UGC NTA NET/JRF Exam, Environmental Sciences, June-2025

D.Thickening → first: Raw sludge is very dilute (≈0.5-2% solids). Gravity/thickening reduces volume early to lower sizing/energy needs downstream.

A. Stabilization → second: Anaerobic/aerobic digestion (or lime stabilization) reduces volatile solids, pathogens, odors, and biogas may be produced. Stabilizing before mechanical handling improves safety and dewatering behavior.

C. Conditioning → third: Chemical (polymers, ferric, lime) or thermal conditioning added immediately before dewatering to improve floc structure, drainage, and cake solids.

B. Dewatering → fourth: Centrifuges, belt presses, filter presses remove free/interstitial water to produce a stackable "cake" (typically 15-35% TS depending on process).

E. Reduction → last: Further volume/ mass reduction and final treatment (e.g., drying beds, thermal drying, composting, incineration) or beneficial use/disposal.

А. Воx-plot gives 55th percentile: Incorrect. Standard box-plots display median (50th), Q1 (25th), Q3 (75th), whiskers, and outliers; they do not yield the 55th percentile exactly.

B. Chernoff plot is hierarchical: Incorrect. Chernoff faces encode multivariate variables as facial features; they are not a hierarchical chart.

C. Pie-chart: area of circle non-proportional to frequency: Incorrect/misleading. In pie charts, a category's sector (angle/area) is proportional to its frequency; the claim as stated is not correct for how values are represented.

D. Ishikawa for cause-effect: Correct. Ishikawa/ fishbone diagrams visualize cause-effect relationships.

E. Histogram for categorical data: Incorrect. Histograms are for continuous (binned) numerical data; bar charts suit categorical data.

Net: Only D is correct, but no option contains D only ⇒ NONE.

To delegate simpler projects to state authorities and complex ones to the central government.

Rationale in EIA 2006: Projects are categorized by scale and potential environmental impact.

Category A: Appraised at Central (MoEFCC/ EAC) due to larger scale/significant impacts, mandatory EIA and often public hearing.

Category B: Handled by State (SEIAA/ SEAC); B1 typically requires EIA, B2 may be exempt from full EIA.

This structure allocates appraisal to the appropriate level and streamlines the process while maintaining rigor for higher-impact projects.

A. Article 51A(g) → II: Fundamental Duty "to protect and improve the natural environment (forests, lakes, rivers, wildlife) and to have compassion for living creatures."

B. Article 49 → I: Protection of monuments and places and objects of national importance.

C. Article 48 → IV: Organization of agriculture and animal husbandry on modern/scientific lines (incl. breed improvement, cow protection).

D. Article 48A → III: Protection and improvement of environment and safeguarding of forests and wildlife (42nd Amendment, 1976).

Mapping: 51A(g)-II; 49-I; 48-IV; 48A-III ⇒ A-II, B-I, C-IV, D-III.

Concept: Production efficiency = fraction of assimilated energy converted to new consumer biomass. It rises with food quality and lower metabolic overhead; ectotherms generally exceed endotherms.

D. Detritivores lowest: Detritus is lowquality, refractory (high lignin/cellulose), with microbial defenses; even after assimilation, a larger share goes to maintenance, so lower production efficiency.

A. Fishes → next: Ectothermic and buoyant (favorable vs. terrestrial vertebrates) but as vertebrates they still have higher maintenance costs than many invertebrates; moderate production efficiency.

C. Herbivores → higher: Many ectothermic herbivores (e.g., insects) can achieve high conversion of assimilates due to efficient growth strategies.

B. Carnivores → highest: Protein-rich, easily digestible prey yields high assimilation; with ectothermic metabolism, a greater fraction of assimilates is converted to biomass.

Order (increasing): Detritivores < Fishes < Herbivores < Carnivores = D, A, С, В.

Statement 2 is incorrect. Ground-level ozone (O₃) production depends on NO₂ photolysis and VOC radicals. Where NO is high, it titrates ozone via NO + O₃→ NO₂ + O₂, thereby reducing O₃ even if NOx is abundant.

1 (Correct): Diesel engines operate lean; the globally cooler, oxygen-rich bulk mix can yield lower thermal NO formation compared with stoichiometric gasoline flame cores (engine-out NO chemistry is nuanced, but the lean regime tends to suppress peak NO in bulk).

3 (Correct): London (1952) smog was a sulfurous/reducing smog driven by SO₂ and smoke; ozone was not the dominant oxidant species.

4 (Correct): Aldehydes (carbonyls) have n → π* bands in near-UV; they absorb strongly in UV-B (<315 nm) with weak tails into short-wavelength UV-A for several species.

С. Maharashtra: In Swachh Survekshan 2023, Maharashtra ranked as the best-performing state in cleanliness among large states. Its strong solid waste management systems, decentralized waste segregation, and largescale citizen participation initiatives pushed it to the top.

B. Madhya Pradesh: Secured the second position. Cities like Indore (ranked India's cleanest city for the 7th consecutive year) contributed heavily to this ranking.

A. Chhattisgarh: Took the third place. It has consistently been among the top states due to strong community-level waste segregation and urban cleanliness drives.

D. Odisha: Ranked lower than the above three, but still ahead of Telangana due to improvements in waste processing facilities.

E. Telangana: Placed the lowest among the listed states, reflecting ongoing challenges in scaling up urban sanitation infrastructure.

Order (Top → Bottom): Maharashtra → Madhya Pradesh → Chhattisgarh → Odisha → Telangana.

Colonizing species face less competition for resources in secondary succession compared to primary succession:

Primary succession: Begins on new, barren substrates (e.g., bare rock, lava, sand dunes). Colonizers (lichens, mosses) face harsh abiotic stress like no soil, limited water/nutrients, temperature extremes. However, because very few organisms are present, competition is initially low.

Secondary succession: Occurs after disturbance (e.g., fire, flood, agriculture). Since soil, seed banks, roots, and microbes remain, many species can re-colonize quickly.

This results in higher initial competition among species for nutrients, light, and space.

Thus, statement 4 is incorrect, because competition is generally stronger in secondary succession than in primary succession.

A. Sound power (W) = Intensity (I) Area (A): Correct. Power is the total sound energy per second crossing a surface area at a given intensity.

B. Sound period (T) and frequency (f) are inversely related: Correct since T = 1/f.

C. Speed of sound formula given (C = 20.05 × Temp²): Incorrect. The speed of sound is proportional to the square root of absolute temperature, not quadratic. Correct relation: c= √YRT or approximately c = 331 + 0.6T(°C).

D. L = 10 log₁₀(Q/Q₀): Correct formula for expressing sound levels (e.g., power level, intensity level) in decibels relative to a reference.

E. I = P²ms /(pc): Correct relation connecting sound intensity with root-mean-square acoustic pressure in a plane progressive wave.
Hence, the valid set is A, B, D, E.

The aerodynamic diameter (d) represents the size of a unit-density sphere (1 g/cm³) with the same settling velocity as the particle.
Formula:
Rounded to one decimal: ≈ 3.5 µm.
Thus, the aerodynamic diameter of the given particle is about 3.5 µm.