a product of human activities. ● The biggest sources are coal-burning power plants, factories, and automobiles. ● When humans burn fossil fuels, sulphur dioxide (SO2) and nitrogen oxides (NOx) are released into the atmosphere. Those air pollutants react with water, oxygen, and other substances to form airborne sulfuric and nitric acid. Winds may spread these acidic compounds through the atmosphere and over hundreds of miles as dry deposition. ● When acid rain reaches Earth as wet deposition, it flows across the surface in runoff water, enters water systems, and sinks into the soil. Statement 2 is correct- The ecological effects of acid rain are most clearly seen in aquatic environments, such as streams, lakes, and marshes where it can be harmful to fish and other wildlife. As it flows through the soil, acidic rain water can leach aluminium from soil clay particles and then flow into streams and lakes. The more acid that is introduced to the ecosystem, the more aluminium is released. At pH 5, most fish eggs cannot hatch. At lower pH levels, some adult fish die. Statement 3 is incorrect- After a long period of acid rain, microbial species in the soil and water shift from bacteria-bound to fungi-bound, causing a microflora imbalance. This causes a delay in soil organic material breakdown and an increase in fungal disease in aquatic life and forests. Other impacts of acid rain- ● It promotes leaching of heavy metals like lead, mercury etc, which percolate into groundwater and affect soil microbiota/ fauna. ● Acid rain destroys marble and limestone.