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

Total Questions: 99

81. Which of the following key term is NOT included in the definition of Disaster in the Disaster Management Act of 2005?

Correct Answer: 4. Risk
Solution:

Disaster (DMA, 2005): Defined as a catastrophe, mishap, calamity or grave occurrence arising from natural/man-made causes leading to substantial loss/damage beyond coping capacity.

Included terms: Catastrophe, