UGC NET Paper 2: Environmental Science 5th Dec 2019 Shift 1 (Previous Year Paper)

The correct answer is Resilience.

Key Points

Therefore, the correct answer is resilience.

The correct answer is higher.

Key Points

• Ecotones are points along an environmental gradient where there is a sharp transition between two ecological communities, ecosystems, or ecological zones.
• Ecotones are found in many spatial sizes and can be either natural or created by humans.
• The abundance and richness of species tend to peak in ecotonal zones.
• They include transitions between broad biomes and ecoregions as well as mountain treelines (for example, Mediterranean and arid).
• There is evidence that ecotones may potentially serve as centres for the emergence of new species.
• Populations in ecotones may be more resilient to biotic invasions, invading species, and other environmental changes because they are potentially pre-adapted to changing settings.
• Due to their frequent modest spatial size, relatively higher levels of biodiversity, and populations that can adapt to change, ecotones may be a good candidate for conservation.

Therefore, the correct answer is higher.

The correct answer is Fog.

Key Points

Any product of the condensation of atmospheric water vapour that falls to the ground is referred to as precipitation.

Precipitation typically comes in the following forms:

1. Drizzle
2. Rain
3. Sleet
4. Snow
5. Graupel
6. Hail.

When a section of the atmosphere fills up with water vapour, the water condenses and "precipitates", causing precipitation to happen.

Because the water vapour does not enough condense to precipitate, fog and mist are instead suspensions rather than precipitation.

Therefore, the correct answer is Fog.

Explanation:

• La Nina is a Spanish word meaning "the girl" or "the little girl."
• It is also used to describe a climate pattern that affects the tropical Pacific Ocean.
• La Niña is the opposite of El Niño and is characterized by cooler-than-normal sea surface temperatures in the central and eastern tropical Pacific Ocean.
• La Niña episodes, which can last up to 12 months, are associated with an increased chance of below-average precipitation in the southwestern United States, including California and Arizona. La Niña episodes can also cause changes in temperature and precipitation patterns around the world.

The correct answer is greater than 1.

Key Points

• Fast breeder reactor (FBR) which uses fast (i.e. unmoderated) neutrons to breed fissile plutonium and possibly higher transuranic from fertile uranium-238.
• The fast spectrum is flexible enough that it can also breed fissile uranium-233 from thorium.
• One measure of a reactor's performance is the "conversion ratio", defined as the ratio of new fissile atoms produced to fissile atoms consumed.
• A breeder reactor is a nuclear reactor that generates more fissile material than it consumes i.e., the ratio of fissile material produced to fissile material consumed is greater than 1.
• When the conversion ratio is greater than 1, it is often called the "breeding ratio".

Therefore, the correct answer is greater than 1.

The correct answer is parallel to the strike of the fault plane.

Key Points

• A strike-slip fault, or a transform fault, is a fault in which movement is parallel to the strike of the fault plane.
• The opposite of a strike-slip fault is a dip-slip fault.
• A transform fault can be either left-lateral or right-lateral.
• It is determined by selecting one block as a reference and then examining the movement of the other with the referenced block.
• For instance, a left-lateral strike-slip fault means the block opposite from which one is standing moves left.
• A right-lateral transform fault means the block opposite from which one is standing is moving right.

Therefore, the correct answer is parallel to the strike of the fault plane.

The correct answer is 1250 m³.

Key PointsGiven:

• Total rainfall = 50 mm
• Time duration = 30 min
• Area = 2.5 ha

Important Points

• A rainfall of 1 mm supplies 0.001 m³ or 1 litre of water to each square metre of the field.
• Thus, 1 ha receives 10000 litres
• 1 ha = 10000 m²

So, 50 mm rainfall = 0.05 m³

       2.5 ha = 25000 m²

Therefore, the total volume of water that fell on that area during the rain would be 

0.05 × 25000 = 1250 m³

Therefore, the correct answer is 1250 m3.

The correct answer is eutrophication.

Key Points

• Eutrophication is characterized by excessive plant and algal growth due to the increased availability of one or more limiting growth factors needed for photosynthesis, such as sunlight, carbon dioxide, and nutrient fertilizers.
• Eutrophication occurs naturally over centuries as lakes age and is filled in with sediments.
• However, human activities have accelerated the rate and extent of eutrophication through both point-source discharges and non-point loadings of limiting nutrients, such as nitrogen and phosphorus, into aquatic ecosystems (i.e., cultural eutrophication), with dramatic consequences for drinking water sources, fisheries, and recreational water bodies.
• The known consequences of cultural eutrophication include blooms of blue-green algae (i.e., cyanobacteria), tainted drinking water supplies, degradation of recreational opportunities, and hypoxia.

The correct answer is eutrophication.

Additional Information

• A water body can be oligotrophic, mesotrophic, eutrophic, or hypereutrophic:

​Oligotrophic:

• An oligotrophic lake or water body has relatively low productivity due to the low nutrient content in the lake.
• The waters of these lakes are usually quite clear due to the limited growth of algae in the lake.
• The waters of such lakes are of high-drinking quality.
• Such lakes support aquatic species that require well-oxygenated, cold waters such as lake trout.

Mesotrophic:

• Lakes with an intermediate level of productivity are called mesotrophic lakes.
• These lakes have medium-level nutrients and are usually clear water with submerged aquatic plants.

Eutrophic:

• Eutrophic lakes have high levels of biological productivity.
• An abundance of plants is supported by such lakes due to the rich nutrient constitution, especially nitrogen and phosphorus.

Hypereutrophic:

• These lakes suffer from problems arising due to excessive plant and algal growth due to a high supply of growth nutrients.
• These lakes have little transparency due to the dense overgrowth of algae or aquatic flora.
• These lakes usually have visibility limited to lower than 3 feet.
• The overgrowth of algae often suffocates the fauna below the water depths and this might create dead zones beneath the surface of the water.

The correct answer is ~ 17.3 years.

Key Points

Given:

Rate of growth (r) = 4% per year 

The length of time required to double a quantity growing at r % is calculated as:

$t _d= {69.3\over r(\%)}$

$t _d= {69.3\over 4}$= 17.325 

Therefore, t_d = ~ 17.3 years

Explanation:

Artesian well:

• Artesian wells are the wells in which extraction of water is possible.
• An artesian well is dug into an artesian aquifer which is a confined aquifer containing groundwater under positive pressure(or pressure above atmospheric).
• Wells that tap these confined aquifers are "artesian wells". If the altitude that the pressurized aquifer pushes water up a well tapping it is the "piezometric level". If this level is below the land surface altitude, the water will not shoot out of the well at the land surface, hence the well is called an artesian well.
• But if the piezometric level is higher than the wellhead altitude at the land surface, the water will be pushed upward in the well and emerge at the land surface, with no pump needed. This kind of well is a flowing artesian well.
• Artesian wells have the highest specific yield of water.

Additional Information

Infiltration wells: 

• Infiltration wells are shallow wells constructed in series along the banks of a river, in order to collect the river water seeping through their bottoms.
• These wells are generally constructed of brick masonry with open joints. The water percolates through these joints and gets collected in these wells.
• The various infiltration wells are connected by porous pipes to a sump well called jack well.
• The water reaching the jack well from different infiltration wells is lifted, treated and distributed to the consumers.

Tube well:

• A tube well is a type of water well in which a long, 100–200 millimeters (3.9–7.9 in)-wide, stainless steel tube or pipe is bored into an underground aquifer. The lower end is fitted with a strainer, and a pump lifts water for irrigation.

Open Wells:

• Open wells are wells that have comparatively large diameters but low yields (or discharges) and are not very deep. The diameters of the open wells usually vary from 1m to 10m

The correct answer is 'Bioaugmentation'

Key Points

• Bioaugmentation:
• Bioaugmentation is a method of bioremediation that involves the addition of specifically cultured microorganisms to contaminated environments to accelerate the degradation of pollutants.
• This process leverages microbial strains that are capable of breaking down specific contaminants more efficiently than the indigenous microbial population.
• It is particularly useful in scenarios where native microorganisms are insufficient to remediate the contaminated site effectively.
• Bioaugmentation can be applied to both soil and water remediation projects, targeting various contaminants such as hydrocarbons, chlorinated solvents, heavy metals, and nutrients.
• The success of bioaugmentation depends on factors like the compatibility of the introduced microbes with the native environment and the presence of necessary nutrients and environmental conditions for microbial growth.

Additional Information

• Enhanced Bioremediation:
• Enhanced bioremediation involves the stimulation of native microbial activity through the addition of nutrients, oxygen, or other amendments to the contaminated environment.
• This approach does not necessarily involve the introduction of external microbial cultures; instead, it enhances the activity of existing microbes.
• Bioventing:
• Bioventing is a remediation technique that involves the controlled injection of air or oxygen into soil to increase the microbial degradation of pollutants, particularly volatile organic compounds (VOCs).
• It primarily focuses on aerobic degradation processes, enhancing the activity of native soil microorganisms.
• Intrinsic Bioremediation:
• Intrinsic bioremediation, also known as natural attenuation, relies on natural processes and the inherent capacity of native microbial populations to degrade contaminants without human intervention.
• This method is passive and relies on existing environmental conditions and microbial communities to gradually clean up the pollution.

Important Points

• For bioaugmentation to be successful, the introduced microbial cultures must survive, proliferate, and maintain their degradative capabilities in the new environment.
• This technique can be complemented by monitoring techniques to assess the effectiveness of the remediation process and environmental impact.
• Bioaugmentation is often used in conjunction with other bioremediation strategies to optimize the removal of contaminants.

The correct answer is 'removing toxic chemicals from the polluted ecosystem'

Key Points

• Phytoremediation:
• Phytoremediation is an environmental remediation technique that uses living plants to clean up soil, air, and water contaminated with harmful chemicals.
• This process exploits the natural abilities of plants to absorb, concentrate, and metabolize toxic substances through their roots and shoots.
• Phytoremediation is cost-effective, sustainable, and minimizes the need for more invasive and disruptive soil remediation methods.
• There are various types of phytoremediation including phytoextraction, phytostabilization, phytofiltration, and phytodegradation, each targeting different contaminants and conditions.
• Common plants used in phytoremediation include poplar trees, willows, sunflowers, and various grasses which are effective at extracting heavy metals and degrading organic pollutants.

Additional Information

• Improving the health of diseased plants:
• This option is incorrect because phytoremediation focuses on the cleanup of environmental pollutants rather than directly addressing the health of diseased plants.
• Improving plant health typically involves agricultural techniques, pest control, and other plant care practices.
• Removing dissolved oxygen from the aquatic ecosystem:
• This option is incorrect as phytoremediation does not involve the removal of dissolved oxygen from aquatic systems.
• Dissolved oxygen is crucial for aquatic life, and processes that affect its levels include eutrophication and hypoxia, not phytoremediation.
• Eradicating the invasive species:
• This option is incorrect because phytoremediation is not designed to target or remove invasive species.
• Eradicating invasive species involves different environmental management strategies such as biological control, manual removal, and chemical treatments.

Important Points

• The efficiency of phytoremediation can be influenced by factors like plant species, type of contaminant, soil properties, and climatic conditions.
• Phytoremediation is particularly effective for removing heavy metals, pesticides, solvents, and petroleum hydrocarbons from polluted sites.
• Advantages of phytoremediation include its aesthetic appeal, the potential for biomass production, and the enhancement of soil structure and fertility.
• Limitations involve the depth of root growth, the time required for remediation, and the potential for the harvested plant material to become hazardous waste itself.

The correct answer is Natural Gas.

Key Points

Therefore, the correct answer is Natural Gas.

Key Points

• The gross calorific value of a gas is the quantity of heat liberated by the combustion of a unit volume of gas.
• The net calorific value of a gas is the gross calorific value minus the latent heat in the water produced by the combustion of the hydrogen in the gas (free or combined) above atmospheric temperature.

The correct answer is Single basin with the linked operation.

Key Points

• The tidal power plants are generally classified based on the number of basins used for power generation.
• They are further subdivided into one-way or two-way systems as per the cycle of operation for power generation.

​

Single basin-one-way cycle:

• This is the simplest form of the tidal power plant.
• In this system, a basin is allowed to get filled during flood tide and during the ebb tide, the water flows from the basin to the sea passing through the turbine and generating power.
• The power is available for a short duration ebb tide.

Single-basin two-way cycle:

• In this arrangement, power is generated both during flood tide as well as ebb tide also.
• The power generation is also intermittent but the generation period is increased compared with a one-way cycle.
• However, the peak obtained is less than the one-way cycle.

Single–basin two-way cycle with pump storage:

• In this system, power is generated both during flood and ebb tides.
• Complex machines capable of generating power and pumping the water in either direction are used.
• A part of the energy produced is used for introducing the difference in the water levels between the basin and sea at any time of the tide and this is done by pumping water into the basin up or down.
• The period of power production with this system is much longer.

Double basin type:

• In this arrangement, the turbine is set up between the basins.
• One basin is intermittently filled with the tide and the other is intermittently drained by the ebb tide.
• Therefore, a small capacity but continuous power is made available with this system.
• The main disadvantages of this system are that 50% of the potential energy is sacrificed in introducing the variation in the water levels of the two basins.

Double basin with pumping:

• In this case, off-peak power from the base load plant in an interconnected transmission system is used either to pump the water up the high basin.
• The net energy gain is possible with such a system if the pumping head is lower than the basin-to-basin turbine generating head.

Therefore, the correct answer is a Single basin with the linked operation.

The correct answer is 76.6 W/m2.

Key PointsGiven:

Speed of wind, v = 5 m/s

The density of air, ρ = 1.266 J/kg.K/m³

Area , A = 1

Using the formula:

$P = {1\over2}\rho AV^3$ 

$P = {1\over2}\times 1.226\times(5)^3$ = 76.625

Therefore, Power, P = 76.6 W/m2

The correct answer is ~59%.

Key PointsTheoretical maximum wind power:

• The air density is proportional to the air temperature and the air pressure, both of which vary with height above sea level.
• The power in the wind cannot be completely converted to the mechanical energy of a wind turbine.
• The losses due to friction reduce the actual wind power.
• The theoretical maximum of energy extraction from wind was calculated by Betz in 1926.
• The power output from the wind turbine is given as follows:
• P_T = ¼ A₁ x ρ x (μ_o² - μ₂² ) x (μ_o+μ₂)
• The power output depends on outlet velocity μ₂, hence for the maximum output dPT/dμ₂ = 0
• And so μ₂ = -μ₁, which is impossible μ₂ = μ₁/3
• Substituting μ₂ = μ₁/3 in the above equation, then
• PT =8/27 ρ x A x μ₀³= 16/27 [1/2 x ρ x A x μ₀³ ]
• = 16/27 x P_w
• = 59.3% x Pw
• As per Betz's theory, a wind turbine can utilize only 59% of the wind power even if no losses have occurred and so the power is multiplied by a factor of 0.59.
• Thus, the theoretical maximum fraction of power in the wind that can be extracted by a horizontal axis wind turbine is 59%.

Therefore, the correct answer is ~59%

The correct answer is They decompose and metabolize slowly.

Key Points Organophosphates:

• Organophosphates are chemical substances produced by the process of esterification between phosphoric acid and alcohol.
• Organophosphates can undergo hydrolysis with the liberation of alcohol from the ester bond.
• These chemicals are the main components of herbicides, pesticides, and insecticides.
• Acute or chronic exposure to organophosphates can produce varying toxicity levels in humans, animals, plants, and insects.
• Organophosphates are classified as non-persistent pesticides.
• They do not bioaccumulate appreciably in humans and are rapidly metabolized and excreted in the urine.
• They are rapidly broken down into other chemicals so they do not build up in the environment.
• They are not likely to build up to high or dangerous levels in animal or plant foods that you might eat.
• Long-term exposure to organophosphates can cause confusion, anxiety, loss of memory, loss of appetite, disorientation, depression, and personality changes.
• Examples: Parathion, Chlorpyrifos, Diazinon, Dichlorvos, Phosmet, Fenitrothion, Tetrachlorvinphos, Azamethiphos etc.

Therefore, the correct answer is they decompose and metabolize slowly.

The correct answer is Polycyclic Aromatic Hydrocarbons.

Key Points

Photochemical smog:

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

Primary pollutants:

• The two major primary pollutants, nitrogen oxides and VOCs combine to change in sunlight in a series of chemical reactions, to create what is known as secondary pollutants.

Secondary pollutants:

• The secondary pollutant that causes the most concern is the ozone that forms at ground level.
• While ozone is produced naturally in the upper atmosphere, it is a dangerous substance when found at ground level.
• Many other hazardous substances are also formed, such as peroxyacetyl nitrate (PAN).

Pollutants involved in photochemical smog:

• Nitrogen oxides
• Volatile organic compounds (VOCs)
• Ozone
• Peroxyacetyl nitrate (PAN)
• Peroxy Benzoyl Nitrate (PBN)

Therefore, the correct answer is Polycyclic Aromatic Hydrocarbons.

The correct answer is Lofting.

Key Points Lofting:

• When the lapse rate is super adiabatic (unstable) above the emission source and inversion conditions (stable) exist below the source, the plume is said to be lofting.
• When the pollutants are emitted above the inversion layer, they are dispersed vigorously in the upward direction since the top of the inversion layer acts as a barrier to the movement of pollutants towards the ground.
• Lofting is the most favourable plume type as far as ground-level concentrations are concerned and one of the major goals of tall stack operations.

Therefore, the correct answer is lofting.

The correct answer is ~ 3 dB per doubling of distance from the source.

Key Points

The sound pressure level at a certain location when sound is emitted from a line source is calculated using the formula:​

$L_2 = L_1-[{10\log {r_2\over r_1}}]$

  ​Where, 

​L₁ = Sound pressure level at a location 1 (dB)

L₂ = Sound pressure level at a location 2 (dB)

r₁ = Distance between source and location 1 

r₂ = Distance between source and location 2

 If r₂ is 2r₁, then, 

​$L_2 = L_1-[{10\log {2\over 1}}]$

$L_2 = L_1-[{10\log {2}}]$

$L_2 - L_1= [{10\times 0.301}]$

L₂ - L₁ = 3 dB

Thus, for every doubling of distance, there is a reduction of 3 dB.

Therefore, the correct answer is ~ 3 dB per doubling of distance from the source.

The correct answer is Cyclone.

Key Points

Therefore, the correct answer is Cyclone.

The correct answer is Yellow.

Key Points

According to Biomedical Waste Management Rules 2016, the following are the different biomedical waste categories and the type of waste they contain:

Therefore, the correct answer is Yellow.

The correct answer is Psychrophiles.

Key Points

• Psychrophilic microorganisms are called cold-loving microbes.
• They live in permanently cold environments such as polar regions and the deep sea.
• ​​Examples: Pseudoalteromonas, Moraxella, Psychrobacter, Flavobacterium, etc.
• ​Mesophilic microorganisms are called moderate temperature-loving microbes.
• Mesophiles in the bacteria domain can be either gram-positive or gram-negative.
• Their oxygen requirements can be aerobic or anaerobic. 
• Examples: Escherichia, Klebsiella, Aeromonas and Alcaligenes, Enterococcus etc.
• Thermophilic microorganisms are called heat-loving microbes.
• They can be found in various geothermally heated areas of the Earth, including hot springs found in Yellowstone National Park and deep-sea hydrothermal vents, as well as decaying plant matter like peat bogs and compost.
• Examples: Lactobacilli, Streptococcus thermophilus, bifidobacteria, etc.
• Acidophiles are organisms that grow at an optimum pH below 3–4.
• These are a diverse group of organisms including archaea, bacteria, fungi, algae, and protozoa growing in acidic conditions, reported from natural environments like solfataric fields, sulfuric pools, and geysers.
• Examples: Acidianus, Desulfurococcus, Sulfolobus, Thermoplasma, Acidobacterium, Leptospirillum, Ferroplasma etc.

Therefore, the correct answer is Psychrophiles.

The correct answer is the 42nd amendment.

Key Points Article 48(A):

• Within quintuple years of the Stockholm Declaration, the Constitution of India was amended to incorporate protection and improvement of the environment as a constitutional mandate.
• And the Constitution was amended by the 42^nd amendment in 1976 and by these amendments directive principles of State policy have been introduced in Article 48A.
• It comes under the directive principles of State policy.
• It says that the State shall endeavour to protect and improve the environment and safeguard the forests and wildlife of the country.
• The article imposed a duty on the State to guard the environment against pollution by adopting various measures.
• The general people of the country have a fundamental right to a sustaining, virtuous and clean-living environment.
• The Constitution of India, in terms of Article 48A, mandates that the state is under a constitutional obligation to safeguard and develop the environment and to safeguard the forest, jungle and wildlife in the country.
• By the 42^nd amendment to the Constitution, the Parliament, with the object of sensitizing the citizens to their duty, incorporated Article 51A in the Constitution.

Therefore, the correct answer is the 42nd amendment.

The correct answer is Gujrat Fluorochemicals Ltd.

Key Points

• The clean development mechanism was created to be a practical solution for lowering the carbon emissions of industrialised nations.
• The Kyoto Protocol, which was established following the establishment of the United Nations Framework Convention on Climate Change, contains this method.
• Gujarat Fluorochemicals Ltd (GFL), headquartered in Vadodara, India, is the first company in India and one of only three worldwide to have a CDM project for emissions reductions certified following evaluation by the esteemed UNFCCC Executive Board.

Therefore, the correct answer is Gujrat Fluorochemicals Ltd.

The correct answer is the cases in which offences are made by authorities.

Key Points

• The Forest (Conservation) Act of 1980 is an act by the Parliament of India which ensures the conservation of forests and their resources.
• It was enacted by the Parliament of India to control the ongoing deforestation of the forests of India.
• It came into force on October 25, 1980, containing five sections.

 Section 3B: Offences by the Authorities and Government Departments. 

• Where any offence under this Act has been committed -

1. by any department of Government, the head of the department; or
2. by any authority, every person who, at the time the offence was committed, was directly in charge of, and was responsible to, the authority for the conduct of the business of the authority as well as the authority;

• shall be deemed to be guilty of the offence and shall be liable to be proceeded against and punished accordingly.

Therefore, the correct answer is the cases in which offences are made by authorities.

The correct answer is Nominal.

Key Points

 Nominal scale:

• It is also termed a classificatory scale.
• A variable measured on a nominal scale may have one, two or more subcategories depending upon the extent of variation.
• Example: Gender can be classified into two subcategories, such as male and female.

Therefore, the correct answer is Nominal.

Additional Information

 Ordinal scale:

• It usually ranks the subgroups in a certain sequence or order.
• Example: Examination marks can be measured either quantitatively, i.e., in absolute terms or percentage terms or qualitatively using subcategories, like above average, average and below average.
• The distance between these subcategories may or may not be equal.
• The socio-economic status can be categorized as lower class, middle class and higher class.
• The attitudinal or Likert scale also falls in the same category.

 Interval scale:

• An interval scale has all the characteristics of an ordinal scale.
• In addition, it uses a unit of measurement with arbitrary starting and terminating points.
• Example: Celsius scale is from 0°C to 100°C.

 Ratio scale:

• They are used to gather quantitative information.
• It combines the properties of nominal, ordinal and interval scales.
• In addition, it has its property.
• It has a fixed starting point.
• The ratio scale consists of equidistant points and has a meaningful zero point.
• Example: Measurements of physical dimensions like weight, height, distance etc.

The correct answer is 45.5

Key Points Given:

Mean marks = 47

Total students = 200

The mean marks of the top 25% students = 72

The mean marks of the bottom 25% students = 25

 Step 1:

Calculate the marks obtained by all students:

200 × 47 = 9400

 Calculate the marks obtained by the top 25% students:

25% of 200 = 50

50 × 72 = 3600

Calculate the marks obtained by the bottom 25% students:

50 × 25 = 1250

Marks obtained by the rest 50% students:

9400 - (3600 + 1250) = 4550

 Step 2:

$Mean = {4550\over 100}$ = 45.5

 Therefore, mean = 45.5

The correct answer is Bowley’s Coefficient of Skewness.

Key PointsKarl Pearson’s Coefficient of Skewness:

• This is the most frequently used method for measuring skewness and is based on the first absolute measure.
• Where the relationship between mean and mode is established,
• Absolute skewness = Mean - Mode
• Coefficient of skewness = (Mean - Mode) / Standard Deviation
• The coefficient of skewness generally lies within +1
• Where the relationship between mean and mode is not established,
• Absolute skewness = 3(Mean - Median)
• Coefficient of skewness = 3(Mean - Median) / Standard Deviation
• The coefficient of skewness generally lies within +3

Kelly’s Measure of Skewness:

• Kelley’s measure of skewness is given in terms of percentiles and deciles(D).
• The formula for measuring skewness is $J = {P_{90}+P_{10}-2P_{50}\over P_{90}-P_{10}}$

Bowley’s Coefficient of Skewness:

• It is based on the values of the median, lower and upper quartiles.
• This method suffers from the same limitations which are in the case of median and quartiles.
• Wherever the positional measures are given, skewness should be measured by Bowley's method.
• Absolute skewness = Q₃ + Q₁ - 2 Median
• Bowley's coefficient of skewness = (Q3 + Q1 - 2 Median) / (Q3 - Q1)
• The coefficient of skewness lies within the limit of ±1

Coefficient of Skewness based on moments:

• Coefficient of Skewness based on moments = $\mu_3^2\over\mu_2^3$

Therefore, the correct answer is Bowley’s Coefficient of Skewness.

Concept:

The probability density function is always positive, and it follows the below condition.

\(\mathop \smallint \limits_{ - \infty }^\infty f\left( x \right)dx = 1\)

Calculation:

\(f\left( x \right) = \left{ {\begin{array}{*{20}{c}} {k{x^3},;;0 \le x \le 1,}\ {0,;;otherwise;} \end{array}} \right.\)

\(\mathop \smallint \limits_0^1 k{x^3}dx = 1\)

$\Rightarrow \left[ {\frac{{k{x^4}}}{4}} \right]_0^1 = 1$

$\Rightarrow \frac{k}{4} = 1 \Rightarrow k = 4$

The correct answer is Discrete.

Key PointsVariables: 

• Variables are quantifiable traits that can be stated numerically in a variety of phrases and units.
• These are quantities that can be directly measured using quantitative techniques.
• For instance, height in inches, weight in kg, exam scores, etc.

Therefore, the correct answer is discrete.

The correct answer is a2 Var(x) + b2 Var(y) + 2ab Cov(x, y).

Key Points

• The variance of the linear combination of two random variables is a function of the variances as well as the covariance of those random variables.
• Consider,
• x and y are random variables, and
• a and b are real numbers.
• Then the variance of aX+bY is given by          
• Var(ax + by) = a² Var(x) + b² Var(y) + 2ab Cov(x,y).

Therefore, the correct answer is a2 Var(x) + b2 Var(y) + 2ab Cov(x, y).

The correct answer is Mosquitoes.

Key Points

• Invasive species frequently change the ecosystems where they are introduced, e.g., by affecting species interactions and population densities of native species.
• Due to globalization, increasing numbers of organisms are being transported around the globe.
• Seeds, eggs, dormant stages, parasites or pathogens can be unintentionally introduced as contaminants of intentionally introduced species.
• Climate change has already been shown and predicted to substantially alter biodiversity, causing changes in species distributions, species interactions and ecosystem processes.
• The Asian tiger mosquito (Aedes albopictus) is an unintentionally introduced species in many parts of the world, and climate change likely further increases its range.
• This invader also acts as a transmission vector for several human diseases (e.g., Dengue virus, West Nile virus).
• Invasive species often have broad climatic tolerances, which enables them to compete effectively with native species.
• Climate warming will favour exotic species from warmer regions and climates.
• Mosquitos are hence the most significant fingerprint of climate change concerning biotic invasion.

Therefore, the correct answer is mosquitoes.

The correct answer is Carbon dioxide.

Key Points

• Carbon dioxide (CO₂) is the primary greenhouse gas emitted through human activities.
• In 2020, CO₂ accounted for about 79% of all U.S. greenhouse gas emissions from human activities.
• Carbon dioxide is naturally present in the atmosphere as part of the Earth's carbon cycle (the natural circulation of carbon among the atmosphere, oceans, soil, plants, and animals).
• Human activities are altering the carbon cycle–both by adding more CO₂ to the atmosphere and by influencing the ability of natural sinks, like forests and soils, to remove and store CO₂ from the atmosphere.
• While CO₂ emissions come from a variety of natural sources, human-related emissions are responsible for the increase that has occurred in the atmosphere since the industrial revolution.
• Carbon dioxide is constantly being exchanged among the atmosphere, ocean, and land surface as it is both produced and absorbed by many microorganisms, plants, and animals.
• Emissions and removal of CO₂ by these natural processes, however, tend to balance, absent anthropogenic impacts.
• Since the Industrial Revolution began around 1750, human activities have contributed substantially to climate change by adding CO₂ and other heat-trapping gases to the atmosphere.

Therefore, the correct answer is carbon dioxide.

The correct answer is Smt. Gaura Devi.

Key Points

• The Chipko movement started in Reni village in the Chamoli district of the Garhwal region, Uttarakhand, in the year 1973 for the preservation of forests that were a source of livelihood for traditional communities.
• The name ‘Chipko’ comes from the word ‘embrace’, as the villagers hugged the trees and prevented them from being cut down.
• The Chipko Andolan is a movement that practised the methods of Satyagraha where both male and female activists from Uttarakhand played vital roles, including Gaura Devi, Sudesha Devi, Bachni Devi and Chandi Prasad Bhatt.

Therefore, the correct answer is Smt. Gaura Devi.

The correct answer is DN' = (${{DN-60} \over 158-60}$) * 255.

Key Points

• Linear contrast stretch translates the image pixel values from the observed range (D_min to D_max), scaling D_min to 0 and D_max to 255.
• Intermediate values retain their relative positions.

The expression that represents the transformed brightness level of a pixel is given as:

$DN' = ({DN - Min \over Max - Min})\times 255$

Here, Min = 60 and Max = 158

Therefore, the expression will be:

$DN' = ({DN - 60 \over 158 - 60})\times 255$

Therefore, the correct answer is  DN' = (${{DN-60} \over 158-60}$) * 255.

The correct answer is (a), (b), (c) and (d).

