UGC NET Paper 2: Environmental Science 21st Nov 2021 (Previous Year Paper)

The correct answer is Gomukh.

Key Points

• River Ganga
• It originates in the Himalaya Mountains at Gomukh, the terminus of the Gongotri Glacier. Here, it is known as the Bhagirathi.
• It cuts through the Central and the Lesser Himalayas in narrow gorges.
• At Devprayag, the Bhagirathi meets the Alaknanda; hereafter, it is known as the Ganga.
• The river has a length of 2,525 km.
• It is shared by Uttarakhand (110 km) and Uttar Pradesh (1,450 km), Bihar (445 km) and West Bengal (520 km).
• The river finally discharges itself into the Bay of Bengal near the Sagar Island.
• Left tributaries: Gomti, Ghaghara, Gandak, Burhi Gandak, Koshi, Mahananda, Ramganga, Garra.
• Right tributaries: Yamuna, Sone, Punpun, Damodar.

Explanation:

Theoretical Oxygen Demand:

It is a method of calculating the amount of oxygen required by various constituents of the organic matter present in wastewater. Therefore, D is correct.

Actual Oxygen Demand:

It depends on the biodegradability of the compound and the specific organism metabolizing the compound and is measured experimentally by Biological Oxygen Demand (BOD). BOD final is calculated after 5 days at the temperature of 20⁰C. Therefore, B is correct.

Reaeration and deoxygenation are important factors as it is of biological activity where the uptake of oxygen by microorganisms in performing the decomposition process. Therefore, A is not correct.

Hence, option 2 is the correct answer.

Additional Information 

Chemical Oxygen Demand: It is the amount of required oxygen to decompose both the organic and inorganic matter present in the wastewater.

Thus, ThOD > COD > Initial BOD > Final BOD.

Explanation

Properties of water: 

• Specific heat: It is the amount of heat energy that is required to increase the temperature of a unit mass of a substance by one degree. Water has a high specific heat and a lot of energy must be absorbed by it before its temperature changes. Therefore, A is correct.
• The heat of vaporization: It is the energy required to change a given quantity of a substance into a gas. The strength of hydrogen bonds between water molecules are strong, water has to be heated to 100 ℃ before it changes phase. The heat of vaporization for water is high at about 40.65 kJ/mol. Therefore, B is correct.
• Less dense solid phase: Water in its solid phase (ice) is less dense than its liquid phase. For instance, if we put ice into a glass of water, it doesn't sink but floats. This phenomenon is also related to the hydrogen bonds between water molecules.
• Bipolar nature: It is the presence of positive and negative charges in water where the molecule has a slightly positive charge on one side (where the hydrogen atoms are attached) and slightly negative on the other (just oxygen).
• Absorption of infrared radiation: Water can absorb infrared radiation (heat) from the sun. As a result of this, the oceans and other water bodies act as heat reservoirs and can help moderate the Earth's climate.
• Melting point (0℃) and Boiling point (100 ℃): This large difference between the melting and boiling point is very important because it means that water can exist as a liquid over a large range of temperatures.

Hence, option 3 is the correct answer.

Explanation

Scanning Electron Microscope(SEM):

• The Scanning electron microscope uses electrons instead of light to form an image.
• It is widely used in materials science for research, quality control, and failure analysis.
• It plays a major role in nanotubes, nanofibers, superconductors, and alloy strength investigation.

X-Ray Fluorescence:

• It is a non-destructive analytical technique used to determine the elemental composition of materials.
• A primary X-ray initially generated in an X-ray tube hits an inner shell electron of the atom and ejects the electron from the atom.
• The open position is filled by an electron from a further outer shell and fluorescence radiation is emitted.

Transmission electron microscope:

• This microscope uses a particle beam of electrons to visualize specimens and generate a highly-magnified image.
• It magnifies objects up to 2 million times.
• This technique is widely used to observe the features of very small specimens.
• It uses an accelerated beam of electrons, which passes through a very thin specimen to observe the features including structure and morphology.

X-Ray Diffraction:

• It is an experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure allows the beam of incident X-rays to diffract into many specific directions.
• It is used to obtain a three-dimensional molecular structure from a crystal.
• A purified sample at high concentration is crystallized and the crystals are exposed to an x-ray beam.

​Hence, Transmission Electron Microscopy & X‐Ray Diffraction are used to determine the crystal structure of a compound/material. So, option 4 is the correct answer.

Explanation

Living fossil

• An organism that remained essentially unchanged from earlier geologic times and whose close relatives are usually extinct.

Example:

• Ginkgo biloba also called the maidenhair tree, which is the only remaining representative of the Ginkgoaceae family.
• Latimeria is a rare genus of fish that includes two extant species- Latimeria chalumnae and Latimeria menadoensis.

Hence, option 1 is the correct answer.

Explanation:

Perihelion:

• It is the phenomenon where the earth is closest to the sun.
• This occurs about two weeks after the December solstice.

Aphelion:

• It is the phenomenon where the earth is farthest from the sun.
• This occurs two weeks after the June solstice.

The earth’s spin axis is titled with respect to its orbital plane which causes seasons.

Hence, option 2 is the correct answer.

Explanation:

Ferromagnesian minerals:

• These are silicate minerals.
• These minerals contain a higher proportion of iron and magnesium. These minerals are dark in color.
• They tend to look metallic in their lustre.
• They have relatively high density. They also have magnetic properties.

Hence, option 3 is the correct answer.

Explanation:

Clay minerals in soil:

• There are four major types of colloids present in the soil.
• Layer silicate clays
• Iron and aluminum oxide clays (sesquioxide clays)
• Allophane and associated amorphous clays
• Humus.
• Layer silicate clays, iron and aluminum oxide clays, allophane, and associated amorphous clays are inorganic colloids while humus is an organic colloid.
• Some clay particles are technically not colloids yet they have colloid-like properties
• The humus is often referred to as an organic colloid and consists of various chains and loops of linked carbon atoms.
• The humus colloids are not crystalline.
• They are composed basically of carbon, hydrogen, and oxygen rather than of silicon, aluminum, iron, oxygen, and hydroxyl groups.

The correct answer is A and B only.

Key Points

• Ritcher Scale: It is used to determine the magnitude of an earthquake**.**
• It is an open-ended logarithmic scale** i.e, **the logarithm of the amplitude of the largest seismic wave is recorded by a seismograph.
• The vibration in an earthquake with a magnitude of 7 is 10 times greater in magnitude than that of an earthquake with a magnitude of 6 considering it is a base-10 logarithm scale.
• The order of velocity of seismic waves is:

           P-waves > S-waves > R-waves > L-waves

Therefore, only statements A and B are correct. 

Additional Information

Earthquake waves (seismic waves) are basically of two types: 1. Body waves 2. Surface waves

• Body waves are of two types: Primary or P - waves and Secondary or S - waves.
• Surface waves are of two types: Rayleigh or R - waves and Love or L - waves.

The correct answer is (A) and (B) Only.

 Key Points

• The regression coefficient is a statistical measure that represents the average functional relationship between two or more variables.
• In regression analysis, one variable is regarded as dependent, while the other is regarded as independent.
• As a result, it assesses the degree to which one variable is dependent on another.
• The geometric mean of the two regression coefficients equals the correlation coefficient.
• Properties of the regression line and correlation coefficient:
• ​If the correlation coefficient r_xy = 0, then the two lines of regression are perpendicular to each other.
• ​If the correlation coefficient rxy = +1, then the two lines of regression are parallel to each other.
• If one regression coefficient is greater than unity, then the other regression coefficient must be lesser than unity.

Therefore, statement C is incorrect.

Concept-

Toxic elements-

• Organisms require some of the trace elements as essential micronutrients, including copper, iron, molybdenum, zinc, and in some cases aluminum, nickel, and selenium. Under certain conditions, however, these same elements can accumulate to high concentrations in organisms and cause ecological damage.
• Trace elements that are most often associated with environmental toxicity are the heavy metals cadmium, chromium, cobalt, copper, iron, lead, mercury, nickel, silver, tin, and zinc, as well as the lighter elements aluminum, arsenic, and selenium.
• Human activities have caused additional examples of pollution by toxic elements, particularly in the vicinity of industrial sources such as smelters.
• In addition, emissions of mercury and lead from power plants and automobiles have caused widespread contamination of remote environments, although it is not yet certain that this is causing ecological damage.

Wood preservative-

• Wood preservative products are those that control wood degradation problems due to fungal rot or decay, sapstain, molds, or wood-destroying insects.
• Wood preservatives containing chromated arsenicals include preservatives containing chromium, copper, and arsenic.

Food cans - It contains lead.

Colored printing inks - It contains cadmium.

Fluorescent lamps - It contains mercury.

So the correct option is option 2.

The correct answer is (A) ‐ (iii), (B) ‐ (iv), (C) ‐ (ii), (D) ‐ (i)

Confusion PointsAn incorrect pair has been given in the PYP as Musk deer and Bison both are in the Schedule I. We have replaced Bison with House Rat to provide correct matching of the pairs. 

• Musk Deer - Schedule-I
• Himalayan Black Bear - Schedule II
• Pitcher Plant - Schedule VI
• Bison (Gaur) - Schedule-I
• House rat - Schedule IV

Key Points 

Additional Information

• Wildlife (Protection) Act, 1972: The Act was enacted for the protection of plants and animal species. 
• It extends to the whole of India except the State of Jammu and Kashmir.
• The Central Government appoints the Director of Wildlife Preservation.
• The State Governments appoint a Chief Wildlife Warden (CWLW) who heads the Wildlife Wing of the department and exercises complete administrative control over Protected Areas (PAs) within a state.
• Bodies Constituted under the Act:
• National Board for Wildlife
• State Board for Wildlife
• Central Zoo Authority
• National Tiger Conservation Authority
• Wildlife Crime Control Bureau

Explanation:

The correct answer is Soils containing a balanced community of living organisms.

Key Points

• Entropy is a term central to the field of thermodynamics. It is a thermodynamic property that measures the degree of disorder or randomness. Hence, entropy can serve as a dynamic crucial concept to characterize the organization of the unique thermodynamic states of life and earth's habitable environments.
• The second law states "For isolated systems that do not exchange energy or mass with their surroundings, the entropy of that system increases".
• Soils that contain a balanced community of living organisms are in a constant exchange of energy through the processes like nutrient cycling, homeostasis, energy conversions, decomposition, etc. Therefore, this system has the lowest entropy.

Therefore, soils containing a balanced community of living organisms have the lowest entropy.

The correct answer is Dimethyl mercury.

Key Points

• Elemental mercury is inert, stable, and insoluble in water but it dissolves in lipids.
• Monomethyl mercury is soluble in most organic solvents but insoluble in water (inorganic solvent).
• The solubility of mercury vapour in water has been measured by means of atomic absorption spectrophotometry over the temperature range of 5 - 60°C under atmospheric pressure. The aqueous solubility obeys Henry's law at each temperature.
• The heat of the solution of mercury vapour is found to be -5.3 KCal/mol.
• Dimethylmercury is capable of permeating many materials, including plastic and rubber compounds.

The water solubilities of different compounds of mercury are:

• Hg (mercury) water solubility is 0.000056 g/L
• CH₃HgCl (methyl mercury chloride) water solubility is 0.1 g/L
• (CH3)₂Hg (dimethyl mercury) water solubility is 1 g/L

​Therefore, Dimethyl mercury is completely soluble in water.

Explanation:

Given:

Power produced = 5000 MWh

The heat produced (in the form of energy) = 30,000 GJ

Input energy = 60,000 GJ

To get the given values in the same units, we have to convert 5000 MWh in MJ

That is,  $\frac{Heat \ Input}{kW\ hr\ electricity}$ = $5000 MW hr\ \times \frac{1 Mj/sec}{1\ Mw}\ \times 3600\ sec/hr$

= 18000000 MJ

1 MJ = 0.001 GJ

Therefore, Total input energy = 18000 GJ + 30,000 GJ = 48000 GJ

We know, $Efficiency = {Output\ Energy{} \over Input\ Energy}$

Therefore,   $Efficiency = {48000{} \over 60000}$ x 100 = 80%

Concept:

Ozone depletion Potential (ODP):

• It is a measure of a chemical compound that is the relative amount of degradation to the ozone layer it can cause with trichlorofluoromethane (CFC-11) being fixed at an ODP of 1.0.
• ODP can be estimated from the molecular structure of a given substance.

Ozone-depleting substances include:

• Chlorofluorocarbons (CFCs)
• Hydrobromofluorocarbons (HBFCs)
• Halons
• Methyl Bromide- ODP
• Carbon tetrachloride
• Methyl Chloroform
• Hydrochlorofluorocarbons(HCFCs)- least ODP ranging from 0.01-0.1. Hence,  option 3 is the correct answer.

Ammonia and Carbon dioxide do not cause depletion of Ozone, so they have zero ODP.

Concept:

• Processes of weathering produce sediment. Particles continue to be broken down as they are transported and sorted (By the processes of erosion).
• Following deposition, sediments become sedimentary rocks through the processes of lithification.

There are two types of sedimentary rocks.

1) Detrital sedimentary rocks:  Rocks that are formed from transported solid material. 

Detritus - Latin for "worn down." 

Types of detrital sedimentary rocks:

• Conglomerate - Forms from cemented GRAVEL (a mixture of cobbles, pebbles, and coarse sand), such as from a stream gravel bar. The gravel particles are "rounded" by erosion processes.
• Breccia- Forms from cemented "gravel-sized" fragments of rock, but the rock fragments are very "angular" in shape. Broken rock fragments are common in fault zones and in volcanic areas.
• Sandstone - A sedimentary rock formed by cemented SAND. (Sand particles are between 1/16-2mm; sandstone usually displays a high degree of sorting due to wind and water transport processes
• SIltstone- Forms from silt (particle sizes: 1/16-1/256mm).
• Shale - Forms from clay(particles: <1/256mm); shale displays laminae (layering).

2) Chemical sedimentary rocks:

• Formed when dissolved substances precipitate from water to form sediments and eventually rock; include salts such as rock salt, Gypsum, and Limestone, and biochemically mediated rocks such as peat, and reef rock (organic limestone).

So chalk is not an example of detritus sedimentary rocks.

Explanation:

• Soil particles are classified to determine the texture of the soil and grouped with similar attributes. The size of the particle majorly influences the water-holding capacity and the porosity of the soil.
• Majorly two classification systems viz. International Union/Society of Soil Sciences (ISSS/IUSS) and United Nations Department of Agriculture (USDA) are as follows,

Hence, Option 3 is the correct answer.**

Concept-

• A coefficient describing the relative ease with which groundwater can move through a permeable layer of rock or soil.
• Soils are generally divided on the basis of their particle size into coarse-grained and fine-grained soils.
• Coarse-grained soils are of particle size greater than 0.075 mm or 75 microns and particles smaller than this make up fine-grained soils.
• Further coarse grains are divided into gravel and sand, and fine grains are divided into silt and clay sized.

