UGC NET Paper 2: Environmental Science 29th Sep 2020 Shift 2 (Previous Year Paper)

The correct answer is the Discrete variable.

Key Points

Variables: Variables are measurable characteristics that can be numerically expressed in some terms of some units. These are quantities that are capable of being measured by quantitative methods directly. For example, the height in inches, weight in kg, marks in examination, etc.

1. ​​Discrete Variables (Discontinuous/meristic): These are the quantities that can be measured in whole integral values. It does not take a fractional value. For example, the number of marks in an examination.
2. Continuous Variables: These are the quantities that can take any value in a specified range. Thus it can take integral and fractional values both. For example. Heights, weights, etc.
3. Nominal: Data that can't be ordered or have two or more categories. For example, the colour of hair, marital status (married, separated, divorced), nature of the disaster (fire, accident, theft), etc.
4. Ordinal: Data that can be ordered in terms of their characteristics. For example, tidiness (messy, fairly, very neat, etc).

Therefore, the number of marks scored by students appearing in the examination is an example of discrete variables.

The correct answer is 200 meters.

Key Points

• Solid Waste Management Rules 2016 specifies the criteria for site selection of landfills as follows:

 

 

 

 

 

Therefore, according to Solid Waste Management Rules 2016, a landfill site should be 200 meters away from a pond.

The correct answer is Our Common Future.

Key Points

• The Brundtland Commission was created by the United Nations to suggest measures to protect the human environment and natural resources and prevent the deterioration of economic and social development.
• It is formally called World Commission on Environment and Development.
• Its report was titled as "Our Common Future".
• It was released in 1987.
• The Brundtland Commission’s characterization of ‘sustainable development’ is the development that meets the needs of the present without compromising the ability of future generations to meet their own needs.
• The prominence given to ‘needs’ reflects a concern to eradicate poverty and meet basic human needs, broadly understood.

Therefore, the Brundtland Commission Report was entitled as Our Common Future.

The correct answer is 'Statement I is incorrect but Statement II is true'.

Key Points

Statement I: In clear water, the reflectance is very high in the visible region of the electromagnetic spectrum is incorrect because,-

• Reflectance refers to the fraction of incident electromagnetic power that is reflected at an interface.
• In clear water, the majority of light in the visible region is transmitted rather than reflected.
• Visible light (wavelengths roughly between 400-700 nm) penetrates and is absorbed or scattered within water, leading to low reflectance.
• Reflectance is typically higher in the ultraviolet (UV) or near-infrared (NIR) regions rather than the visible region in aquatic environments.
• Thus, the statement that reflectance is very high in the visible region for clear water is not accurate.

Statement II: Pure water strongly absorbs radiation from the mid-infrared spectral region is true because,-

• The mid-infrared (mid-IR) region spans wavelengths roughly between 2.5 to 25 micrometers (μm).
• Pure water has strong absorption bands in the mid-IR region, particularly around 3 micrometers (O-H stretch) and 6 micrometers (H-O-H bending).
• This strong absorption is due to the vibrational modes of water molecules which are active in the mid-IR range.
• As a result, pure water is an effective absorber of mid-IR radiation, which is why this statement is true.

Additional Information

• Water's absorption characteristics change across the electromagnetic spectrum, making it transparent to certain wavelengths (like visible light) and absorptive to others (like mid-IR).
• Reflectance and absorption properties of water are critical in various fields such as remote sensing, environmental monitoring, and optical instrument design.
• The study of spectral properties (how substances absorb, reflect, and emit light) helps in understanding the composition and physical properties of water bodies.

The correct answer is A and D only.

Key Points

Henry's law is a gas law that states that the amount of gas that is dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid when the temperature is kept constant. 

P = k_H.C

• 'P' denotes the partial pressure of the gas in the atmosphere above the liquid.
• 'C' denotes the concentration of the dissolved gas.
• 'k_H' is Henry's law constant of the gas.

The value of Henry's law constant of a gas is dependent on the following factors:

1. The nature of the gas.
2. The nature of the solvent.
3. Temperature and pressure.

The solubility of gases varies inversely with respect to temperature. As the temperature increases, the solubility of the gases in liquids decreases.

The solubility of any substance in any medium is dependent on the amount of solute and solvent involved.

Therefore, regarding the solubility of gases in water only statements A and D are correct.

The correct answer is 3 ∶ 2.

Key Points

Given:

• ​Combined mean = 48
• Mean of the first group = 40
• Number of items in the first set = m
• Mean of the second group = 60
• Number of items in the second set = n

Since we know that, 

$\bar{x_{12}} = \frac{n_1\bar{x_1}\ +\ n_2\bar{x_2}}{n_1\ +\ n_2}$

Where, 

$\overline{x_{12}}$ = Combined mean of two groups

n₁ = Number of items in first group

$\overline {x{_1}}$ = Arthmetic mean of first group

n₂ = Number of items in second group

$\overline {x{_2}}$ =  Arthmetic mean of second group

Therefore, 

$\overline {x_{12}} = {m\ \times \ 40 \ + \ n\ \times \ 60 \over m+n}$

 $48 = {m\ \times \ 40 \ + \ n\ \times \ 60 \over m+n}$

$48(m+n) = m40 + n60$

$48m - 40m = {60n - 48n }$

$8m = {12n}$             

${m\over n} = {3\over 2}$  

Therefore, the ratio m ∶ n is 3 : 2

The correct answer is To study the traditional knowledge systems for community participation in adaptation and mitigation strategies.

Key Points

• National Mission for Green India is one of the 8 missions of the National Action Plan for Climate Change launched in 2008.
• The objectives/goals of the Green India Mission are:
• Increased forest/tree cover on 5 million hectares of forest/non-forest lands and improved quality of forest cover on another 5 million hectares (a total of 10 million hectares).
• Improved ecosystem services including biodiversity, hydrological services and carbon sequestration as a result of the treatment of 10 million hectares.
• Increased forest-based livelihood income of about 3 million households living in and around the forests.
• Enhanced annual CO₂ sequestration by 50 to 60 million tonnes in the year 2020.

Therefore, to study the traditional knowledge systems for community participation in adaptation and mitigation strategies is not the part of objectives/goals of the National Mission for Green India.

Additional Information

• To study the traditional knowledge systems for community participation in adaptation and mitigation strategies is one of the objectives of the National Mission for Sustainable Himalayan Ecosystem.
• The 8 missions under the National Action Plan for Climate Change are:​

1. National Solar Mission
2. National Mission for Enhanced Energy Efficiency
3. National Mission on Sustainable Habitat
4. National Water Mission
5. National Mission for Sustaining Himalayan Ecosystem
6. Green India Mission
7. National Mission for Sustainable Agriculture
8. National Mission on Strategic Knowledge for Climate Change

Concept-

Standard deviation-

• Standard Deviation is a measure that shows how much variation (such as spread, dispersion, spread,) from the mean exists.
• The standard deviation indicates a “typical” deviation from the mean. It is a popular measure of variability because it returns to the original units of measure of the data set.
• Like the variance, if the data points are close to the mean, there is a small variation whereas the data points are highly spread out from the mean, then it has a high variance.
• Standard deviation calculates the extent to which the values differ from the average. Standard Deviation, the most widely used measure of dispersion, is based on all values.
• Therefore a change in even one value affects the value of the standard deviation. It is independent of origin but not of scale. It is also useful in certain advanced statistical problems.
• The formula for standard deviation = σ = $\sqrt {\frac{{\sum {x_i^2} }}{N} - {{\left( {\frac{{\sum {{x_i}} }}{N}} \right)}^2}}$

Given data and Calculation-

If ∑x = 230, ∑x2 = 6500

Numbers of observations, N = 10

σ = $\sqrt {\frac{{\sum {x_i^2} }}{N} - {{\left( {\frac{{\sum {{x_i}} }}{N}} \right)}^2}}$

 

σ = $\sqrt {\frac{{6500}}{{10}} - {{\left( {\frac{{230}}{{10}}} \right)}^2}}$ = 11

Concept:

Persistent organic pollutants (POPs):

• Persistent Organic Pollutants (POPs) are organic chemical substances, that is, they are carbon-based.
• They possess a particular combination of physical and chemical properties such that, once released into the environment, they:
• Remain intact for exceptionally long periods of time (many years);
• Become widely distributed throughout the environment as a result of natural processes involving soil, water, and, most notably, air;
• Accumulate in living organisms including humans, and are found at higher concentrations at higher levels in the food chain; and
• Are toxic to both humans and wildlife.
• Persistent organic pollutants (POPs) are chemicals of global concern due to their potential for long-range transport, persistence in the environment, ability to bio-magnify and bio-accumulate in ecosystems, as well as their significant negative effects on human health and the environment.
• The most commonly encountered POPs are Furans, organochlorine pesticides, such as DDT, industrial chemicals, polychlorinated biphenyls (PCB) as well as unintentional by-products of many industrial processes, especially polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF), commonly known as dioxins.

The correct answer is The range is independent of the change of origin but not of the scale.

Key Points

Dispersion is the measure of the variation of the items. In other words, the measurement of the scatteredness of the mass of figures in a series about an average is called a measure of variation or dispersion. The following are the methods of studying variation:

1. The range
2. The quartile deviation
3. The Mean deviation
4. The standard deviation
5. Variance.

Range is defined as the difference between the value of the smallest item and the value of the largest item in the distribution.

Range = L - S 

Where,  L = largest item

             S = smallest item.

• The range is independent of the change in origin. This implies that the value of the range remains constant if, in a series, a constant is added (or subtracted) to all observations.
• However, the range is affected by the change of scale. This implies that if all observations are multiplied or divided by a constant, then the value of the range will be affected.

Therefore, the correct statement is that the range is independent of the change of origin but not of the scale.

The correct answer is Three star.

Key Points

• GRIHA means Green Rating for Integrated Habitat Assessment.
• GRIHA is a rating tool that helps people assess the performance of their building against certain nationally acceptable benchmarks.
• It evaluates the environmental performance of a building holistically over its entire life cycle, thereby providing a definitive standard for what constitutes a 'green building'.
• It consists of 34 criteria categorized under 4 categories.
• Different levels of certifications (1 to 5 stars) are given based on the points earned.

 

 

 

 

 

Therefore, if a building has scored 57 points on a 100-point scale, it will be assigned 3 stars.

Additional Information

• It was amended in 2019.
• Now it consists of 30 criteria categorized under 11 sections.
• The new rating is done in the following manner:

Correct Answer: None of the given options is fully correct; only statements B and C are correct.

Ex-situ bioremediation is a soil treatment method where contaminated materials are removed from the site and treated elsewhere under controlled conditions. Common techniques include biopiles and windrow composting, which are widely used for hydrocarbon and organic contaminant degradation using aerobic microbes.

Key Points:

• Statement A – Incorrect:
• This statement refers to in-situ bioremediation, which occurs at or near the site of contamination without excavation.
• Ex-situ bioremediation involves removing contaminated material for off-site treatment or treatment in engineered systems nearby.
• Statement B – Correct:
• Biopiles and windrow composting are dominant ex-situ bioremediation techniques for treating hydrocarbon-contaminated soils.
• These systems optimize conditions for microbial degradation of contaminants.
• Statement C – Correct:
• Biopiles can be constructed to treat larger volumes of soil compared to windrow composting, which is less scalable.
• They use controlled aeration and moisture to enhance microbial activity.
• Statement D – Incorrect:
• Both biopiles and windrow composting are primarily aerobic processes, relying on oxygen to support microbial degradation.
• Anaerobic conditions can inhibit their efficiency unless specially designed for such conditions.

Additional Information:

• In-situ methods: bioventing, biosparging, phytoremediation.
• Ex-situ methods: landfarming, biopiles, windrow composting, slurry-phase treatment.
• Aerobic bacteria are more efficient at degrading petroleum hydrocarbons than anaerobic bacteria.

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

Key Points

• Diesel exhaust particles are produced when an engine burns diesel fuel.
• Because high compression ratios create high temperatures, NOx emissions can be relatively high.
• In addition, diesel engine exhaust has been labelled a probable human carcinogenic containing over 40 cancer-related substances including benzene, arsenic and formaldehyde.
• Exposure to diesel exhaust can have immediate health effects.
• It causes inflammation in the lungs which may aggravate chronic respiratory symptoms and increase the frequency or intensity of asthma attacks.
• NOx emitted can damage lung tissue causing chronic airway inflammation, hyper-secretion of mucus and airway constriction.
• Studies reveal that diesel exhaust particles enhance eosinophil adhesion to nasal epithelial cells and cause degranulation and airway hyper-responsiveness.

 Therefore, only A, B, D, and E are correct.

The correct answer is A and B only.

Key Points

• Phytoremediation involves the use of plants to remove and stabilize toxic substances from the environment.
• It takes advantage of the unique, selective and naturally occurring uptake capabilities of plant root systems, together with the translocation, bioaccumulation and pollutant storage/degradation abilities of the entire plant body.
• Compared to typical plants, hyperaccumulators accumulate 50 - 1000 fold higher heavy metals in their shoots than non-accumulators. Furthermore, they have remarkable effectiveness in binding or generating toxic metals into various chemical compositions, resulting in a decreased concentration of those toxic metals in the free ionic form.
• The phytoextraction technique can remove trace metals such as chromium, cadmium, copper, cobalt, silver, zinc, nickel, molybdenum, lead and mercury.
• Phytovolatilization has been proven effective to remove toxic metals like selenium and mercury.
• Toxic metals such as cadmium, nickel, and chromium can be easily removed using rhizofiltration processes.
• Phytoremediation of arsenic-contaminated areas requires the development of new plant varieties with enhanced uptake and accumulation of this metalloid in order to remove as much arsenic as possible from the environment.
• Although, a fern - Pteris vittata also known as the Chinese brake fern, holds promise for reducing both the time and cost associated with arsenic cleanup but arsenic can be best removed through traditional conventional methods.
• The harvested hyperaccumulating plants cannot be recycled in agriculture. It is required to safely dispose-off hyperaccumulators. The disposal technologies include incineration, composting, burial methods etc.

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

Key Points

• A plasmid is a small, circular, double-stranded DNA molecule that is distinct from a cell's chromosomal DNA.
• Plasmids naturally exist in bacterial cells, and they also occur in some eukaryotes.
• Plasmid genes frequently confer genetic advantages to bacteria, such as antibiotic resistance.
• Plasmids are used as tools for gene cloning, transfer, and manipulation.
• They are used experimentally for these purposes and are called vectors.
• These are critical in the context of environmental biotechnology because they frequently contain genes for degradative pathways.
• Many of these plasmids can move between bacteria where they replicate, allowing the metabolic capability they carry to be transferred.
• Bacteria are extremely promiscuous when it comes to sharing their DNA.
• Bacteria that live in a contaminated environment frequently develop additional degradative abilities.
• The source of that genetic information new to the organism, whether it is from internal DNA modification, transfer from other microbes, or free DNA in the environment, is a source of heated debate among microbiologists.

 Therefore, both Statement I and Statement II are correct.

The correct answer is A, C, and D only.

Key Points

• Base saturation refers to the percentage of cation exchange capacity occupied by a base cation. Base saturation is closely related to pH. To be more precise, base saturation is directly proportional to pH. It increases with an increase in pH. Moderately acidic soil has higher pH in comparison to strongly acidic soil. Therefore, the base saturation of moderately acidic soil is greater than strongly acidic soil.
• Free aluminium ions are the acidic cations present in the soil that lower the pH of the soil. Moderately acidic soil has a lower concentration of Al⁺³ in comparison to strongly acidic soils. Therefore, the abundance of Al+3 is less in moderately acidic soil.
• Under moderately acidic soil, the percentage of base saturation and pH values are somewhat higher. At such higher pH values, aluminium exists as aluminium hydroxy ions which act as exchangeable ions. On hydrolysis, aluminium hydroxy ios liberate H⁺ in soil solution.
• Exchangeable acidity refers to hydrogen and aluminium ions retained on the exchanged complex of the soil, that is on the surface of the soil colloids.

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

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

Key Points

• In some atmospheric conditions, the radius of the rotation becomes so small that the centrifugal force becomes quite strong in comparison with the Coriolis force.
• This is particularly where the Coriolis force is quite small, to begin with.
• In this case, the pressure gradient force is nearly balanced by the centrifugal force alone.
• When this occurs, the wind is said to be cyclonic.
• In other words, cyclonic wind exists when the pressure gradient force is balanced by the centrifugal force.
• Air spirals in towards the centre in a counter-clockwise pattern in the northern hemisphere and out of the top in opposite direction.
• They blow clockwise in the southern hemisphere.
• This can be explained because of the Coriolis effect.
• Due to the rotation of the earth, winds do not move perpendicular to the pressure belt. They are rather deflected from their original path.
• In the northern hemisphere, they get deflected to the right of their path (counter-clockwise) and in the southern hemisphere to the left of their path. It is called Ferrel's law.
• Buys Ballot's law states that in the northern hemisphere if you stand with your back to the wind, low pressure will be found to your left and high pressure to your right. In the southern hemisphere, the situation is reversed.

Therefore, both Statement I and Statement II are correct.

The correct answer is B, C, A.

Key Points

• According to Clarke and Washington, igneous and metamorphic rocks comprise 95% volume of the earth's crust.
• Sedimentary rocks comprise just 5% volume.
• About 65% of the earth's crust by volume consists of igneous rocks.
• Of these, 66% are basalt and gabbro, 16% are granite and 17% grandiorite and diorite. Only 0.6% are syenite and 0.3% are ultramafic.

Therefore, the correct increasing order of rocks by percent volume in the earth's crust is Sedimentary rocks < Metamorphic rocks <  Igneous rocks.

The correct answer is A and D only.

Key Points

Characteristics of prsticides:

• Pesticides are the chemical compounds that are used to control various pests and disease-spreading vectors like mosquitoes, ticks and household pests such as rats and cockroaches.
• Soil is one of the final destinations of pesticides after application.
• While utilizing the pesticides, the residues can remain in the environment for a long period and can be dispersed over a long distance.
• While spraying these chemical pesticides, a series of reactions can undergo; plants can take up pesticides through leaves and roots, the atmosphere can take up pesticides as vapors carried off as drift, pesticides can get ingested by insects, worms and microorganisms.
• The pesticides may be sorbed the particles or be leached and/or carried on the surface by the rains reaching subterranean waters and rivers.
• Environmental degradation of pesticides involves biotic transformation processes facilitated by microorganisms or plants and by abiotic processes such as chemical and photochemical reactions.
• Microorganisms present in the soil, chemical reactions and sunlight play a key role in the degradation of pesticides.
• When exposed to air or evaporate, pesticides may change into a vapor by a process called volatility.
• Once a pesticide evaporates, it is carried for miles simultaneously with the dust particles in the air.

 Therefore, only statements A and D are correct.

Concept:

Incineration:

• Incineration can be defined as the oxidation of waste materials using high temperatures.
• Incineration is also known as calcination or controlled flame combustion.
• The energy produced owing to waste treatment is used to produce electric power, making it an essential process.
• It reduces the cost of landfills.
• The two major combustible chemical elements are carbon and hydrogen.
• It is a process where the destruction of organic compounds takes place in waste treatment.
• This process is capable of destroying contaminants using high temperatures which cannot be fulfilled by any other treatments.

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

Key Points

• The principal aim of the National Forest Policy, of 1988 is to ensure environmental stability and maintenance of ecological balance including atmospheric equilibrium which is vital for the sustenance of all life forms, human, animal and plant.
• Objectives:
• Maintenance of environmental stability through preservation and, where necessary, restoration of the ecological balance that has been adversely disturbed by the serious depletion of the forests of the country.
• Conserving the natural heritage of the country by preserving the remaining natural forests with a vast variety of flora and fauna, which represent the remarkable biological diversity and genetic resources of the country.
• Checking soil erosion and denudation in the catchment areas of rivers, lakes, and reservoirs in the "interest of soil and water conservation, for mitigating floods and droughts and for the retardation of siltation of reservoirs.
• Checking the extension of sand dunes in the desert areas of Rajasthan and along the coastal tracts.
• Increasing substantially the forest/tree cover in the country through massive afforestation and social forestry programmes, especially on all denuded, degraded and unproductive lands.
• Meeting the requirements of fuel-wood, fodder, minor forest produce and small timber of the rural and tribal populations.
• Increasing the productivity of forests to meet essential national needs.
• Encouraging efficient utilisation of forest produce and maximising substitution of wood.
• Creating a massive people's movement with the involvement of women, for achieving these objectives and to minimise pressure on existing forests.
• According to the National Forest Policy, 1988, forest-based industries must not only provide employment to local people on priority but also involve them fully in raising trees and raw-material.

Therefore, statement I is correct but Statement II is false.

Concept-

• Electronic waste or e-waste is one of the emerging problems in developed and developing countries worldwide.
• It comprises a multitude of components with valuable materials, some containing toxic substances, that can have an adverse impact on human health and the environment.
• Previous studies show that India generated 0.4 million tons of e-waste in 2010 which may increase to 0.5 to 0.6 million tons by 2013–2014.
• Electronic waste or e-waste is the term used to describe old, end-of-life electronic appliances such as computers, laptops, TVs, DVD players, mobile phones, mp3 players, etc., which have been disposed of by their original users.
• Television and computer monitors normally contain hazardous materials such as lead, mercury, and cadmium, while nickel, beryllium, and zinc can often be found on circuit boards. Due to the presence of these substances, recycling and disposal of e-waste become an important issue.
• Landfilling of electronic waste is not the best operation from an environmental viewpoint.

The correct answer is: 2) A > B > D > C

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Key Points

• Greenhouse Gases (GHGs):
• These are gases that trap heat in the atmosphere, contributing to the greenhouse effect, which leads to global warming.
• The major greenhouse gases include Carbon dioxide (CO₂), Methane (CH₄), Nitrous oxide (N₂O), and Chlorofluorocarbons (CFCs).
• Each of these gases has a different impact on global warming, quantified as relative contribution (%) to global warming.
• Relative Contributions of GHGs:
• Carbon Dioxide (CO₂):
• CO₂ is the most significant greenhouse gas, contributing approximately 76% to global warming from anthropogenic sources.
• Sourced mainly from burning fossil fuels, deforestation, and various industrial processes.
• Methane (CH₄):
• CH₄ is the second most significant greenhouse gas, contributing about 16% to global warming.
• Main sources include agriculture (particularly ruminant digestion), landfills, and natural gas extraction.
• Nitrous Oxide (N₂O):
• N₂O contributes around 6% to global warming.
• Major sources include agricultural activities, industrial activities, and the burning of fossil fuels and biomass.
• Chlorofluorocarbons (CFCs):
• CFC-12 is particularly potent but contributes a smaller fraction to global warming compared to CO₂, CH₄, and N₂O.
• Despite their high global warming potential (GWP), their lower concentration leads to a relative contribution less than that of CO₂, CH₄, and N₂O.
• Used historically in refrigeration, air conditioning, and as propellants, but their use has been significantly reduced due to their role in ozone depletion.

Additional Information

• Global Warming Potential (GWP):
• GWP measures the impact of a greenhouse gas in warming the atmosphere relative to CO₂ over a specified time period (usually 100 years).
• For example, Methane has a GWP of about 25-28, meaning it is 25-28 times more potent than CO₂ over a 100-year period.
• CFC-12 has a GWP of over 10,000, making it extremely potent despite its lower concentration.
• Total Radiative Forcing:
• It is the combined effect of all the greenhouse gases in the atmosphere, influencing the Earth's energy balance.
• Radiative forcing is a measure used to compare the strength of different factors (including GHGs) in causing warming or cooling of the climate system.
• Mitigation Measures:
• Reducing fossil fuel use, increasing renewable energy sources, enhancing energy efficiency, and adopting sustainable agricultural practices.
• International agreements like the Paris Agreement aim to limit global warming by reducing GHG emissions.
• Phasing out substances like CFCs under protocols such as the Montreal Protocol to protect the ozone layer and mitigate global warming.

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

Key Points

• Radioactive liquid wastes are generated in nuclear facilities such as nuclear power plants, reprocessing facilities, research reactors and laboratories.
• They often contain not only radiotoxic isotopes but also hazardous chemicals with high reactivity, low flash or ignition points, potential risks to produce explosive materials combined with other reagents, etc.
• The chemical compositions and radioactivity levels of the generated wastes depend on the conducted operation.
• Liquid radioactive wastes possess a potential risk of human exposure during the decontamination process of radioactive waste which includes stabilization/solidification and its ultimate disposal.
• Aqueous wastes may contain short lived beta/gamma activity. They are kept in storage before disposal.
• Characteristics of reagents in the wastes and risks caused by the reagents under decontamination, solidification or disposal procedures have to be carefully investigated in advance and then an appropriate treatment process for each item preventing hazardous events has to be designed and adopted.

Therefore, both assertion and reason are correct and reason is the correct explanation of assertion.

Concept-

• Carbon dioxide ( CO₂) makes up the vast majority of greenhouse gas emissions from the sector, but smaller amounts of methane (CH₄) and Nitrous Oxide (NO₂) are also emitted.
• These gases are released during the combustion of fossil fuels, such as coal, oil, and natural gas to produce electricity.

Concept-

Solid Waste Management Rules, 2016-

• As per SWM 2016, “extended producer responsibility” (EPR) means the responsibility of any producer of packaging products such as plastic, tin, glass and corrugated boxes, etc., for environmentally sound management, till the end-of-life of the packaging products;

Plastic Waste Management Rules, 2016

• The Ministry of Environment, Forest and Climate Change has notified the Guidelines on Extended Producer's Responsibility on plastic packaging under Plastic Waste Management Rules, 2016.
• The Guidelines provide a framework to strengthen the circular economy of plastic packaging waste, promote the development of new alternatives to plastics and provide further next steps for moving towards sustainable plastic packaging by businesses.

Construction & Demolition Waste Management Rules, 2016

• Every waste generator shall segregate construction and demolition waste and deposit it at a collection center or hand it over to the authorized processing facilities
• Shall ensure that there is no littering or deposition so as to prevent obstruction to the traffic or the public or drains.

E-waste (Management) Rules, 2016

• Manufacturers, dealers, refurbished, and Producer Responsibility Organizations (PRO) have been introduced as additional stakeholders in the rules.
• A collection mechanism-based approach has been adopted to include a collection center, collection point, take-back system, etc for the collection of e-waste by Producers under Extended Producer Responsibility (EPR).

 

So the correct answer is option D.

The correct answer is Statement I is correct but Statement II is incorrect.

Key Points

Covariance:

• It measures the direction of a relationship between two variables, positive or negative correlation.
• The sign of covariance, therefore, shows the tendency for a linear relationship between the variables.
• The standard deviation is the root of variance and variance is always positive. So, the standard deviation will always be positive.
• This makes it very obvious that the product of standard deviations of two variables X and Y will always be positive.

σ = $\sqrt{\frac{\Sigma X^{2}}{N}}$

where, 

 X = x - μ (μ = mean)

 N = Total number of observations

Therefore, the statement I is correct but Statement II is incorrect.

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

Key Points

A distribution that is not symmetrical is called a skewed distribution. Such skewed distribution could be either positively skewed or negatively skewed.

1) Positively skewed distribution: It is the frequency curve of the distribution which has a longer tail towards the right side of the curve.

• In a positively skewed distribution, the values of the mean are maximum.
• The value of mode is minimum and the median lies between the two values, i.e., mean and mode.
• Mean > Median > Mode

2) Negatively skewed distribution: It is the frequency curve of the distribution which has a longer tail towards the left side of the curve.

• Here, the value of the mean is minimum and the value of the mode is maximum and the median lies in between the two.
• Mean < Median < Mode

3) Mathematical measures of skewness can be calculated by:

1. Bowley's Method: It is based on the values of median, lower and upper quartiles. The coefficient of skewness lies within the limit of ±1.
2. Karl-Pearson's Method: Where the relationship of mean and mode is established, the coefficient of skewness generally lies within +1. Where the relationship between mean and median is not established, the coefficient of skewness generally lies within +3.

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

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

Key Points

• Normal distribution is a probability distribution of random variables.
• Also called "Gaussian curve", it presents a bell shaped symmetrical curve which is continuous for continuous variables.
• In the normal curve, all distribution is symmetrical about the mean i.e., there is 'no skewness' in it.
• The mean, median and mode have the same value i.e., they coincide.
• The standard normal distribution, also called the z-distribution, is a special normal distribution where the mean is 0 and the standard deviation is 1.

Additional Information

• Any normal distribution can be standardized by converting its values into z-scores.
• Z-scores tell you how many standard deviations from the mean each value lies.
• Converting a normal distribution into a z-distribution allows you to calculate the probability of certain values occurring and to compare different data sets.

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

The correct answer is A and B only.

Key Points

Standard Error (SE):

• It is the standard deviation of the sampling distribution of a statistic.
• It's an indication of how spread out the numbers are.
• The term may also be used to refer to an estimate of that standard deviation, derived from a particular sample used to compute the estimate.

Precision:

• The property of the set of measurements of being very reproducible or of an estimate having a small random error of estimation.
• Precision is determined by standard deviation which is how much and how much and how often measurements differ from one another.
• If a standard deviation is high, then it suggests low precision.
• In other words, the precision of the sample estimate of some population parameter is the reciprocal of the standard error of the sampling distribution of the estimate.

​Types of error:

• The decision of acceptance or rejection of a null hypothesis is made on the basis of a sample from a population and hence; an element of uncertainty is always involved in making such decisions.
• Two types of errors are likely to be committed in the procedure of testing of hypothesis. These are Type-I and Type-II errors.
• Type - I error is committed when a true null hypothesis is rejected. The probability of this error is termed the level of significance of the test.
• Contrary to this, a Type-II error is committed when a false null hypothesis is accepted.

Therefore, only statements A and B are correct.

The correct answer is (A) - (IV), (B) - (III), (C) - (II), (D) - (I).

Key Points

 

 

 

 

 

 

 

 

 

 

 

Therefore, the correct answer is (A) - (IV), (B) - (III), (C) - (II), (D) - (I).

The correct answer is (A) - (III), (B) - (IV), (C) - (I), (D) - (II).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Therefore the correct answer is  (A) - (III), (B) - (IV), (C) - (I), (D) - (II).

correct option is (A) - (IV), (B) - (I), (C) - (III), (D) - (II). 

Key Points 

 

 

 

 

 

 

 

 

 

 

Hence, correct option is (A) - (IV), (B) - (I), (C) - (III), (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).

Concept-

Sedimentary rocks may be classified on the basis of grain size into three types:

Rudaceous, Arenaceous, and silt rocks.

Rudaceous (in Latin Rudous—pebbles):

• Rudaceous rocks are those rocks, which are made up of particles having a grain size of more than 2 mm in diameter.
• Rocks consist mainly of gravel, pebbles, cobbles, and boulders.
• Example- Breccia, Conglomerate.

Arenaceous (in Latin Arena—sand):

• Arenaceous rocks are those rocks, which are made up of particles having a grain size between 0.1 -2 mm diameter.
• Rocks consist mainly of sand.
• Example- sandstone

Silt rocks-

• Siltstone is a sedimentary rock composed mainly of silt-sized particles. Rocks consist mainly of silt and siltstones.
• It forms where water, wind, or ice deposit silt, and the silt is then compacted and cemented into a rock.
• Silt accumulates in sedimentary basins throughout the world.

Argillaceous-

• Argillaceous rocks are those rocks, which are made up of the finest clay particles i.e., the size of particles is less than 0.1 mm in diameter.
• Rocks consist mainly of dust, mud, and clay.
• Example- Shale

Concept:

Selective catalytic reduction:

• Selective catalytic reduction (SCR ) is a means of converting nitrogen oxides, also referred to as NO_x with the aid of a catalyst into diatomic nitrogen (N₂), and water (H₂O).
• A reductant, typically anhydrous ammonia (NH₃), aqueous ammonia (NH₄OH), or a urea (CO(NH₂)₂) solution, is added to a stream of flue or exhaust gas and is reacted onto a catalyst.
• As the reaction drives toward completion, nitrogen (N₂), and carbon dioxide (CO₂), in the case of urea use, are produced.

Electrostatic precipitator:

The gas is made to pass through a highly ionized zone where the particles get electrically charged & are separated out from the gas with the help of electrostatic forces in a powerful electric field.

• Widely used in thermal power plants, mining, iron and steel plants, etc.
• Sensitive to variable dust loadings & flow rates
• Particles collected may be wet or dry
• 99% or more efficiency can be obtained
• PM_2.5 is removed here.

Cyclone Collectors:

• Cyclone collectors are the devices through which air pollutants can be removed from the air stream with the help of vortex separation.
• It does not use filters to remove the particulates from the air stream.
• Coarse particulate matter is removed in cyclone collectors.
• The vortex separation is the method where the various gases that include the mixture of hydrogen and uranium hydro fluoride gas are injected inside the tubes and from the other tube the clean gas is separated out.
• While the electrostatic precipitator is a device that is issued to remove those particulate matters that are suspended in the air and are removed with the help of the application of the high voltage electrostatic charge that helps in collecting the dust particles on the charged plate.
• They both are devices that are used to control air pollution in the case of industries.

Scrubbers:

• Also called Venturi scrubbers and spray towers.
• Smokestacks with scrubbers
• Can remove gaseous pollutants also. Ex. SO₂,NO₂
• The particulate material can also be controlled
• Hot gases can be cooled down
• Maintenance cost is high
• A lot of waste water is produced which requires further disposal

The correct answer is (A) - (II), (B) - (III), (C) - (IV), (D) - (I).

Key Points

Absolutely stable atmosphere:

• When the ambient temperatures cool less rapidly than the saturated adiabatic lapse rate, the atmosphere is absolutely stable.
• The air wants to stay where it is.
• Environment Lapse Rate (ELR) < Dry Adiabatic Lapse Rate (DALR).

Absolutely unstable atmosphere:   

• ​If the ambient lapse rate shows cooling at a faster rate than the dry adiabatic lapse rate, the atmosphere is absolutely unstable.
• The air will always want to move to some new altitude so the vertical dispersion of pollution is enhanced.
• Environment Lapse Rate (ELR) > Dry Adiabatic Lapse Rate (DALR).

Conditional stability/instability:

• For ambient lapse rates between the dry and wet adiabatic lapse rates, the atmosphere may be stable or it may be unstable.
• We can’t tell without knowing the actual ambient temperature profile and the actual adiabatic profile.
• That region is labelled as having conditional stability.
• Saturated Adiabatic Lapse Rate < Environmental Lapse Rate < Dry Adiabatic Lapse Rate.

Dry neutral:

• ​If the ambient lapse rate is equal to the adiabatic lapse rate, moving the parcel upward or downward results in its temperature changing by the same amount as its surroundings.
• In any new position, it experiences no forces that either make it continue its motion or make it want to return to its original elevation.
• The parcel likes where it was, and it likes its new position too.
• Such an atmosphere is said to be neutrally stable.
• Environment Lapse Rate (ELR) = Dry Adiabatic Lapse Rate (DALR).

​​Therefore, the correct answer is (A) - (II), (B) - (III), (C) - (IV), (D) - (I).

The correct answer is (A) - (III), (B) - (IV), (C) - (I), (D) - (II).

Key Points

• χ2-test:
• ​The χ2-test is one of the simplest and most widely used non-parametric tests in statistical work.
• The quantity χ2-test describes the magnitude of the discrepancy between theory and observation.
• Uses of χ2-test:

1. χ2-test is used as a test of independence that is to check whether two or more attributes are associated or not.
2. χ2-test is used as a test of goodness of fit because it enables us to ascertain how appropriately the theoretical distributions such as binomial, Poisson, normal etc fit the empirical distribution.

• ​**One-Way ANOVA:**​
• ​One-Way ANOVA compares the means of two or more independent groups in order to determine whether there is statistical evidence that the associated population means are significantly different.
• One-Way ANOVA is a parametric test.
• ​​Paired t-test:
• ​A paired t-test is a statistical test that compares the averages/means and standard deviations of two related groups to determine if there is a significant difference between the two groups.
• In paired t-test, we compare the means of two groups of observations which are randomly assigned.
• ​Z-test:
• ​A z-test is used for testing the mean of a population versus a standard or testing the significance of a single mean.
• It indicates how much observation is bigger or smaller than the mean in units of standard deviation.

 Therefore, the correct answer is (A) - (III), (B) - (IV), (C) - (I), (D) - (II).

Concept-

World Ozone Day-

• World Ozone Day or International Day for Preservation of Ozone Layers is observed on September 16 every year.
• The motto behind its observation is spreading awareness among people about Ozone Layer depletion and searching for possible solutions to preserve it.

World Habitat Day-

• The United Nations has designated the first Monday of October of every year as World Habitat Day to reflect on the state of our habitats, and on the basic right of all to adequate shelter.
• The Day is intended to remind the world that we all have the power and the responsibility to shape the future of our cities and towns.

World Forest Day-

• Every year 21^st of March is celebrated as the International Day of Forests (IDF) by the United Nations (UN).
• The UN proclaimed 21st March as the IDF in 2012 to celebrate and raise awareness of the importance of all types of forests.

World water day-

• World Water Day is celebrated on 22^nd March Every Year to highlight the importance of water.
• On the Occasion of the World Water Day UN (United Nations) University’s Canadian-based Institute for Water Environment and Health (UNU-INWEH) has published an assessment report, showing the levels of water security in Africa overall are unacceptably low.

Concept-

 

Evaporation-

• Evaporation can generally be defined as a process by which a liquid is transformed into vapor.
• Evaporation is a form of vaporization that usually happens on the surface of liquids and it involves the transition of the liquid particles into the gaseous phase. Therefore, this process is said to involve a change in the phases.
• The surrounding gas must not be saturated with the substance which is evaporating.
• They transfer energy to each other as the molecules of the liquid collide, depending on how they collide with each other.
• The liquid particles will generally escape and enter the surrounding air as a gas when a molecule near the surface consumes enough energy to overcome the vapor pressure.
• The energy extracted from the vaporized liquid as evaporation occurs will decrease the temperature of the liquid, resulting in a process known as evaporative cooling.

 

So the correct option is option D.

Explanation:

• r species are characterized by smaller body sizes, rapid developmental rates, and smaller offspring.
• r-selected species thrive in disturbed habitats.
• These species have a shorter life span.
• These species adopt the r-Reproductive strategy.
• These populations are governed by their biotic potential and have the maximum reproductive capacity, .
• The production of numerous small offspring followed by exponential population growth is the defining characteristic of r-selected species.
• They require short gestation periods, mature quickly, and require little or no parental care.

Examples of r-selected species include pest organisms, such as rodents, insects, and weeds.

Population growth in r-selected species behaves according to the exponential growth equation:

$\frac{\Delta N}{\Delta t} = rN$

In this equation, N is the number of individuals in the population and t is time.

The factor (1–[N/K]) is often added to the equation to place an upper limit on population growth by accounting for environmental resistance.

Hence, option 4 is the correct answer.

Concept-

Reverse Osmosis-

• Reverse osmosis (RO) is a water purification process that uses a partially permeable membrane to separate ions, unwanted molecules, and larger particles from drinking water.
• Reverse osmosis filters have a pore size of around 0.0001 microns.
• In reverse osmosis, an applied pressure is used to overcome osmotic pressure, a colligative property that is driven by potential chemical differences of the solvent, a thermodynamic parameter.
• Reverse osmosis can remove many types of dissolved and suspended chemical species as well as biological ones (principally bacteria) from water, and is used in both industrial processes and potable water production.

Nanofiltration-

• A nanofiltration filter has a pore size of around 0.001 microns.
• Nanofiltration removes most organic molecules, nearly all viruses, most of the natural organic matter, and a range of salts. Nanofiltration removes divalent ions, which make water hard, so nanofiltration is often used to soften hard water.

Ultrafiltration-

• An ultrafiltration filter has a pore size of around 0.01 microns.
• A microfiltration filter has a pore size of around 0.1 microns, so when water undergoes microfiltration, many microorganisms are removed, but viruses remain in the water.
• Ultrafiltration would remove these larger particles, and may remove some viruses. Neither microfiltration nor ultrafiltration can remove dissolved substances unless they are first adsorbed (with activated carbon) or coagulated (with alum or iron salts).

Microfiltration-

• Microfiltration (MF) is a pressure-driven separation process, which is widely used in concentrating, purifying or separating macromolecules, colloids, and suspended particles from solution.
• MF membranes typically have nominal pore sizes on the order of 0.1–1.0 μm.
• MF processing is widely used in the food industry for applications such as wine, juice, and beer clarification, for wastewater treatment, and plasma separation from the blood for therapeutic and commercial uses.
• In biotechnology industries, MF concerns applications such as cell recycling and harvesting, separation of recombinant proteins from cell debris, and purification of process streams.

 

So the sequence of decreasing pore size is Microfiltration > Ultrafiltration > Nanofiltration > Reverse Osmosis.

Concept-

• Noise pollution is a significant problem for the quality of life in urban areas.
• Traffic noise is considered one of the important sources of noise pollution that adversely affects human health in residential urban areas.
• In most cases, the sounds and noises we hear are not steady. Apart from variations in tones, the magnitude of the sound pressure level of a sound or noise changes with time.
• The n-percent exceeded level, L_n, is the sound pressure level exceeded for n percent of the time. In other words, for n percent of the time, the fluctuating sound pressure levels are higher than the L_n level.
• L_n can be obtained by analyzing a given noise by statistical means.
• L_n, where n may be anything from 1 to 99, is that noise level exceeded for n% of the measurement time.
• By definition of percentiles, L1 must be greater than or equal to L₂, which must be greater than or equal to L3, etc.
• The commonly used value of n for the n-percent exceeded level, Ln, are 10, 50 and 90.
• L₁₀ is the level exceeded 10% of the time. For 10% of the time, the sound or noise has a sound pressure level above L10.
• For the rest of the time, the sound or noise has a sound pressure level at or below L₁₀.

Hence, increasing order in terms of noise level starting from minimum to maximum is L₉₀ < L₅₀ < L₁₀ < L₁.

Concept-

The correct sequence of steps involved in the development of a model is Identification > Formulation > Solution > validation.

• Identification- A good problem identification is always the starting point for good modeling.
• Formulation- 
• The model formulation is the step where our knowledge of a natural system is translated into mathematical form.
• It involves two steps: the construction of a conceptual model and the formulation of this conceptual model into mathematical equations.
• Solution- Finding the solution to the mathematical equations is carried out in this step.
• Validation- The verification of the solution is carried out in this step which is known as the validation of the model.

Hence, option 3 is the correct answer.

Explanation:

• Chlorophyll is a green color pigment present in the leaves of plants. It helps in the process of photosynthesis. Generally leaves contain it in a higher proportion. Therefore, R is correct.
• Chlorophyll is located in a plant’s chloroplasts, which are tiny structures in a plant’s cells. This is where photosynthesis takes place. Plants absorb most of the red and blue light that they receive as part of the process of photosynthesis.
• Some of the green light is absorbed and some are reflected off the leaves. This is the reason that plants look green.
• Chlorophyll, which cannot be detected by visible light, is sensitive to near-infrared light.
• A high percentage of near-infrared light is reflected off the leaves in healthy plants. When a plant is unhealthy, it has less chlorophyll and therefore reflects less near-infrared light. Therefore, A is correct.
• Unhealthy plants also reflect more red light. The difference between red and near-infrared light reflected off a plant is a good indicator of plant healthiness.
• Healthy vegetation absorbs blue- and red-light energy to fuel photosynthesis and create chlorophyll.
• A plant with more chlorophyll will reflect more near-infrared energy than an unhealthy plant.