Key Points

• Water vapour is the most abundant greenhouse gas in the atmosphere, both by weight and volume.
• It is also an effective greenhouse gas, as it does absorb longwave radiation and radiates it back to the surface, thus contributing to warming.
• When compared to other greenhouse gases, water vapour stays in the atmosphere for a much shorter time.
• The increase in water vapour in the atmosphere thus contributes to even more warming i.e., it enhances the greenhouse effect.
• It plays a key role in climate feedback because of its heat-trapping ability.
• Warmer air holds more moisture than cooler air.
• Therefore, as greenhouse gas concentrations increase and global temperatures rise, the total amount of water vapour in the atmosphere also increases, further amplifying the warming effect.
• It is a radiatively active gas with absorption wavelengths of less than 8 μm and greater than 18 μm.
• 0.94 µm, 1.14 µm, 1.40 µm and 1.88 µm all fall under less than 8 μm wavelength.

Therefore, the correct answer is (a), (b), (c) and (d).

The correct answer is (a) only.

Key Points

Consider the third sentence of the third paragraph: Because the lighter isotope, 16O, evaporates more readily from the oceans, precipitation (and hence the glacial ice that it may form) is enriched in 16O.

• It can be seen that it is the lighter isotope of the oxygen molecule 16O that evaporates readily from the oceans and is transported to the polar regions where it drops in the form of precipitation and is found in abundance than 18O in the glacial ice.

Therefore, the correct answer is (a) only.

The correct answer is (b) only.

Key Points

Consider the first sentence of the fourth paragraph: Thus during periods when glaciers are extensive the concentration of 18O in seawater increases; conversely, during warmer interglacial periods when the amount of glacial ice drops dramatically, the amount of 18O relative to 16O in ocean water also drops.

• It can be seen that the amount of 18O is less than the amount of 16O in ocean water.
• Thus, \({^{18}O \over ^{16}O}\) is less than 1 in the ocean.
• Hence, the first statement is incorrect.

Consider the third sentence in the third paragraph: Of course, this leaves a greater concentration of the heavier isotope, 18O, in the ocean water.

• It can be seen that the amount of 18O is less than the amount of 16O in glacial ice.
• Thus, \({^{18}O \over ^{16}O}\) is less than 1 in the glacial ice.
• Hence, the second statement is correct.

Therefore, the correct answer is (b) only. ​

The correct answer is Higher \({^{18}O \over ^{16}O}\) in the glacial ice as compared to that in cold periods.

Key PointsConsider the first sentence in the fourth paragraph: Thus during periods when glaciers are extensive the concentration of 18O in seawater increases; conversely, during warmer interglacial periods when the amount of glacial ice drops dramatically, the amount of 18O relative to 16O in ocean water also drops.

It can be concluded that during the warmer interglacial periods, the amount of 18O drops in the ocean water and more 18O is evaporated from the oceans and transported to the glacial ice where its concentration increases during these warmer periods.

Therefore, the correct answer is higher \({^{18}O \over ^{16}O}\) in the glacial ice as compared to that in cold periods.

The correct answer is (a), (b) and (c).

Key Points

• Consider the first sentence of the second paragraph: We would expect that in any area of the ocean/atmosphere interface, the average annual temperature of the surface water of the ocean would approximate that of the contiguous atmosphere.

Thus the first sentence is correct.

• Consider the third sentence of the fourth paragraph: Consequently, periods of glacial activity can be determined from variations in the oxygen isotope ratio found in shells of certain microorganisms buried in deep-sea sediments.

Thus the second statement is correct.

• Consider the first sentence of the fourth paragraph: Thus during periods when glaciers are extensive the concentration of 18O in seawater increases; conversely, during warmer interglacial periods when the amount of glacial ice drops dramatically, the amount of 18O relative to 16O in ocean water also drops.

Thus the third statement is correct.

Therefore, the correct answer is (a), (b) and (c).

The correct answer is Wind velocity.

Key Points

• The Beaufort scale is used to describe the force of the wind.
• It was invented by Admiral Beaufort in 1805.
• The Beaufort wind scale is divided into a series of values, from zero for calm winds, up to twelve and above for hurricanes.
• Each value represents a specific range and classification of wind velocity with accompanying descriptions of the effects on surface features.

Therefore, the correct answer is wind velocity.

Additional Information

The correct answer is Nitrate radicals.

Key Points

• The chemistry of the night-time atmosphere is dominated by the nitrate radical (NO₃).
• These nitrate radicals are formed from the reaction of ozone (O₃) with nitrogen dioxide (NO₂).
• The reaction of NO₃ with NO₂ is the only way to form dinitrogen pentoxide (N₂O₅) in the atmosphere.
• This N₂O₅ acts as a store of NO₃.
• It can either decompose back to NO₃ and NO₂ or react with water to form nitric acid (HNO₃).
• NO₃ reacts with organic molecules in the same way as OH does.
• It removes a hydrogen atom from alkanes to form an organic alkyl radical (R) which then reacts with O₂ in the air to form peroxy radicals (RO₂).
• The radical is broken down by sunlight when the sun rises.
• NO₃ adds also to the double bonds of unsaturated organic compounds and forms peroxy nitrates after the addition of O₂.
• The lifetime of NO₃ / N₂O₅ decreases drastically as concentrations of water vapour increase.
• As water vapour levels increase, more of the NO₃ is converted to nitric acid (HNO₃), in particular on liquid films on surfaces.

Therefore, the correct answer is Nitrate radicals.

The correct answer is N2 > CO > H2 > CH4.

Key Points

• Producer gas is a combustible gas manufactured by blowing a mixture of steam and air upwards through a bed of hot coke, or coal, such that the fuel is completely gasified.
• The gas obtained from coke consists mainly of a mixture of carbon monoxide and hydrogen with the nitrogen from the blast of air.
• When coal is used the gas will contain, in addition, tar and the gases liberated during the carbonization of the coal in the fuel bed.

Concentrations of different components in producer gas are:

• Nitrogen - 55%
• Carbon monoxide - 27%
• Hydrogen - 12%
• Carbon dioxide - 5%
• Methane - 0.5%

​It has a heating value of about 5,000 kJ/m³.

When coal is used as fuel the producer gas contains about 3% methane and 0.5% higher hydrocarbons.

Therefore, the correct answer is N2 > CO > H2 > CH4.

The correct answer is (a) and (b) only.

Key Points

• The Lotka–Volterra model is frequently used to describe the dynamics of ecological systems in which two species interact, one a predator and one its prey.
• The Lotka–Volterra model assumes that the prey consumption rate by a predator is directly proportional to the prey abundance.
• This means that predator feeding is limited only by the amount of prey in the environment.

Thus the third and fourth statements are incorrect.

• The populations change through time according to the pair of equations:
• ${dx\over dt} = α x - β xy$
• ${dy\over dt} = δ xy - γ y$
• ​Where,
• x is the number of prey,
• y is the number of some predators,
• $dy\over dt$ and $dx\over dt$ represent the instantaneous growth rates of the two populations,
• t represents time,
• α, β, γ, δ are positive real parameters describing the interaction of the two species.
• Lotka-Volterra (LV) systems are not stable, that is, exhibiting either cyclic oscillation or divergent extinction of one species.
• A linearization of the equations yields a solution similar to simple harmonic motion (sinusoidal oscillation) with the population of predators trailing that of prey by 90° (π/2)  in the cycle.

Therefore, the correct answer is (a) and (b) only.

The correct answer is the Western Ghats.

Key Points

• Biodiversity hotspots are the regions which are known for their high species richness and endemism.
• Criteria to be classified as a biodiversity hotspot:
• The region should have at least 1500 species of vascular plants i.e., it should have a high degree of endemism.
• It must contain 30% (or less) of its original habitat, i.e. it must be threatened.
• There are 36 biodiversity hotspots in the world.
• India is known for its rich biodiversity and has around 24.46% of its geographical area covered by forests and trees.
• There are 4 biodiversity hotspots in India:
• The Himalayas,
• The Western Ghats,
• The Indo-Burma region, and
• The Sundaland

Therefore, the correct answer is the Western Ghats.

The correct answer is Water.

Key Points

• Water has an interesting property in that the amount of reflection depends greatly on the state (liquid or frozen) and the angle at which the radiation is striking it.
• Liquid water has a higher albedo when the sun angle is low.
• For example, just after the sun rises the sun's angle will be low and much of the radiation will be reflected by the water.
• This has important implications in locations the sun angle is low such as in high latitudes.
• High-latitude locations where the sun is near the horizon will reflect more solar radiation away than at low-latitude locations.
• Ice is a good reflector of solar radiation especially if it is a fresh snowfall.
• The albedo decreases as the age of the snow increases.
• The albedo of water at various states and sun angles:
• fresh snow - 80%
• sun near the horizon on the water - 65%
• old or dirty ice - 40%
• water with a sun angle of 30 degrees or more above the horizon - 8%

Therefore, the correct answer is water.

The correct answer is: Littoral zone, Limnetic zone, Profundal zone, Benthic zone.

Lentic ecosystems are standing water bodies such as lakes and ponds. Stratification in these ecosystems refers to the layering of water into different zones based on certain physical and biological characteristics. Understanding the correct order of these zones is essential for studying the ecological interactions and biodiversity within lentic ecosystems.

Key Points

• Littoral Zone:
• This is the topmost layer near the shore. It is well-lit by sunlight and supports a variety of aquatic plants and animals. The abundance of light allows for photosynthesis, making it one of the most productive zones.
• Limnetic Zone:
• The open surface water layer away from the shore, extending down to the depth that sunlight can penetrate. It supports plankton, fish, and other aquatic life forms that thrive in well-lit conditions.
• Profundal Zone:
• This deep-water zone below the limnetic zone lacks sufficient light for photosynthesis. It is inhabited by organisms adapted to cold, dark conditions, and low oxygen levels.
• Benthic Zone:
• The bottommost layer, including the sediment surface and sub-surface layers. It is rich in organic detritus and nutrients and populated by benthic organisms like decomposers, detritivores, and some bottom-dwelling fish.

Additional Information

• Thermal Stratification:
• Lentic ecosystems may also undergo thermal stratification, especially in summer, forming layers like the epilimnion, metalimnion (thermocline), and hypolimnion based on temperature gradients.
• Seasonal Changes:
• Seasonal changes such as turnover events in spring and autumn can mix the water layers, redistributing nutrients and oxygen throughout the ecosystem.
• Importance of Stratification:
• The stratification affects the distribution and abundance of organisms, nutrient cycling, and overall ecological dynamics within the lentic system.

The correct answer is Oxygen > Silicon > Aluminium > Iron.

Key Points Abundance of the elements in the Earth’s crust:

Therefore, the correct answer is Oxygen > Silicon > Aluminium > Iron.

The correct answer is (a) - (iii), (b) - (ii), (c) - (iv), (d) - (i).

Key Points

Therefore, the correct answer is (a) - (iii), (b) - (ii), (c) - (iv), (d) - (i). 

Additional Information

The correct answer is (a) - (iii), (b) - (iv), (c) - (i), (d) - (ii).

Key Points

Therefore, the correct answer is (a) - (iii), (b) - (iv), (c) - (i), (d) - (ii).

The correct answer is (a) - (iii), (b) - (i), (c) - (iv), (d) - (ii).

Key Points

Therefore, the correct answer is (a) - (iii), (b) - (i), (c) - (iv), (d) - (ii).

Additional Information

• The Environment (Protection) Act of 1986 authorizes the central government to protect and improve environmental quality, control and reduce pollution from all sources, and prohibit or restrict the setting and /or operation of any industrial facility on environmental grounds
• The Forest Conservation Act's main goal is to protect natural forests while also serving the fundamental requirements of those who live in or near them.
• The Water (Prevention and Control of Pollution) Act was enacted in 1974 to provide for the prevention and control of water pollution, and for the maintaining or restoring of the wholesomeness of water in the country.
• The Air (Prevention and Control of Pollution) Act of 1981, or the Air Act, in short, was a law passed by the Parliament of India to prevent and control the harmful effects of air pollution in India.

The correct answer is (a) - (iii), (b) - (ii), (c) - (iv), (d) - (i).

Key Points

Therefore, the correct answer is (a) - (iii), (b) - (ii), (c) - (iv), (d) - (i).

Additional Information

• Every year on April 22, Earth Day marks the anniversary of the birth of the modern environmental movement in 1970.
• Earth Day is an annual event on April 22 to demonstrate support for environmental protection.
• In 1994, the United Nations General Assembly proclaimed 16 September the International Day for the Preservation of the Ozone Layer, commemorating the date of the signing, in 1987, of the Montreal Protocol on Substances that Deplete the Ozone Layer.
• The United Nations has proclaimed May 22 The International Day for Biological Diversity (IDB) to increase understanding and awareness of biodiversity issues.
• World Wetlands Day, celebrated annually on 2 February, aims to raise global awareness about the vital role of wetlands for people and the planet. This day also marks the date of the adoption of the Convention on Wetlands on 2 February 1971, in the Iranian city of Ramsar.

The correct answer is Both (A) and (R) are true but (R) is not the correct explanation of (A).

Key Points

• Isostasy is an equilibrium between the earth's crust and its upper mantle, which properties the crust should have for being in equilibrium.
• It is an important subject in gravimetry, as the high-frequency portion of the gravity field of the earth is due to the mass variation and structure of the crust, which includes the topographic and bathymetric masses.
• It represents the relationship between the crust and the upper mantle so that the earth's crust is in an equilibrium state.
• It is the mechanical stability between the earth's crust (upstanding parts such as plains, plateaus, mountains, etc,  and low-lying parts such as the ocean floor) and mantle on the rotating earth.

Thus the assertion is true.

• Isostasy maintains an equilibrium state between buoyancy force and gravitational force.
• Buoyancy force pulls the crust upward and gravitational force pushes the crust downward.
• Isostasy is simply based on Archimedes' principle - an immersed object experiences a buoyant force equal to the weight of the displaced fluid.
• In the theory of isostasy, a mass above sea level is supported below sea level, and there is thus a certain depth at which the total weight per unit area is equal all around the Earth; this is known as the depth of compensation.

Thus the reason is also true but it does not correctly explains the assertion.

Therefore, the correct answer is Both (A) and (R) are true but (R) is not the correct explanation of (A).

The correct answer is Both (A) and (R) are true but (R) is not the correct explanation of (A).

Key Points

• The area in the basin of the Pacific Ocean that hosts more than 40% of geothermal energy resources is called the ring of fire.
• It is a volcanic belt where a large number of earthquakes and volcanic eruptions have been witnessed.
• It is also called the Circum-Pacific Belt or Circum-Pacific Seismic Belt.
• It is so-called because it marks a track around the rim of the pacific ocean.
• Also, since more than 75% of the earth’s volcanoes and 90% of earthquakes are witnessed here, it is called the ring of fire.

Thus the assertion is true.

• Geothermal energy is heat that is generated within the earth.
• Magma heats nearby rocks and underground aquifers.
• Hot water can be released through geysers, hot springs, steam vents, underwater hydrothermal vents, and mud pots.
• These are all sources of geothermal energy.
• A hydrothermal or geothermal system consists of three key elements: a geothermal heat source, fluid (water or steam), and a reservoir (porous and permeable rock).
• The heat from the core is constantly radiating outward and warming rocks, water, gas, and other geological material.

Thus the reason is also true but it does not explain the assertion.

Therefore, the correct answer is Both (A) and (R) are true but (R) is not the correct explanation of (A).

The correct answer is that UV radiation only destroys ozone.