• Gravel-sized particles are larger than 4.75mm and sand particles are between 4.75mm to 75 microns.
• Silt-sized particles are of size 75 microns to 2 microns, and clay-sized particles are of size less than 2 microns.
• The order of hydraulic conductivity will be Gravel > Sandstone > sand > Clay.

Explanation

Shifting Cultivation

• It is a form of agriculture where the farmers cultivate the land for two or three seasons temporarily and shifts to another area.
• In this farming, the forest land is cleared by burning and is allowed for the cultivation of crops. This burnt biomass increases the soil nutrients. Therefore, this system of cultivation is called slash-and-burn farming.
• This farming is also known as primitive subsistence farming.

Different names for shifting cultivation

• Jhuming/Bewar – Northeastern states of India
• Podu- Andhra Pradesh
• Ladang – Malaysia, Indonesia
• Milpa – Mexico
• Roca – Brazil
• Ray- Vietnam

Hence option 4 is the correct answer.

Explanation:

Dominant species

• These are species that have a relatively high abundance to other species in a community and ultimately have proportionate effects on the functions of the ecosystem.
• Example: Conifers are the dominant species in the temperate forest.

Keystone species

• These species have a greater impact on the population of a particular ecosystem and maintain biodiversity and play a critical role in the food web.
• Without these species, an entire ecosystem would radically change or cease to exist altogether.
• Example: Bees as pollinator supports the reproduction of flowering plants in higher proportion.

Hence, option 2 is the correct answer.

Indicator species

• These species reflect the environmental condition by their presence, absence, or in abundance.
• They are the signals to diagnose the health condition of a particular ecosystem.
• Example: Mosses often indicate acid soil.

Flagship species

• These species are the icon that needs to be conserved in a social context. Thus, inducing people to support the conservation of these species.
• Example: The Bengal Tiger is a flagship species by World Wildlife Fund.

The correct answer is Musk Deer.

Key Points

• Kedarnath Wildlife Sanctuary 
• It is situated in Chamoli, Uttrakhand.
• It is the largest protected area in the region of the Western Himalayas.
• It is best known for the endangered musk deer and is thus called the Kedarnath Musk Deer Sanctuary.
• The sanctuary takes its name from the famous Hindu temple of Kedarnath which is just outside its northern border.
• The sanctuary is rich in fauna and one can find animals like snow leopards, Indian leopards, jackals, Himalayan black bears, yellow-throated martens, red fox, etc.
• Some of the popular avifauna are snow partridge, Himalayan monal, Koklass pheasant, little-pied flycatcher, grey-cheeked warbler, West Himalayan bush warbler, etc.
• The management of the wildlife sanctuary is done by the Uttarakhand Forest department.
• The Divisional Forest Officer(DFO) Kedarnath Wildlife Division is responsible for scientific management of the wildlife sanctuary as per the approved management plan.

Concept:

• BOD represents the amount of biodegradable organic matter present in water.
• It also indicates the amount of treatment for purifying. If the BOD is high the extent of treatment required will be high.
• The permissible limit declared by CPCB for various parameters is given below so that treated wastewater can be discharged into the garden for watering-

Explanation

• The mass units used to measure the air pollutants include milligrams (one-thousandth of a gram), micrograms (one-millionth of a gram), nanograms, and pictograms calculated per volume of air (cubic meters or cubic feet).
• However, these concentrations can also be expressed as parts per million (ppm) or parts per billion (ppb) by volume. This can be done based on the molecular weight of the chemical.

The formula for conversion between µg/m3 (micrograms per cubic meter) and ppb (parts per billion) is as follows:

Converting from ppb to µg/m3 is:

Concentration (µg/m3) = molecular weight x concentration (ppb) / 24.45 ………..… (I)

Calculations:

• STP refers to the standard temperature at 25°C and the pressure is at 1 atmosphere (1 atm = 1.01325 bar).
• The number 24.45 in the equation is the volume (liters) of a mole (gram molecular weight) of a gas at STP.

Molecular weight of Sulphur dioxide (SO₂) = 32.065 (S) + 2(15.999) O2 = 64.06 g/mol

Now, substituting the above values in equation (I) give,

Concentration (µg/m3) = $\frac{64.06 \ \times\ 1}{24.45}$ = 2.62 µg/m³.

The nearest value is in Option 4. Hence, it is the correct answer.

The correct answer is Chironomus.

Key Points

• The Chironomidae are very important constituents of the benthic macro-invertebrate community at the stations downstream of the effluent.
• Out of all the microbes enlisted, Chironomus riparius is the most tolerant species.
• They contain the red blood pigment 'haemoglobin', which allows them to absorb oxygen from the water more readily.
• As a result, they can survive in habitats with very low levels of oxygen, including heavily polluted areas.

Therefore, the most tolerant organism to sewage pollution is Chironomus.

Explanation

illuviation:

• It is the process of deposition of illuvium. illuvium is the material that got removed from one horizon (a process called eluviation) of the soil to another.
• It includes organic matter, silicate clay, and hydrous oxides of iron and aluminum.
• This removal is usually by the action of rainwater.
• This transport of material may be either mechanical or chemical.
• This accumulation of these materials occurs in the subsoil horizon or B horizon. This zone is also known as zones of illuviation.

Hence, option 4 is the correct answer.

Concept:

• Blood is a connective tissue, that has an iron-containing pigment called Haemoglobin.
• Haemoglobin gives a red colour to the blood and is responsible for the transport of O₂molecules throughout the body.
• When haemoglobin combines with oxygen from the lungs it forms oxyhaemoglobin.
• Oxyhaemoglobin transports oxygen to the cells of the body.
• Oxygen gets attached to Haemoglobin because it shows an affinity towards it, but other gases such as Carbon monoxide (CO), Carbon dioxide (CO2) also show an affinity towards it.

Explanation:

• When the outside environment is rich in CO, and it is being inhaled, it starts to displace oxygen bind on Haemoglobin.
• The displacement occurs because CO shows several hundred times stronger affinities towards haemoglobin than oxygen, and it forms carboxyhaemoglobin.
• Carbon monoxide is harmful to human beings, as it has a high affinity with haemoglobin as compared to oxygen.
• This leads to the scarcity of oxygen in the body, and sufficient oxygen is not available for organs.
• Concentrations as low as 20 or 30 PPM can be harmful if exposed for several hours.

Solution:

Ascending order is 4, 5, 5, 6, 6, 6, 7, 7, 8, 9

and all the failed students have marks less than 4.

data in ascending order is x, y, z, 4, 5, 5, 6, 6, 6, 7, 7, 8, 9

number of observations is 13

Median is middle-term i.e., 7

Hence, the median is 6.

The correct answer is ∼0.84.

Key Points

• Normal distribution or continuous probability distribution presents a bell-shaped symmetrical curve called a normal distribution curve.
• In the normal curve, all distribution is bilaterally symmetrical about the mean.

For every normal curve,

1. 68.26% of data points fall within 1 standard deviation of mean.
2. 95.44% of data points fall within 2 standard deviations of mean.
3. 99.73% of data points fall within 3 standard deviations of mean.​

          Fig. Area under Standard Normal Curve

Distance from mean ordinate

• μ to +1σ = 34.13% = 0.3413
• μ to -1σ = 34.13% = 0.3413
• -1σ to -2σ = 13.59% = 0.1359
• -2σ to -3σ = 2.14% = 0.0214
• -3σ to -∞ = 0.14% = 0.0014

          ​=> 0.3413+0.3413+0.1359+0.0214+0.0014 = 0.8413 = ∼0.84

Where μ = Mean

​Therefore, the correct answer is ∼0.84.

Additional Information

Concept:

 Let the exponential growth equation of population can be modeled as

N = ${N_0}{e^{ - λ t}}$ 

Where N = Population at any time t

λ = Growth rate constant, t = time

Calculation:

The population of the city doubled in a span of 20 years

N = 2N₀, t = 20 yrs

2N₀ = N₀e^-λt 

λ  = $\frac{0.693}{20}$ = - 3.5 %

Explanation

Bayes’ theorem

• It states that the conditional probability of an event, based on the occurrence of another event, is equal to the likelihood of the second event given the first event multiplied by the probability of the first event.

Central Limit theorem

• It explains that the sampling distribution of the mean will always be normally distributed, as long as the sample size is large enough.

Chebyshev’s theorem

• This estimates the minimum proportion of observations that fall within a specified number of standard deviations from the mean.

Gauss- Markov theorem

• It states that when the linear regression model satisfies the first six classical assumptions, then ordinary least squares OLS regression produces unbiased estimates that have the smallest variance of all possible linear estimators.

​Hence, option 4 is the correct answer.

Concept-

Walkley and Black method

• The determination of soil organic carbon is based on the Walkley & Black chromic acid wet oxidation method.
• Oxidizable organic carbon in the soil is oxidized by 0.167 M potassium dichromate (K₂Cr₂O₇) solution in concentrated sulfuric acid.
• The heat of the reaction raises the temperature which is sufficient to induce substantial oxidation.
• Organic carbon estimated by this method excludes most of the less active organic matter.
• Recoveries of the total Soil Organic Carbon by this method can typically be between 75 – 90 % in surface soils and will vary with soil type and depth.
• Walkley & Black found that on average about 77% of the organic C was recovered by the heat of the dilution procedure, and they proposed that a correction factor of 1.3 be used to account for unrecovered organic C.
• Soil organic matter percentage can be calculated by multiplying the estimated organic carbon percentage by 1.724
• For soils that are very high in organic carbon content, the Walkley & Black method may result in low test results, due to the incomplete oxidation of the organic carbon in the sample.
• So 100% of the total oxidizable organic carbon is not oxidized in this method.
• Smaller sample weights should be used for samples with very high carbon content.
• This method is for the determination of organic carbon in soils. It is not applicable to soils containing significant amounts of carbonized materials.

The correct answer is (A) ‐ (iv), (B) ‐ (iii), (C) ‐ (ii), (D) ‐ (i).

Key Points

• Helicitic mineral is a type of recrystallization structure where the poikiloblasts overgrow the pre-existing foliation appearing in twists and curves. This is akin to coral branching in terms of shape. This texture, therefore, indicates post-tectonic crystallization of poikiloblasts.
• Micaceous minerals form very thin layers that peel off or cleave very easily. They characteristically split into flexible sheets much like lamelae.
• Oolitic minerals occur in crystalline aggregates that are rounded and less than 4mm in size. Oolite is a sedimentary rock composed of ooids (ooliths), which are spheroidal grains with a nucleus and mineral cortex accreted around them, the sphericity of which increases with distance from the nucleus. For example oolitic hematite, chamosite etc.
• Stellate minerals are long thin crystals radiating outwards from a centre producing a star-like shape, such as astrophyllite, wavellite etc.

Explanation:

Air Quality Index:

• AQI is an overall scheme that transforms individual air pollutant (e.g. SO₂, CO, PM₁₀) levels into a single number, a simple and lucid description of air quality for the citizens.
• AQI relates to health impacts and citizens can avoid unnecessary exposure to air pollutants;
• AQI indicates compliance with National Air Quality Standards;
• AQI prompts local authorities to take quick actions to improve air quality;
• AQI guides policymakers in take broad decisions; and
• AQI encourages citizens to participate in air quality management.

AQI categories and range:

So the correct answer is option 2.

The correct answer is (A) ‐ (ii), (B) ‐ (i), (C) ‐ (iv), (D) ‐ (iii).

Key Points

Additional Information

• Hydropower projects are classified as large and small hydro projects based on their sizes.
• India is the world's seventh-largest producer of hydroelectric energy, with a total capacity of 47,057 MW.
• The Shivanasamudra hydroelectric power station was the first hydroelectric power facility.
• Tehri Dam is India's tallest structure, and Tehri Hydro Electric Power Plant is the country's tallest hydroelectric power facility.
• The Koyna Hydroelectric Project is India's largest completed hydroelectric power plant. It has a capacity of 1960 MW.

The correct answer is D, A, C, and B.

Key Points

• The greenhouse effect is the process by which solar radiation is absorbed by greenhouse gases rather than reflected back into space. This insulates the earth's surface and keeps it from freezing.
• A greenhouse gas (GHG) is a gas that absorbs and emits radiant energy in the thermal infrared spectrum, resulting in the greenhouse effect.
• Different GHGs are Water vapour, Carbon dioxide (CO₂), Methane (CH₄), Nitrous oxide (N₂O), CFCs, HFCs, Perfluorocarbons and Tropospheric ozone.
• These GHGs have a different lifetime for which they can remain in the atmosphere.

The correct answer is E, A, B, C, D.

Key Points

• Net Heating Value (NVH) is the potential energy available in a fuel sample that is the heat generated by the complete combustion of a unit volume of gas, excluding heat recoveries by condensing the water vapour formed.

Additional Information

• High Heating Value (HHV) refers to the energy released in combustion when condensing the water vapour resulting from the combustion, causing latent heat evaporation as a result.

The correct answer is Statement I is true but Statement II is false.

Key Points

Properties of a good measure of dispersion:

• It should be simple to understand.
• It should be easy to compute.
• It should be rigidly defined.
• It should be based on each and every point of distribution.
• It should have sampling stability.
• It should not be unduly affected by extreme items.

Quartile deviation:

• Quartile deviation is an absolute measure of dispersion.
• Quartile deviation gives the average amount by which the two quartiles differ from the median. The median ± quartile deviation covers exactly 50% of the observations.
• Quartile deviation ignores 50% of items i.e., the first 25% and the last 25%. As the value of quartile deviation does not depend upon every item of the series, therefore, it cannot be regarded as a good method of measuring dispersion.

Mean deviation:

• ​The mean deviation is also known as the average deviation. It is the average difference between the items in a distribution and the median or mean of that series.
• It is based on each and every item of data and is less affected by the value of extreme items. Therefore, is comparatively a better measure of deviation than range and quartile deviation.

 Therefore, statement I is true but statement II is false.

The correct answer is Both Statement I and Statement II are true.

Key Points

• A distribution that is non-symmetrical is called skewed distribution. The curve stretches to one side of the centre.

          The distribution can be of two types: 1. Positively Skewed distribution 2. Negatively Skewed distribution

1. Positively Skewed distribution: Here greater range of values spread from the right side of the curve. Therefore, the long tail is towards the right side. Log-normal distributions are positively skewed due to low mean values and high variances in the random variables.
2. Negatively Skewed distribution: Here greater range of values spread from the left side of the curve. Therefore, the long tail is towards the left side.

Therefore, both statements are true.

The correct answer is A is true but R is false.

Key Points

• Hybrid cars have both an Internal Combustion Engine (ICE) and an onboard electric power system made up of a generator, electric motor and battery storage.
• ICE runs on gasoline or diesel or other alternative fuels like natural gas, propane, biodiesel and ethanol.
• When electric power is put into a motor/generator, it acts as an electric motor delivering mechanical shaft power; when shaft power is put in, it acts as a generator delivering electricity.
• For slow-speed driving, the car can run entirely on its batteries.
• When cruising along, the ICE and motor/generator provide power, with perhaps some shaft power driving a small additional generator to recharge the batteries.
• When brakes are applied, the electric motor becomes an electric generator that recharges the batteries.

​Therefore, assertion (A) is true but reason (R) is false.

The correct answer is (A), (C) and (D) Only.

Key Points

• Biological Diversity Act which was passed in 2002, aims to conserve biological resources, manage their sustainable use, and enable fair and equitable sharing of benefits arising from the use and knowledge of biological resources with local communities.

The act called for a three-tiered structure to govern:

• The National Biodiversity Authority
• The State Biodiversity Boards
• The Biodiversity Management Committees​

The National Biodiversity Authority (NBA) was established in 2003 by the Central Government to implement India’s Biological Diversity Act (2002).

• It is a Statutory body.
• The NBA has its Headquarters in Chennai, Tamil Nadu, India.
• The State Biodiversity Boards are established by the State Governments in accordance with Section 22 of the Act.

Therefore, only statements A, C, and D are correct.

The correct is (B) and (D) Only.

Key Points

• Eco mark is a certification mark issued by the Bureau of Indian Standards (BIS) for products that are environmentally safe and meet the BIS's standards.
• It was issued by the Ministry of Environment and Forest in 1991.
• In India, the Ecomark symbol is an earthen pot or 'Matka'.

Additional Information

• In India, the Ecomark label is given to environmentally friendly products. It is a certification mark that is available for products in approximately 16 categories.
• Soaps and detergents, paints, food items, lubricating oils, packing/packaging materials, architectural paints and powder coatings, batteries, electrical and electronic goods, food additives, wood substitutes, cosmetics, aerosols and propellants, plastic products, textiles, fire-extinguisher, leather, and coir & coir products are among the product categories covered by the scheme.

Therefore, only statements B and D are correct.

The correct answer is (A) and (C) Only.

Key Points

Measure of Central Tendency:

In any distribution, when the original item differs in size the value of arithmetic mean (AM), geometric mean (GM), and harmonic mean (HM) would also differ and will be in the following order:

• ​AM ≥ GM ≥​ HM
• The equality sign holds only if all the numbers x₁, x₂.....x_n are identical.

Regression:

• The coefficient of X in the line of regression of Y on X is called the regression coefficient of Y on X. It represents a change in the value of a dependent variable (Y) corresponding to a unit change in the value of an independent variable (X).
• The regression coefficient is independent of the change of the origin. This implies that there will be no effect on the regression coefficients if any constant is subtracted from the value of x and y.

Correlation:

• Correlation is a statistical measure that describes the size and direction of a relationship between two or more variables.
• A correlation between variables, however, does not automatically mean that the change in one variable is the cause of a change in the values of other variables. Therefore, a correlation between two variables does not imply causation.

Therefore, only statements A and C are correct.

The correct answer is (A), (B) and (D) only. 

Key Points

Consider the first sentence of the first paragraph:

• ​According to a study published recently in the journal Nature Climate Change, while black carbon has a significant effect on snow darkening and the resultant melting of snow, dust particles transported from as far as Saudi Arabia that gets deposited in the Western Himalayan Region (WHR) have a significant role to play in melting of snow, particularly at higher elevations.

​Consider the second sentence of the second paragraph:

• ​This is in addition to snow‐melt caused by warming due to climate change.
• ​Thus it can be concluded that the reasons for the melting of snow in the Himalayas are black carbon deposition, deposition of dust particles, and climate change.

​Therefore, the correct answer is (A), (B), and (D) only. ​

The correct answer is 3‐5 km.

Key Points

Take a look at the second last sentence of the second paragraph:

• ​As the elevation increases, the influence of dust comes greater than black carbon and this coincides with the maximum intensity of snow melt reduction seen at 3‐5 km elevation.

So maximum snow melting rate occurs at an elevation of 3-5 km.

Therefore, the correct answer is 3‐5 km.

Additional Information

• Dust particles and black carbon deposition have a cumulative effect on the melting of snow i.e., both increase the rate of snow melting in the Himalayas.

The correct answer is Both A and R are true and R is the correct explanation of A.

Key Points

• Examine the third sentence of the second paragraph:
• Though black carbon has a larger snow albedo darkening effect than dust due to a larger mass absorption efficiency, the study found that the radiative effects of dust deposited on snow are comparable to black carbon in the WHR at higher elevations.
• ​This proves our assertion is true which states that the reduction in snow albedo is more due to black carbon than dust.
• Examine the fourth sentence of the second paragraph:
• ​This is mainly because the deposition of the dust by mass is 100‐1000 times more than black carbon.
• ​This means that although more dust gets deposited in the Himalayas than black carbon, due to its higher mass absorption efficiency i.e., absorbing more solar radiation per unit mass than that of dust particles, black carbon causes more melting of snow than dust.
• This proves our reason is true and also proves that the reason is the correct explanation of the assertion.

Therefore, the correct answer is Both A and R are true and R is 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

• Analyze the third sentence of the second paragraph:
• Though black carbon has a larger snow albedo darkening effect than dust due to a larger mass absorption efficiency, the study found that the radiative effects of dust deposited on snow are comparable to black carbon in the WHR at higher elevations.
• This proves our assertion is true which states that the radiative effects of dust deposited on snow are comparable to black carbon in the WHR at higher elevations.
• By analysing the same sentence again, we can say that both black carbon and dust have a darkening effect on the snow which proves our reason is true.
• But the reason does not correctly explain the assertion as their radiative effect is comparable only because more amount of dust gets deposited in the west Himalayan region i.e., almost 100-1000 times the mass of black carbon and not because black carbon and dust both darken the snow causing its melting.

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

The correct answer is Black carbon and dust are competing agents in the melting of snow packs.

Key Points

• Take a look at the first sentence of the first paragraph:
• According to a study published recently in the journal Nature Climate Change, while black carbon has a large effect on snow darkening and the resultant melting of snow, dust particles transported from as far as Saudi Arabia that gets deposited in the Western Himalayan Region (WHR) have a large role to play in melting of snow, particularly at higher elevations.
• ​Take a look at the fourth sentence of the second paragraph:
• ​Though black carbon has a larger snow albedo darkening effect than dust due to a larger mass absorption efficiency, the study found that the radiative effects of dust deposited on snow are comparable to black carbon in the WHR at higher elevations.
• ​​Take a look at the fifth sentence of the second paragraph:
• ​This is mainly because the deposition of the dust by mass is 100‐1000 times more than black carbon.
• ​Take a look at the last sentence of the second paragraph:
• ​Between these two black carbon mainly contributes to snow melt at lower elevations while dust is the major contributor to snow melt at higher elevations.
• ​By analyzing these sentences and the passage as a whole, we can see that it is both black carbon and dust which is transported from far-off places like Saudi Arabia and get deposited in the Western Himalayan Region and act together in the melting of snow. While the black carbon melts the snow at the lower elevations usually, the dust gets deposited at higher altitudes and causes the melting of snow there.
• It can also be concluded that although more amount of dust gets deposited than black carbon in the Himalayas, due to the larger mass absorption efficiency of black carbon, it causes more melting than the dust.

​Therefore, the finding of the passage is that black carbon and dust are competing agents in the melting of snow packs.

Explanation:

Aggressive/Scaling Water:

• A particular feature of calcium bicarbonate only exists in the dissolved form. When it precipitates, it does so in the calcium carbonate form, one that is only slightly soluble and it can only remain in the water when it is balanced out by available CO₂.

Ca [HCO₃]₂

CaCO₃ + CO₂ + H₂O

• As the CO₂ content has an influence on pH, there will also be a pH value for the equilibrium between this water and the calcium carbonate (Langelier pH or saturation pH written as pHs).

Therefore, we can "classify" water on this basis as follows,

• If pH > pHs, water will tend to deposit CaCO₃ which is then termed scale forming.
• If pH < pHs, water will tend to dissolve CaCO₃ and is then termed aggressive.

Hence, option 1 is the correct answer.

Explanation:

Topsoil:

• It is the uppermost layer of the soil. It has a high level of organic matter and microbial activity.
• The depth of the topsoil usually extends up to 5-10 inches. This occupies O or A Horizon.
• Formation of topsoil typically takes around more than 100-500 years which is an incredibly slow process. Hence option 4 is the correct answer.

Soil Formation:

• It is a complex natural process and formed through different series of development.
• This weathering of rock into the soil is called the process of pedogenesis.
• There are five factors that influence the formation of soil: parent material, climate, biota, topography, and time.
• The various soil-forming processes such as soil enrichment (organic and inorganic matter added to the soil), removal (leaching), translocation (upward and downward movement within the soil), and transformation (one form of compound to another) are involved.

Concept-

Different factors such as distance from the shore, penetration of light, depth of water, plant and animal species, etc. determine the following zones found in the pond ecosystem:

• Littoral zone: It is the zone closer to the shore. It contains shallow water and allows easy penetration of light. Rooted plant species occupy it. Animal species include reeds, crawfish, snails, insects, etc.
• Limnetic zone: The limnetic zone refers to the open water of the pond with an effective penetration of light. This zone is dominated by phytoplankton. Animal species mainly include small fishes and insects.
• Profundal zone: The region of a pond below the limnetic zone is called a profound zone with no effective light penetration. Some amphibians and small turtles occupy it.
• Benthic zone: The bottom zone of a pond is benthic and is occupied by a community of decomposers. The decomposers are called benthos.

Concept:

Biogas:

• The byproducts of anaerobic digestion of organic materials are commonly referred to as Biogas because of the biological nature of the gas production.
• Biogas technology refers to the production of a combustible gas (called biogas) and a value-added fertilizer (called slurry or sludge) by the anaerobic fermentation of organic material under certain controlled conditions.
• Biogas is produced by microbial activities and can be used only at the place where it is produced.
• The main constituents of biogas are - 
• Methane (CH₄) (55-65 %)
• carbon dioxide (CO₂) ( 30-45 %)
• Traces of Hydrogen Sulfide (H₂S)
• Gases like methane, hydrogen, and carbon monoxide may all be burned or oxidized.
• The use of biogas as fuel is made possible by this energy release.
• It is used as a fuel, for instance, in cooking for heating purposes, and employed in a gas engine.

The correct answer is option 2.

The correct answer is 1976.

Key Points

• India became a party to CITES in the year 1976. 
• ​A resolution was adopted in 1963 at the IUCN meeting and CITES came into force on 1 July 1975.
• CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora)
• It is an international agreement between governments.
• Its aim is to ensure that international trade in specimens of wild animals and plants does not threaten the survival of the species.
• It provides the framework for the countries and the parties have to prepare domestic laws for implementation.
• It prepares a list of region wise species to be protected.
• CITES works by subjecting international trade in specimens of selected species to certain controls.
• All import, export, re-export and introduction from the sea of species covered by the Convention has to be authorized through a licensing system.
• Headquarters: Geneva, Switzerland.
• Members: 184
• Secretary-General: Ivonne Higuero

Concept Used:

A continuous variable is a variable whose value is obtained by measuring, i.e., one which can take on an uncountable set of values.

In contrast, a variable is a discrete variable if and only if there exists a one-to-one correspondence between this variable and {\displaystyle \mathbb {N} }

,

Since time clocked is only measured at .01 seconds interval.

Hence, the time clocked by an athlete in a 100 m race is an example of a discrete variable.

Explanation

The coefficient of determination R² is the ratio of the explained variation to the total variation.

Given values:

Explained sum of squares or Explained variation = 75

Unexplained sum of squares or Unexplained variation =25

The total variation = 75 + 25 = 100.

Therefore, the value of R² = 75/100 = 0.75.

Hence, option 4 is the correct answer.

Explanation:

Incineration:

It is a method of thermal treatment of waste materials. It converts waste materials into ash, flue gas, and heat. Hence, C is correct.

Advantages

Reduced Quantity of Waste: It decreases the quantity of waste by as much as 95% and reduces the solid quantity of the original waste by as much as 80-85%. Hence, B is correct.

• Efficient Waste Management: Incineration can burn up to 90% of the total waste generated and sometimes even more.
• Production of Heat and Power: Incineration plants generate energy from waste that can be used to generate electricity or heat.
• Reduced Reliance on Transportation: waste does not have to be driven long distances for dumping.
• Better control over Odour and Noise: waste gets burnt inside a facility where the byproducts of the incineration process can be controlled.
• Prevents the Production of Methane Gas.
• Eliminates Harmful Germs and Chemicals.

Disadvantages

• It requires high operating costs and is expensive. Hence, D is not correct.
• It leads to significant levels of pollution. The smoke produced during the burning process may include acid, dioxin, particulates, heavy metals, etc. These gases are poisonous to the environment and cause health effects. Therefore, it is not considered a clean process. Hence, A is not correct.
• Incineration does not encourage recycling processes.

Therefore, option 2 is the correct answer

Concept:

Iron:

• A commonly used method for the determination of trace amounts of iron involves the complexation of Fe²⁺ with 1,10-phenanthroline to produce an intensely red-orange colored complex and further test procedures are carried out to measure the amount of Iron.

Dissolved Oxygen-

• It is measured using Winkler's method.
• Manganous Sulphate is used as a reagent here.

Calcium-

• Murexide, also known as ammonium purpurate or MX, is the ammonium salt of purpuric acid.
• This metallochromic indicator undergoes a color change in the presence of calcium, so it is used to measure Calcium in water.

Sulphate-

• Test of sulphate is based on the reaction of soluble sulphate with barium chloride in presence of dilute hydrochloric acid to form barium sulphate which appears as solid particles (turbidity) in the solution.

The correct answer is B > C > D > A.

Key Points

• Spatial resolution refers to the distance represented by a pixel in an image.

Therefore, the decreasing order of spatial resolution of some Indian satellites is Oceansat - 2 OCM > Resourcesat -2 AWIFS > IRS - ID LISS - 3 > Cartosat - 2 PAN.

The correct answer is A < C < D < B.