​Hence, option B is the correct answer.

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

Key Points

• At tropopause, the dependence of air temperature on height is reversed.
• In other words, the temperature begins to increase with altitude.
• This type of temperature profile is called a stable profile, because rising air parcels lose buoyancy i.e., the air surrounding them is warmer than they are.
• Therefore, they tend to sink instead of rising.
• The tropopause thus acts like a "lid" for the troposphere and prevents the mixing of air across it into the next layer, the stratosphere.
• The stratosphere is also very dry because the moisture that is evaporated from the Earth's surface from oceans and land cannot rise past the lid presented by the tropopause.

Therefore, both the assertion and reason are correct and the reason is the correct explanation of the assertion.

Concept:

• Vapour pressure is defined as the pressure exerted by a vapor when it is in equilibrium with the condensed form i.e. liquid or solid form or both.
• The substance under consideration may exist in three phases under the equilibrium condition.
• The relative humidity is defined as the ratio of the partial pressure of water vapour and the equilibrium vapour pressure of water vapour multiplied by 100.

It is expressed as 

$\Phi = \frac{{{P_{{H_2}O}}}}{{P_{{H_2}O}^*}}$

Calculation:

Relative humidity = 60 %

Saturated Vapour Pressure of water = 2260 Pa

So vapour pressure of air = 0.6 × 2260 = 1356 Pa

The correct answer is OH radical.

Key points Lifetime of different chemical species in the atmosphere is:

 

 

 

 

Therefore, the chemical species with the shortest lifetime is OH radical.

Additional Information

• Hydroxyl radicals (OH) are often called the “detergent/scavenger” of the atmosphere because they control the atmosphere's capacity to cleanse itself of pollutants.
• It controls the concentrations of toxic gases like carbon monoxide and climate-relevant gases like methane.
• Its concentration in the atmosphere is very small (about 1×10⁶ molecules cm⁻³).
• OH is formed in the atmosphere when ultraviolet light (UV) from the sun strikes ozone in the presence of water vapour (H₂O). The initial reaction involves the photolysis of O₃ by solar radiation. Then the oxygen atom (O) reacts with water vapour to produce two OH radicals.

The correct answer is: CF₂ClCFCl₂

CFC-113 (Trichlorotrifluoroethane) is a chlorofluorocarbon compound widely used in refrigeration, cleaning solvents, and as a propellant before its regulation due to ozone depletion concerns. The name CFC-113 is derived from the numbering system used to identify the number of carbon, fluorine, and chlorine atoms in the molecule.

Key Points

• Composition:
• CFC-113 has the molecular formula CF₂Cl–CFCl₂.
• This means it contains 2 carbon atoms, 3 chlorine atoms, and 3 fluorine atoms.
• Numbering System for CFCs:
• The CFC number (e.g., 113) is derived from:
• First digit: Number of carbon atoms minus 1 → (2–1 = 1)
• Second digit: Number of hydrogen atoms plus 1 → (0+1 = 1)
• Third digit: Number of fluorine atoms → 3
• Structure:
• It is a halogenated hydrocarbon where chlorine and fluorine atoms are bonded to carbon atoms.
• Its structure contributes to chemical stability and long atmospheric lifetime.

Additional Information

• Uses of CFC-113:
• Formerly used as an industrial solvent for cleaning electronic components.
• Used as a refrigerant in some cooling systems.
• Environmental Impact:
• High Ozone Depletion Potential (ODP).
• Its production and use are now phased out under the Montreal Protocol.
• Alternatives:
• Hydrofluorocarbons (HFCs) and other environmentally safer refrigerants have replaced CFC-113 in most applications.

The correct answer is Prevent trans-boundary movement of hazardous waste between nations.

Key Points

• The Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal.
• It came into force in 1992 adopted in 1989
• The Convention aims to protect human health and the environment against the adverse effects of generation, transboundary movements, and management of hazardous wastes and other wastes.
• The Basel Convention regulates the transboundary movements of hazardous wastes and other wastes and obliges its Parties to ensure that such wastes are managed and disposed of in an environmentally sound manner.
• It is the most comprehensive global environmental agreement on hazardous wastes and other wastes.
• With 175 Parties, it has nearly universal membership.
• The Convention covers toxic, poisonous, explosive, corrosive, flammable, ecotoxic, and infectious wastes.
• Parties are also obligated to minimize the quantities transported, to treat and dispose of wastes as close as possible to their place of generation and to prevent or reduce the generation of wastes at source.

Therefore, the Basel convention (1989) was designed to prevent the transboundary movement of hazardous waste between nations.

The correct answer is Metaphire posthuma.

Key Points

• Epigeic earthworms live in areas containing high amounts of organic matter.
• They live at or near the soil surface and feed on leaf litter, decaying plant roots or dung.
• These earthworms do not form permanent burrows.
• Epigeic species tend to have dark skin colour (pigmentation).
• Epigeic species tend to be small (1 – 18 cm) in length.

Examples of Epigeic earthworms:

• Dendrobaena veneta
• Dendrobaena hortensis
• Dendrobaena octaedra
• Eisenia fetida
• Eisenia andrei
• Dendrodrilus rubidus
• Eiseniella tetraedra
• Eudrilus eugeniae
• Allolobophoridella eiseni

​Metaphire posthuma is an endogeic geophagous earthworm.

Therefore, the correct answer is Metaphire posthuma.

Concept-

Pyrolysis-

• Pyrolysis is one of the technologies available to convert biomass to an intermediate liquid product that can be refined to drop-in hydrocarbon biofuels, oxygenated fuel additives, and petrochemical replacements.
• Pyrolysis is the heating of organic material, such as biomass, in the absence of oxygen.
• Biomass pyrolysis is usually conducted at or above 500 °C, providing enough heat to deconstruct the strong bio-polymers mentioned above.
• Because no oxygen is present combustion does not occur, rather the biomass thermally decomposes into combustible gases and bio-char.
• Most of these combustible gases can be condensed into a combustible liquid, called pyrolysis oil (bio-oil), though there are some permanent gases (CO­₂, CO, H₂, light hydrocarbons).

Slow pyrolysis-

• Slow pyrolysis is the slow heating of organic material in absence of oxygen. Instead of combusting, the volatiles from the organic material evaporates partly, and a product (charcoal) remains, consisting of a large part (normally 80%) of carbon.
• Slow pyrolysis is also called carbonization, and emphasizes the solid charcoal as the main product, instead of fast pyrolysis which emphasizes the liquid product.
• Biochar is the main product of the slow pyrolysis of biomass.

The correct answer is: "CH₄ and CO₂"

Key Points

• Process of Anaerobic Digestion:
• Anaerobic digestion is a biological process by which microorganisms break down organic matter in the absence of oxygen.
• It is widely used in managing municipal solid waste (MSW), sewage sludge, and agricultural residues.
• Stages of Anaerobic Digestion:
• Hydrolysis: Complex organic polymers like carbohydrates, fats, and proteins are broken into simple sugars, fatty acids, and amino acids.
• Acidogenesis: These simple compounds are converted to volatile fatty acids (VFAs), CO₂, and hydrogen (H₂).
• Acetogenesis: VFAs are further converted into acetic acid, CO₂, and H₂.
• Methanogenesis: Finally, methanogenic archaea convert acetic acid and CO₂/H₂ into methane (CH₄) and carbon dioxide (CO₂).
• Dominant Gaseous Products:
• The final gas mixture, commonly known as biogas, mainly contains:
• Methane (CH₄): ~50–70%
• Carbon dioxide (CO₂): ~30–50%
• These two are the dominant products, especially from municipal waste rich in organic matter.

Additional Information

• CO₂ and H₂:
• These gases are intermediate products formed during acidogenesis and acetogenesis.
• Hydrogen is not a major end-product, as it is consumed during methanogenesis to reduce CO₂ into CH₄.
• CH₄, CO₂, and H₂:
• Although all three can be present, H₂ occurs in small, transient amounts, not as a dominant component.
• Only CH₄ and CO₂ are dominant and stable in the biogas output.
• O₂ and H₂S:
• Oxygen is absent in anaerobic processes by definition.
• Hydrogen sulfide (H₂S) may be present in trace amounts due to degradation of sulfur-containing compounds, but it is not a dominant product.

The correct answer is All of the above.