Key Points

• Examine the second sentence of the passage:
• ​It takes UV photons to form ozone from oxygen and UV photons to release the chlorine from CFCs to destroy ozone.
• Examine the third sentence of the passage:
• ​Ozone depletion causes ground-level UV radiation-an environmental hazard.
• When we examine these two sentences, it can be concluded that it is the UV radiation that acts as a catalyst in both the formation and destruction of ozone.  Also, we can see that when there is a depletion of the ozone layer in the stratosphere, it leads to an increase in the concentration of UV radiation at the ground level which is an environmental hazard. Lastly, we conclude that during the formation of ozone, UV radiation first dissociates the molecule of oxygen to liberate an oxygen radical which then combines with another oxygen molecule to form the ozone molecule.

Therefore, the correct answer is that UV radiation only destroys ozone.

The correct answer is UVA and UVB.

Key Points

• Analyze the twelfth sentence of the passage: At this level, UV-C is effectively eliminated.
• By analysing this sentence and the passage as a whole, we conclude that the part of the UV radiation which has a wavelength around 250 nm and 200 nm are effectively absorbed by the ozone at the height of 40 km and 20 km respectively because these wavelengths form the centre of absorption bands of ozone.
• Thus, at the surface of the earth, UV radiation is composed mostly of UV-A and UV-B radiations.

Therefore, the correct answer is UVA and UVB.

The correct answer is UVC region.

Key Points

• Take a look at the eighth sentence of the passage: 
• ​Outside the earth’s atmosphere, the total solar radiation flux density of 1367 Wm-2 is the sum total of visible and IR (1254 Wm-2), UV-A (85.7 Wm-2), UV-B (21.1 Wm-2) and UV-C (6.4 Wm-2).
• ​We can see that UV-C forms only 6.4 Wm-2 out of the total solar radiation flux density of 1367 Wm-2.

Therefore, the correct answer is the UV-C region.

The correct answer is 250 nm.

Key Points

• Consider the tenth sentence of the passage: 
• ​By an altitude of 40 Km, O3 absorption has already made a significant difference, reducing the flux most around 250 nm because that corresponds to the centre of the absorption band.
• ​The stratosphere ranges from almost 12 km to 50 km in altitude and an altitude of 40 km comes in the stratosphere.
• Analyzing this sentence, we can conclude that at 40 km altitude, the UV radiation is maximum at 250 nm.

Therefore, the correct answer is 250 nm.

The correct answer is 20 Km.

Key Points

• Consider the eleventh sentence of the passage:
• ​At 20 km, above the surface, photon flux is almost the same as the surface value, except for the residual peak at 200 nm.
• ​After analysing this sentence, we can conclude that it is at 20 km of altitude the photon flux is the same as that of surface value.

Therefore, the correct answer is 20 Km.

The correct answer is 20 km.

Key Points

• Most of the atmosphere is confined to a narrow shell around the planet, with the pressure and density of air decreasing rapidly with altitude and gradually merging into the emptiness of space.
• 50% of the mass of the atmosphere is within 5.5 km of sea level.
• 90% is within about 20 km of sea level.
• 99.9% is up to 32 km.
• This is because the troposphere which extends for about 8 - 16 km contains more than 80% of the mass of the atmosphere where all the water vapours, clouds and precipitation takes place.
• Also, the troposphere and stratosphere jointly comprise almost 99.9% of the mass of the atmosphere.

Therefore, the correct answer is 20 km.

The correct answer is Utilitarian.

Key Points

Stewardship:

• Environmental stewardship refers to the responsible use and protection of the natural environment through active participation in conservation efforts and sustainable practices by individuals, small groups, nonprofit organizations, federal agencies, and other collective networks.

​​Utilitarian:

• Utilitarian philosophy indicates that resources should be used for the greatest number for the longest time.
• In the utilitarian account, morality is viewed essentially to be meant for human beings.
• In its moral concern, utilitarianism thus does not have any place for nature.

​Ecocentric:

• Ecocentrism recognizes earth's interactive living and non-living systems rather than just the Earth's organisms (biocentrism) as central in importance.

Biocentric:

• The term biocentrism encompasses all environmental ethics that "extend the status of the moral object from human beings to all living things in nature".
• Biocentric ethics calls for a rethinking of the relationship between humans and nature.

Therefore, the correct answer is Utilitarian.

The correct answer is 2.0.

Key Points

• The ratio of the distance travelled by the analyte to the distance travelled by the solvent front on a chromatogram is known as the retardation or retention factor (R_f) value.
• R_f = Distance travelled by analyte / Distance travelled by solvent front.
• In chromatographic techniques, the mobility of analytes with mobile solvents is different from the mobility of analytes added to stationary phases (phases).
• This discrepancy is explained by the different affinities of analytes for stationary and mobile solvents.
• The longer an analyte remains in a stationary phase, the lower the R_f value it will have, and the opposite is also true.
• R_f values are the ratios of solute (analyte) migration distances to solvent fronts, they are always less than one.
• Because solutes must have some attractive qualities with stationary phases, the solvent front always travels more than the solute front.
• R_f values will always be between 0 and 1 because the denominator has a greater value.

Therefore, the correct answer is 2.0.

The correct answer is both ClNO3 + HCl → Cl2 + HNO3 and Cl + O3 → ClO + O2.

Key Points

• Stratospheric temperatures in the polar vortex may drop to below - 90°C, which is cold enough to form polar stratospheric clouds (PSCs) even though the air is very dry.
• The ice crystals that make up polar clouds play a key role in the Antarctic phenomenon by providing reaction surfaces that allow chemical species to stay together long enough to react with each other.
• Several reactions take place on the surfaces of polar stratospheric cloud particles that result in the formation of chlorine gas. For example,
• ClONO₂ + H₂O → HOCl + HNO₃
• ClONO₂ + H₂O →  HOCl + HNO₃
• ClONO₂ + HCl →  Cl₂ + HNO₃
• ​Once the sun rises in the Antarctic spring in September, the chlorine gas formed during the darkness of winter photolytically decomposes into atomic chlorine:
• Cl₂ + hv →  2 Cl
• which then destroys ozone by reinitiating the catalytic destruction process.
• (Cl + O₃ →  ClO + O₂₎ + (ClO + O →  Cl + O₂) = O + O₃ →  2 O₂

Therefore, the correct answer is both ClNO3 + HCl → Cl2 + HNO3 and Cl + O3 → ClO + O2.

The correct answer is (c) only.

Key PointsConsider the first statement: Chromium (III) chemical species is more toxic than Chromium (VI).

• Chromium occurs in the environment primarily in two valence states, trivalent chromium (Cr III) and hexavalent chromium (Cr VI).
• Exposure may occur from natural or industrial sources of chromium.
• Chromium III is much less toxic than chromium (VI).
• The respiratory tract is also the major target organ for chromium (III) toxicity, similar to chromium (VI).
• Chromium (III) is an essential element in humans.
• The body can detoxify some amount of chromium (VI) to chromium (III).

Thus, the first statement is incorrect. 

Consider the second statement: Dimethylmercury chemical species is more toxic than methylmercury ion.

• Dimethylmercury is readily absorbed through the skin. A severely toxic dose requires the absorption of less than 0.1mL.
• Dimethylmercury ((CH₃)₂Hg) is a flammable, colourless liquid, and one of the strongest known neurotoxins.
• Methylmercury (CH₃Hg) is the most toxic form.
• Methylmercury is the most toxic among the mercury species because of its volatility and its ability to pass through biological membranes such as the BBB and the placental barrier.
• The nervous system and kidneys are the two major target organs.

Thus, the second statement is incorrect.

Consider the third statement: Arsenic (III) is more toxic than Arsenic (V).

• Arsenic occurs in two oxidation states a trivalent form, arsenite (As2O3; As III) and a pentavalent form, arsenate (As2O5; As V).
• As (III) is 60 times more toxic than As (V).
• Organic arsenic is non-toxic whereas inorganic arsenic is toxic.