Key Points

• Albedo is the measurement of the reflectivity of sunlight by any object.
• Objects reflecting more sunlight have high albedo while those reflecting less have a low albedo.

Therefore, The increasing order of albedo of natural surfaces is Oceans < Grass < Desert < sand < Fresh snow.

Additional Information

• Objects with higher albedo are cooler in temperature and while those with lower albedo are hotter in temperature.
• The albedo of a given region depends on soil composition and moisture, vegetation types, level of urbanization, etc.
• Earth’s overall albedo is measured to be 30%.

The correct answer is: (D), (B), (C), (A)

Key Points

Metamorphic rocks:

• Derived from the Greek word, ‘meta’- change and ‘morphos’ meaning form.
• These rocks are formed by changing the mineral in the presence of high temperature and pressure.
• Both igneous and sedimentary rocks can become metamorphic rocks.

Metamorphic grade:

• It refers to the range of metamorphic changes the rock undergoes.
• It progresses from little metamorphic change (low grade) to significant metamorphic change (high grade).
• Low-grade metamorphism begins at temperatures and pressures just above sedimentary rock conditions. In the above option, ns Shale is the sedimentary rock and starts with low-grade and gradually high-grade metamorphism.

Therefore, the ascending order sequence of metamorphism grade would be **shale **→ slate → phyllite → schist → gneiss.

Hence, option 4 is the correct answer.

Additional Information

Metamorphic  Rock	Origin Rock
Marble	Limestone (Carbonate Sedimentary rock)
Slate	Shale (Clastic Sedimentary rock)
Gneiss	Granite (Intrusive igneous rock)
Quartzite	Sandstone (Clastic Sedimentary rock)

Concept-

• The compost which is to be used as fertiliser for food crops should abide by the more stringent FCO, 2009, while compost used as a soil conditioner and for other purposes should at least meet the requirements of SWM Rules, 2016.
• Phosphatic fertiliser is in short supply in the country. The use of phosphate-rich organic manure (PROM) can reduce the use of phosphatic fertilisers to some extent; PROM is formed by the mixing of rock phosphate with MSW-derived compost.

The FCO, 2013 specified quality standards for PROM, while retaining the standards specified in FCO, 2009 for organic compost.

So the decreasing order is Copper > Lead > Chromium > Cadmium.

The correct answer is Article 51A(g).

Key Points

• Article 51A(g) of the Indian Constitution
• **“It shall be duty of every citizen of India to protect and improve the natural environment including forests, lakes, rivers and wild life and to have compassion for living creatures.”**​
• The Directive principles under the Indian constitution directed towards ideals of building welfare state. Healthy environment is also one of the elements of welfare state.
• Article 42 ​
• The State shall make provision for securing just and humane conditions of work and for maternity relief.
• Article 21
• No person shall be deprived of his life or personal liberty except according to procedure established by law.

Important Points

• Articles 36-51 under Part-IV of the Indian Constitution deals with Directive Principles of State Policy (DPSP).
• They are borrowed from the Constitution of Ireland, which had copied it from the Spanish Constitution.
• DPSP are non-binding in nature which means they are not enforceable by the courts for their violation.
• These principles emphasize that the State shall try to promote the welfare of the people by providing them basic facilities like shelter, food and clothing.
• It denotes the ideals that the State should keep in mind while formulating policies and enacting laws.

The correct answer is B, E, D, A, and C.

Key Points

• The texture of the soil is one of the primary deciding features of the porosity of soils. The amount of organic matter present in the soil is directly proportional to its water-holding capacity.
• Clay has the highest proportion of organic matter. It has the highest porosity and lowest permeability. Therefore, the wet clods formed are highly stable.
• Primary soil particles are held together by cohesive forces, and secondary particles and organic matter form soil aggregates. Aggregate stability is the measure of the ability of soil aggregates to bind together and resist degradation or breaking apart.
• Organic matter increases aggregate stability. Since clay has the highest amount of organic matter, therefore, it has the highest aggregate stability.
• Since sandy loam has the lowest percentage of organic matter, therefore, its aggregate stability is lowest i.e., the stability of micro-aggregates is lowest.

The amount of organic matter and porosity vary in the order of:

• Clay > Clay loam > Silt loam > Loam > Sandy loam

Therefore, the stability of wet clods of given texture classes are in the order of:

• Clay > Clay loam > Silt loam > Loam > Sandy loam

Explanation:

Bio-medical waste means any waste, which is generated during the diagnosis, treatment, or immunization of human beings or animals or research activities pertaining thereto or in the production or testing of biological or health camps.

Hence, Option 4 is the correct answer.

Explanation:

Human Evolution:

• It is the process by which human beings occupied the earth through various stages of living.
• Homo sapiens, first evolved 315,000 years ago.
• During the Miocene Epoch which is 23 million to 5.3 million years ago, we were the probable beginners of life and developed into modern humans only recently in the Pleistocene Epoch is 2.6 million to 11,700 years ago.
• Pastoralist societies are people who lived in the countryside during the period of 8500-6500 B.C.
• Humans started growing cultivation and evolved as an agrarian society ty during the Neolithic period around 10,000 -8,000 years ago.
• For survival during the earlier times of 12,000 years ago, humans were occupied with hunting and gathering which is a subsistence lifestyle for food.
• Industrial society developed as a modernized era of human society during recent times where machines were playing the important role in the production process.

Hence, option 3 is the correct answer.

Explanation

Green belt movement:

• It was founded in the year 1977 under the auspices of the National Council of Women of Kenya (NCWK).
• It is an environmental organization that empowers communities, particularly women, to conserve the environment and improve livelihoods.
• Wangari Maathai was the founder of this movement and movement and he got the Nobel Peace prize in the year 2004. She authored four books namely The Green Belt Movement, Unbowed: A Memoir, The Challenge for Africa; and Replenishing the Earth.
• The well-known work of this organization is the planting of trees and now addressing the problem of global deforestation.
• This movement aims at organizing women in rural Kenya to plant trees, combat deforestation, restore their main sources of fuel for cooking, generate income and stop soil erosion.

Hence, option 1 is the correct answer.

Explanation:

Given values are,

• Latitude- 30⁰ (Sin 30⁰ = 0.5)
• Pressure- 1.0 mb (1 mb x 100 = 100 Pa)
• Density of Air = 1.25 kg/m³
• Distance = 100 km (100 km x 1000 = 100000 m)

Also,

​​The angular velocity of Earth= 7.3 x 10^-5 rad/s

Geostrophic wind velocity (Vg)  = $\frac{Pressure(Pa )}{ (2 \ \times Angular\ velocity\ of \ Earth) \times\ Density\ of \ Air \ \times Latitude \ \times \ Distance(m)}$

V_g = $\frac{100}{ (2 \times 7.3 \times 10^{-5}) \times\ 1.25\ \times 0.5\ \times \ 100000}$

V_g = 10.95 = ~11 m

Hence, option 1 is the correct answer.

Explanation

Alpha Diversity (α)

• It refers to the species diversity within a community.
• This generally describes the size or a defined unit of an ecosystem.
• For example Species present in a patch of a grassland ecosystem.

Beta Diversity (β)

• It refers to the species diversity between two communities.
• It is the ratio between regional and local species diversity.
• A geographical area will act like a barrier between two like a river or mountain.
• For example Diversity between woodland and hedgerow habitats.