Key Points

The following four categories of ecotechnology may serve as the foundation for ecological engineering:

1. Ecosystems are used to reduce or solve a pollution problem that otherwise would be (more) harmful to other ecosystems. A typical example is the use of wetlands for wastewater treatment.
2. Ecosystems are imitated or copied to reduce or solve a pollution problem, leading to constructed ecosystems. Examples are fishponds and constructed wetlands for treating wastewater or diffuse pollution sources.
3. The recovery of ecosystems after significant disturbances. Examples are coal mine reclamation and restoration of lakes and rivers.
4. The use of ecosystems for the benefit of humanity without destroying the ecological balance (i.e., the utilization of ecosystems on an ecologically sound basis). Typical examples are the use of integrated agriculture and the development of organic agriculture; this type of ecotechnology finds wide application in the ecological management of renewable resources.

Since all statements regarding ecotechnology are correct. Therefore, the correct option should have been all of the above only.

The correct answer is 30 Years.

Key Points

Validity of environmental clearance (EC):

• River valley projects - 10 years
• Mining - 30 years
• Other projects/activities - 5 years

The period of validity may be extended by the regulatory authority concerned by a maximum period of five years.

Therefore the correct answer is 30 years.

Additional Information

• The EIA Notification of 1994 made environmental clearance (EC) mandatory for all new projects and expansion/modernisation of existing projects covering 29 disciplines (later increased to 32 ) which included hydro-power, major irrigation and flood control projects.
• The following projects or activities require prior environmental clearance from the concerned regulatory authority:
• ​All new projects or activities, and
• Expansion and modernization of existing projects or activities with the addition of capacity beyond the limits specified for the concerned sector, that is, projects or activities which cross the threshold limits, after expansion or modernization.
• All projects or activities included as Category ‘A’ require prior environmental clearance from the Ministry of Environment and Forests (MoEF) on the recommendations of an Expert Appraisal Committee (EAC) to be constituted by the Central Government.
• All projects or activities included as Category ‘B’ require prior environmental clearance from the State Environment Impact Assessment Authority (SEIAA). The SEIAA shall base its decision on the recommendations of a State Expert Appraisal Committee (SEAC).
• The environmental clearance process for new projects comprises a maximum of four stages:
• Stage (1) Screening
• Stage (2) Scoping
• Stage (3) Public Consultation
• Stage (4) Appraisal

The correct answer is Public Liability Insurance Act.

Key Points

• The Environment Relief Fund (ERF) was established under the Public Liability Act, 1991 (PLIA), to provide immediate relief to victims of accidents involving hazardous substances.
• It falls under Section 7A of the Public Liability Act, of 1991.
• ERF consists of compensation awarded by the National Green Tribunal (NGT) for damage to the environment under Section 24 of the NGT Act, 2010.

​Therefore, the correct answer is Public Liability Act.

Additional Information

• The Environment (Protection) Act was enacted in 1986 with the objective of providing for the protection and improvement of the environment. 
• It empowers the Central Government to establish authorities charged with the mandate of preventing environmental pollution in all its forms and tackling specific environmental problems that are peculiar to different parts of the country.
• The Act was last amended in 1991.
• The Forest (Conservation) Act of 1980 is an act by the Parliament of India which ensures the conservation of forests and their resources.​
• The Act restricts the state government and other authorities from taking decisions first without permission from the central government.
• This Act also provides penalties for the infringement of the provisions of this Act.
• The Wild Life (Protection) Act, 1972 is an Act of the Parliament of India enacted for the protection of plants and animal species.
• The Act provides for the formation of wildlife advisory boards, and wildlife wardens specify their powers and duties, etc.
• It helped India become a party to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
• Its provisions paved the way for the formation of the Central Zoo Authority.
• The Act created six schedules which gave varying degrees of protection to classes of flora and fauna.

The correct answer is Category 'B2' projects.

Key Points

• According to the EIA notification 2006, all projects and activities are broadly categorized into two categories - Category A and Category B.
• All projects or activities included as Category ‘A’ require prior environmental clearance from the Central Government in the Ministry of Environment and Forests (MoEF) on the recommendations of an Expert Appraisal Committee (EAC) to be constituted by the Central Government.
• All projects or activities included as Category ‘B’ require prior environmental clearance from the State/Union Territory Environment Impact Assessment Authority (SEIAA).
• The projects requiring an Environmental Impact Assessment report shall be termed Category ‘B1’.
• The projects which do not require an Environmental Impact Assessment report shall be termed Category ‘B2’.

Therefore, the correct answer is Category ‘B2’.

The correct answer is A, B, and C only.

Key Points

• Probability of Poisson distribution:

​

Hence, Mean = 2

• In the case of Poison distribution of this type,

          μ = variance

Therefore, variance = 2

• By solving P(x=1) = P(x=2), we concluded μ = 2.
• Applying this value in the below equation.

​

 

The answer is e^-2.

Therefore, only A, B, and C are correct.

Explanation

• Climate change refers to the variability in the average weather conditions that are measured for a long period or decades.
• Many consequences are there due to this climate change.
• According to Inter-governmental Panel on Climate Change (IPCC), there are some countries that are resilient but not immune to climate change.
• The top countries ranked by resilience to climate change include Norway, New Zealand, Finland, Denmark, and Sweden. Therefore, A is false.
• These countries are resilient to climate change because of the measures taken to tackle the effects including green buildings, reduced use of fossil fuels, use of renewable energy, etc.
• Nearly, 46 least-developed countries (LDCs) which have just 14% of the world population have higher contributions to CO₂ emissions.
• But, there are some countries, which contribute less than 1% of carbon-dioxide emissions
• Recently held Conference of Parties, COP-26 referred that three of the world’s smallest nations – Bhutan, Suriname, and Panama – stood out from the rest by showing that they absorb more greenhouse gas than they emit.
• This is mainly by the carbon-negative actions taken throughout the nations. Therefore, R is true.

​Hence, option 4 is the correct answer.

Explanation:

• The standard solar panel size, the 60-cell is structured as a 6×10 grid and measures 3.25 feet by 5.5 feet.
• The average 72-cell solar panel size measures 3.25 feet by 6.42 feet and is laid out as a 6 x 12 grid, making them almost a foot taller than the 60-cell standard-size panels.
• The average rotor diameter in 2021 was 127.5 meters (418 feet)—longer than a football field.
• Larger rotor diameters allow wind turbines to sweep more area, capture more wind, and produce more electricity.

Therefore, A is true.

• The energy per unit area per unit time passing through a plane perpendicular to the wave, called the energy flux and denoted by S, can be calculated by dividing the energy by the area A and the time interval Δ t.
• Low energy flux density is the shared characteristic of almost all renewable energy sources. Therefore, B is true.
• The mean and 90-percentile power densities for wind are 0.50 and 0.80 We m−2, while the corresponding values for solar are 5.4 and 7.1 We m−2.

​Hence, option 1 is the correct answer.

The correct option is 'Both (A) and (R) are true and (R) is the correct explanation of (A)'.

Key Points

• Assertion A: Hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) are used as substitute compounds for chlorofluorocarbons (CFCs).
• This statement is true.
• Environmental Concerns: CFCs were widely used in refrigeration, air conditioning, foam production, and as propellants in aerosol sprays. However, they were found to be major contributors to ozone layer depletion, prompting the search for safer alternatives.
• International Agreements: The Montreal Protocol, an international treaty adopted in 1987, aimed to phase out the production and consumption of ozone-depleting substances, including CFCs. HFCs and HCFCs were introduced as less harmful alternatives.
• Reason R: HCFCs and HFCs are quite susceptible to reaction with OH radicals in the troposphere.
• This statement is true.
• Atmospheric Chemistry: Hydroxyl (OH) radicals are highly reactive molecules that play a crucial role in the chemical transformation of pollutants in the atmosphere. They help to break down various compounds, including HCFCs and HFCs.
• Decomposition Process: When HCFCs and HFCs are emitted into the atmosphere, they undergo reactions with OH radicals in the troposphere. This significantly reduces their atmospheric lifetime compared to CFCs, which are less susceptible to such reactions and can persist longer, reaching the stratosphere and causing more harm to the ozone layer.
• Evaluation of the Relationship Between A and R:
• Both the assertion and the reason are accurate and interlinked.
• The reason explains why HFCs and HCFCs are preferred over CFCs. Their susceptibility to reacting with OH radicals means they degrade faster in the troposphere. This reduces the likelihood of them reaching the stratosphere and causing significant ozone depletion, thus making them better alternatives.
• Therefore, the reason (R) directly supports and provides a correct explanation for the assertion (A).

Additional Information

• Environmental Impact: The introduction of HFCs and HCFCs was largely driven by environmental needs. CFCs were recognized as primary culprits in creating the ozone hole over Antarctica, which led to stringent regulations and the search for safer alternatives.
• Montreal Protocol: This treaty has been one of the most successful international environmental agreements. It has led to the significant reduction in the use of ozone-depleting substances, contributing to the gradual recovery of the ozone layer.
• OH Radicals: Hydroxyl radicals are often referred to as the "detergent" of the atmosphere due to their role in decomposing a wide range of atmospheric pollutants. Their reaction with HCFCs and HFCs makes these substitutes shorter-lived in the lower atmosphere.