​Thus, the third statement is correct.

Therefore, the correct answer is (c) only.

The correct answer is (a), (b) and (c) only.

Key Points

• The atmosphere is the recipient of a vast array of chemical compounds emitted by natural processes and, in recent times, increasingly emitted by human activity.
• Most trace gases emitted into the atmosphere are removed by oxidizing chemical reactions involving ozone and the hydroxyl free radical.
• The rate of this self-cleansing process is often referred to as the oxidation capacity of the atmosphere.
• The oxidation of this wide variety of chemical compounds is a key process proceeding in our oxygen-rich atmosphere.
• The compounds undergoing oxidation include hydrocarbons (RH), carbon monoxide (CO), sulfur dioxide (SO₂), nitrogen oxides (NOx), ammonia (NH₃), hydrofluorocarbons, and hydrochlorofluorocarbons.
• The atmospheric oxidation process depends on the abundant presence of molecular oxygen.

Therefore, the correct answer is (a), (b) and (c) only.

The correct answer is (b) and (c) only.

Key Points

• The world’s forests cover 30% of the earth’s surface and serve as a source of diverse values to human society.
• Healthy forest ecosystems provide a wide range of services – including:

1. Reliable clean water
2. Climate regulation
3. Productive soils
4. Pollination by insects and birds
5. Biodiversity
6. Carbon
7. Watershed services
8. Soil conservation
9. Recreational and cultural values
10. Social and economic benefits for communities
11. High Conservation Values

Not only are forests home to more than 80% of all species living on land, but they are also crucial sources of food, medicine, drinking water, and immense recreational, aesthetic, and spiritual benefits for millions of people.

Therefore, the correct answer is (b) and (c) only**.**

Additional Information

Experts have identified four different kinds of services, all vital to human health and well-being:

• Provisioning services supply the goods themselves, such as food, water, timber and fibre.
• Regulating services govern climate and rainfall, water (e.g. flooding), waste, and the spread of disease.
• Cultural services cover the beauty, inspiration and recreation that contribute to our spiritual welfare.
• Supporting services include soil formation, photosynthesis and nutrient cycling, which underpin growth and production.

The correct answer is (b) only.

Key Points

• Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a zinc blended crystal structure.
• Gallium arsenide (GaAs) has a band gap of 1.42 eV, close to the value giving peak solar efficiency.
• Because of the presence of a direct band gap, it can be used to absorb and emit light efficiently contrary to silicon which has an indirect band gap and so is relatively poor at emitting light.
• It is characterised by more sharp absorption band and a large extinction coefficient.

Therefore, the correct answer is (b) only.

Additional Information

• The extinction coefficient refers to how strongly a species absorbs or reflects radiation at a particular wavelength.

The correct answer is 198 W.

Key Points Given:

• Area of photovoltaic cells = 1.5 m × 2.0 m
• Solar insolation = 550 W/m2
• Efficiency, η = 12%

 Using the formula:

 ${\eta} = {Power\ output \over Area \times Solar Insolation}\times100$

 ${12} = {Power\ output \over 1.5\times2.0 \times 550}\times100$

 ${P} = {12\times 1.5\times2.0\times550 \over100}$

 Therefore, P = 198 W

The correct answer is (a) and (c) only.

Key PointsConsider the first statement: Alum is added to water as a coagulating agent.

• In a water treatment system, coagulation is considered to be a chemical treatment process that destabilizes particles (makes them sticky).
• The coagulant's purpose is to neutralize the surface charge, thus allowing the particles to come together to form larger particles that can be more easily removed.
• The usual coagulant is alum, Al₂(SO₄)₃·18H₂O.
• Other coagulants like FeCl₃, FeSO₄ and polyelectrolyte can be used.
• Alum ionizes in water, producing Al³⁺ ions, some of which neutralize the negative charges on the colloids.

Thus, the first statement is correct.

Consider the second statement: Residual chlorine is considered a major disadvantage of using chlorination for the disinfection of water.

• The most commonly used method of disinfection is free chlorine disinfection because it is cheap, reliable and easy to use.
• Free chlorine is developed by dosing with either chlorine gas (Cl_2(g)), sodium hypochlorite (NaOCl) or calcium hypochlorite (Ca(OCl)₂).
• A principal advantage of chlorination over other forms of disinfection is that a chlorine residual is created that provides secondary disinfection of the treated water after leaving the treatment plant.
• This guards against possible contamination that might occur in the water distribution system.

Thus, the second statement is incorrect.

Consider the third statement: The addition of ammonia to water treated with chlorine leads to the formation of chloramines.

• To increase the lifetime of this residual, some systems add ammonia to the treated water.
• Ammonia reacts with free chlorine to form chloramines (NH₂Cl, NHCl₂ and NCl₃), which are termed combined chlorine.
• Chloramines are less effective as oxidants than HOCl and hence are seldom used as primary disinfectants.
• However, they are more persistent than free chlorine and maintain secondary disinfection in distribution systems even with long residence times.

Thus, the third statement is correct.

Therefore, the correct answer is (a) and (c) only.

Additional Information

The water treatment system consists of the following sequence of steps:

1. Screening and grit removal
2. Primary sedimentation
3. Rapid mixing and coagulation
4. Flocculation
5. Secondary settling
6. Filtration
7. Sludge processing
8. Disinfection contact

The correct answer is (a), (b) and (c).

 Key Points

• The X² test is one of the simplest and most widely used non-parametric tests in statistical work.
• The quantity X2 describes the magnitude of the discrepancy between theory and observation.

It is defined as:

​${\chi^2} = {\sum (O-E)^2\over E}$

Where,

O = Observed Frequency and E = Expected frequency 

• A chi-squared distribution constructed by squaring a single standard normal distribution is said to have 1 degree of freedom. mathematically designate $({{X-µ} \over σ})^2$
• X2 test enables us to ascertain how appropriately the theoretical distributions such as binomial, Poisson, normal etc., fit the empirical distribution.
• This implies X2 test is used as a test of goodness of fit.

Therefore, the correct answer is (a), (b), and (c).

The correct answer is Solution, Carbonation, Hydration, Hydrolysis, and Oxidation.

Key Points

• Chemical weathering occurs when the minerals in the rock undergo chemical alteration or dissolution.
• In these chemical reactions, some minerals dissolve while others combine with water and atmospheric components such as Rocks and minerals such as oxygen and carbon dioxide to form new minerals.
• Chemical weathering involves the following reactions: 
• Solution: It is a chemical weathering reaction in which carbonic acid dissolves minerals like calcite, found in limestones (a common sedimentary rock). Water is an exceptionally good solvent and dissolves many minerals. Limestone, dolomite, common salt, and gypsum are dissolved in water.
• Carbonation: It is a chemical union of a mineral with CO₂ to form carbonate. Carbonate reacts with water forming bicarbonate which is in a dissolved state. Granite is the most commonly occurring rock on Earth and is weathered in the same way. Its feldspar changes to kaolin.
• Hydration: This reaction involves the chemical union with water. For example, mineral anhydrite may be converted to gypsum.
• Hydrolysis: It affects the carbonate and silicate minerals. In such reactions, pure water ionizes slightly and reacts with silicate minerals.
• Oxidation: It involves the loss of an electron from a cation in a crystal. The reaction involves a chemical union with oxygen. Readily oxidised elements include iron, sulphur, and chromium.

Therefore, the correct answer is Solution, Carbonation, Hydration, Hydrolysis, and Oxidation.

The correct answer is (a) - (ii), (b) - (i), (c) - (iv), (d) - (iii).

Key Points

Therefore, the correct answer is (a) - (ii), (b) - (i), (c) - (iv), (d) - (iii).