Gamma Diversity (ϒ)

• It refers to the species diversity of two or more ecosystems.
• It is a large-scale study of a biome or landscape.
• For example Diversity in the entire mountain slope

The interrelationship among them is represented as,

β = $\frac{\gamma }{\alpha}$ (or) ϒ= β x α,  

Hence, option 1 and 2 is the correct answer.

Explanation:

Bacterial Identification:

• The isolated bacteria are further processed through various methods to identify their number and type.
• These methods include the Biochemical method, Serological tests, Molecular techniques, etc.
• Molecular Methods include DNA-DNA hybridization, DNA or RNA bases sequencing, Polymerase chain reaction PCR, real-time PCR, etc.

MPN:

• The most probable number (MPN) is a technique for estimating the viable numbers of bacteria by multiplying the inoculation broth in a series of dilutions.
• This test is completed in three steps. These include the presumptive test, the confirmed test, and the completed test.

Hence, option 1 is the correct answer.

Concept-

• The geothermal gradient is defined as the increase in temperature with depth in the Earth.
• In normal continental crust, a typical geothermal gradient within the first 3 to 5 kilometers (2 or 3 miles) of Earth’s surface is about 25°C/km.
• This gradient, however, is not sustained but decreases to no more than about 16°C/km at a depth of 40 km.

• The temperature profile of the Earth's layers. Temperature increases with depth
• The interior of the Earth is extremely hot and reaches temperatures over 5000°C near the core, which is not much colder than the surface of the Sun.

Concept-

The carbon content in coal is 0.81.

Carbon content in coal describes the amount of carbon in 1 kg of coal.

Here in 1 kg of coal, carbon content is 810 gm.

C + O₂ → CO₂

12 gm of carbon reacts with 32 gm oxygen to form 44 gm of CO₂.

So 810 gm of carbon will form  = $\frac{44\ \times \ 810}{12}$ = 2970 gm of CO₂.

So the amount of CO2 produced will be almost -3 kg.

Concept-

• The ministry of environment, forests and climate change (MoEFCC) has taken a decision that will prove disastrous for people living near power plants, according to environmentalists.
• It has done away with the condition for power plants to use.
• The Ash content of coal produced in the country is generally 25 to 45 % whereas the average ash content of imported coal varies from 10 to 20 %.
• Indian Coal has comparatively higher ash content than imported coal due to the drift theory of the formation of coal deposits in India.
• Coal seams formed due to drift theory contain higher ash as compared to the in-situ theory of formation.
• As per the Ministry of Environment and Forest & Climate Change (MOEF&CC) stipulation, coal-based thermal power plant (situated beyond 500 km from the pit-head) be supplied with, and shall use, raw or blended or beneficiated coal with ash content not exceeding thirty-four percent, on a quarterly average basis.
• Coal Companies are supplying coal to their customers maintaining an ash percentage below 34% on a quarterly average basis as per the aforesaid MOEF&CC stipulation.

The correct answer is (A), (B) and (D) Only.

Key Points Characteristics of energy crops:

1. ​Energy crops are one of the primary sources of biomass-based feedstocks studied for biofuel production.
2. They are low-cost, low-maintenance crops grown solely for the production of energy through combustion (not for food).
3. They grow at a very fast rate.
4. These crops are transformed into solid, liquid, or gaseous fuels like pellets, bioethanol, or biogas.
5. Energy crops require low establishment inputs, and low fossil fuel inputs, be adaptable to marginal lands and provide high biomass and energy yields that are expected to help reduce global warming and combat climate change (GCC).
6. Highly erodible, flood-prone, compacted, saline, acidic, contaminated, or sandy soils, reclaimed mine soils, urban marginal sites, and abandoned or degraded croplands are examples of marginal or degraded lands suitable for energy crops.
7. Energy crops with a higher proportion of fibrous material (lignocellulose) have the highest calorific value, making it advantageous to maximise the yield of this plant fraction for energy and fuel production.
8. Fuel wood (dedicated energy crop) generates usable heat for the residential, commercial, and electric utility sectors.
9. Examples: Maize or sweet sorghum and herbaceous and woody plants, such as miscanthus (Miscanthus giganteus), switchgrass (Panicum virgatum), kenaf (Hibiscus cannabinus), reed canary grass (Phalaris arundinacea) or giant reed (Arundo donax), and eucalyptus (Eucalyptus globulus).

Therefore, statements A, B, and D are correct.

The correct answer is (A), (B) and (C).

Key Points

• Isokinetic air sampling is a method of collecting airborne particulate matter in which the collector is designed in such a way that the airstream entering it has the same velocity as the air passing around and outside the collector.

 Principles of isokinetic air sampling:

• The aim is to capture particles that pass through a defined area for a specified amount of time without interfering with their paths. That is why the inlet of the air sampler is kept against the prevailing winds.
• The velocity of the air entering the sampling probe nozzle equals the velocity of undisturbed air at that point.
• The air is disturbed as little as possible so that the same particles (no more and no less) enter the nozzle as would have passed through the area of the nozzle if it did not exist.

Therefore, all the statements about isokinetic air sampling are correct.

The correct answer is (A) ‐ (iv), (B) ‐ (iii), (C) ‐ (i), (D) ‐ (ii)

Key Points

Additional Information

• Circannual rhythms are self-sustaining endogenously driven biological oscillations that last for about a year in the absence of environmental cycles.
• Examples: population rhythm in carpet beetles, the urge to migrate in birds, hibernation cycles in ground squirrels and cycles of reproductive activity and moulting in ungulates etc.
• Circadian rhythms are 24-hour cycles of physical, mental, and behavioural changes.
• Examples: the sleep-wake cycle, the body temperature cycle, the cycle in the secretion of hormones etc.

The correct answer is Both Statement I and Statement II are false.

Key Points

• Ethanol (CH₃CH₂OH) is also known as grain alcohol. It is widely used as an oxygenate to reduce CO emissions, in which case the gasoline/ethanol mixture is usually referred to as gasohol.
• Ethanol contains less energy per gallon than gasoline. Blending ethanol and gasoline at a ratio of 85% to 15% (E85), the resultant fuel is nearly 30% less powerful than pure gasoline. The energy density of E85 is 22.8 MJ/L.
• There is a huge difference between the energy density of pure gasoline and ethanol. The energy density of ethanol is 21 MJ/L while that of pure gasoline is 32.2 MJ/L.

Therefore, both statements I and II are false.

The correct answer is (A), (C), and (E) Only.

 Key Points

• Project Elephant was launched in 1992 by the Ministry of Environment and Forests, Govt. of India for free-ranging populations of wild Asian Elephants.
• The project is mainly implemented in 16 states, including Arunachal Pradesh, Assam, Andhra Pradesh, Chhattisgarh Jharkhand, Kerala, Karnataka, Meghalaya, Maharashtra, Nagaland, Orissa, Tamil Nadu, Uttaranchal, Uttar Pradesh, and West Bengal as per 2019 and currently updated to 22 States.
• There are around 32 Elephant Reserves across the country, the first one being the Singhbhum Elephant Reserve of Jharkhand.
• Project Elephant has been formally implementing the MIKE (Monitoring of Illegal Killing of Elephants) program of CITES in 10 Elephant Reserves since 2004.
• There are 88 Elephant corridors throughout India majorly spread across Southern India, Central India, and North-Eastern states.
• The Ministry of Environment and Forests, in collaboration with the Wildlife Trust of India, has launched the Hathi Mere Sathi campaign The campaign aimed to raise public awareness and foster friendships between elephants and the local population.

Therefore, statements A, C, and E are correct.