Explanation:

• Regression analysis is a set of statistical methods used for the estimation of relationships between a dependent variable and one or more independent variables. Therefore, A is true.
• It can be utilized to assess the strength of the relationship between variables and for modeling the future relationship between them.
• Regression analysis includes several variations, such as linear, multiple linear, and nonlinear. The most common models are simple linear and multiple linear.
• Nonlinear regression analysis is commonly used for more complicated data sets in which the dependent and independent variables show a nonlinear relationship. This includes a curvilinear relationship between the variables. Therefore, R is false.

Hence, option 3 is the correct answer.

Additional Information:

Simple Linear Regression

Simple linear regression is a model that assesses the relationship between a dependent variable and an independent variable. The simple linear model is expressed using the following equation:

Y = a + bX + ϵ

Where:

• Y – Dependent variable
• X – Independent (explanatory) variable
• a – Intercept
• b – Slope
• ϵ – Residual (error)

The correct answer is Aerobic fermentation.

Key Points

• Take a look at the sixth sentence of the passage:
• ​Vinegar was originally produced by leaving wine in shallow bowls or partially filled barrels where it was slowly oxidized to vinegar by the development of natural flora.
• ​Thus, it can be concluded that vinegar is produced by the oxidation of wine which is carried out in the presence of oxygen. The whole process is called aerobic fermentation.

​​Therefore, the correct answer is aerobic fermentation.

The correct answer is Mixed culture of yeasts.

Key Points

• Examine the fifth sentence of the passage:
• ​However, many traditional ale-producing breweries still use mixed yeast cultures.

​Therefore, the correct answer is mixed yeast cultures.

The correct answer is Hansen.

Key Points

• Consider the fourth sentence of the passage:
• ​Hansen started his pioneering work by isolating and propagating single yeast cells to produce pure culture.

​​Therefore, the correct answer is Hansen.

The correct answer is Wooden.

Key Points

• Take a look at the second sentence of the passage:
• However, the first true large-scale breweries date from the 1700s AD when wooden vats of 1500 barrels capacity were introduced.

​​​Therefore, the correct answer is wooden.​

The correct answer is Alcohol.

Key Points

• Analyze the first sentence of the passage:
• ​The fermentation products prior to 1900 AD were confined to potable alcohol and vinegar.
• ​Analyze the last sentence of the passage:
• ​Between the years, 1900 AD and 1940 AD, the most important advances were the development of the baker's yeast, solvent fermentation, citric acid production and lactic acid production.
• ​When we analyse these two sentences and the passage as a whole, it can be concluded that the oldest product of fermentation technology has been the production of alcohol. It was after 1900 AD that the development of other products of fermentation like baker's yeast, citric acid and lactic acid started taking place.

​Therefore, the correct answer is alcohol.

Concepts:

• Humic acids (HA) are organic molecules that play essential roles in improving soil properties, plant growth, and agronomic parameters.
• The sources of HA include coal, lignite, soils, and organic materials.
• Humic acid-based products have been used in crop production in recent years to ensure the sustainability of agriculture production.
• HA can positively affect soil physical, chemical, and biological characteristics, including texture, structure, water holding capacity, cation exchange capacity, pH, soil carbon, enzymes, nitrogen cycling, and nutrient availability.
• Humic substances are complex, heterogeneous molecules that are operationally defined on the basis of solubility fulvic acid is completely soluble in aqueous solution whereas humic acid is “soluble” in alkali but precipitates in acid solutions.

Concept:

Toxicity of Mercury:

• The toxic effects of mercury depend on its chemical form and the route of exposure.
• Methylmercury [CH₃Hg] is the most toxic form.
• The most toxic form of mercury in water is H3C - Hg+
• It affects the immune system, alters genetic and enzyme systems, and damages the nervous system, including coordination and the senses of touch, taste, and sight.
• Methylmercury is particularly damaging to developing embryos, which are five to ten times more sensitive than adults.
• Exposure to methylmercury is usually by ingestion, and it is absorbed more readily and excreted more slowly than other forms of mercury.
• Elemental mercury, (Hg), the form released from broken thermometers, causes tremors, gingivitis, and excitability when vapors are inhaled over a long period of time.
• Although it is less toxic than methylmercury, elemental mercury may be found in higher concentrations in environments such as gold mine sites, where it has been used to extract gold.
• If elemental mercury is ingested, it is absorbed relatively slowly and may pass through the digestive system without causing damage.
• Ingestion of other common forms of mercury, such as the salt HgCl₂, which damages the gastrointestinal tract and causes kidney failure, is unlikely from environmental sources.

Concept-

Dobson unit-

• The Dobson Unit is the most common unit for measuring ozone concentration.
• One Dobson Unit is the number of molecules of ozone that would be required to create a layer of pure ozone 0.01 millimeters (One-hundredth of a millimeter) thick at a temperature of 0 degrees Celsius and a pressure of 1 atmosphere (the air pressure at the surface of the Earth).
• Expressed another way, a column of air with an ozone concentration of 1 Dobson Unit would contain about 2.69x10¹⁶ ozone molecules for every square centimeter of an area at the base of the column.
• Over the Earth’s surface, the ozone layer’s average thickness is about 300 Dobson Units or a layer that is 3 millimeters thick.

Important Points

• The Richter magnitude scale was developed in 1935 by Charles F. Richter of the California Institute of Technology as a mathematical device to compare the magnitudes of earthquakes.
• The decibel (abbreviated dB) is the unit used to represent the intensity of sound.

The correct answer is Carbon dioxide.

Key Points

The components of volcanic gases are water vapour (H₂O), carbon dioxide (CO₂), sulfur either as sulfur dioxide (SO₂) hydrogen sulfide (H₂S), nitrogen, argon, helium, neon, methane, carbon monoxide, and hydrogen.

The proportion of different gases in volcanic eruption are:

• Water vapour — 50 - 90%
• Carbon dioxide — 1 - 40%
• Sulphur dioxide — 1 - 25%
• Hydrogen sulfide — 1 - 10%
• Hydrogen chloride — 1 - 10%
• Other gases found in lower amounts include carbon disulfide, carbonyl sulfide, and hydrogen fluoride.

Therefore, after water vapour (steam), carbon dioxide is the next abundant gas in a volcanic eruption.

Calculation:

Given:

Saturation current = 60 nAm^-2

Solar radiation-induced current = 600 Am

Temperature = 27°C

As we know that Open-circuit current, 

Voc  =  $\frac{k_BT}{q}ln {(J_{ph}) \ {} \over (J_o)}$

V_oc = open-circuit voltage of the solar cell

$\frac{k_BT}{q}$= thermal voltage (25.85 mV at 300 K)

J_ph = solar radiation-induced current

J_o = minority saturation current or dark current

Voc  = $\frac{k_BT}{q}ln {(J_{ph}) \ {} \over (J_o)}$

Voc = 0.2585 $ln {(600) \ {} \over (60)}$

Voc = 0.2585 $ln = (10)$

Voc = 0.2585 × 2.3025 = 0.5951 = ~0.6 V

Therefore, V_oc = ~0.6 V

The correct answer is Paraboloid dish collector.

Key Points

• A solar parabolic dish is a type of solar collector that uses a parabolic reflector to focus sunlight onto a central receiver, where the solar energy is absorbed and converted into heat.
• It accomplishes this through the use of a computer and dual-axis tracking.
• Within CSP technologies, parabolic dish concentrators are the most efficient of all solar collector types due to a combination of dual-axis tracking and a high concentration ratio.
• The dishes are laid out on a solar field with spacing to minimize collisions and shading of the collector while allowing sufficient access for maintenance and minimizing the pipework and parasitic pumping energy for the heat transfer fluid.
• The operating temperature of the system is over 1800 K while the concentration ratio is in the range between 1000 and 5000 K.

Therefore, the solar collector that has the highest concentration ratio is a paraboloid dish collector.

Additional Information

• A compound parabolic collector with a plane receiver has a concentration ratio of 1.7.
• Fresnel lens collector has a concentration ratio of 1500.
• The cylindrical parabolic collector has a concentration ratio of 20.

Explanation:

• Frequency weightings are used to measure and report noise levels in a sound level meter or noise dosimeter.
• The most used frequency weightings are A, C, and Z.
• ‘A’ Frequency Weighting - This is the standard weighting of the audible frequencies and reflects the response of the human ear to noise. The frequency of 1000 Hz has the least correction.
• ‘C’ Frequency weighting - Used for the measurement of Peak Sound Pressure level.
• ‘Z’ Frequency weighting - It is a flat frequency response between 10 Hz and 20 kHz ±1.5 dB excluding microphone response.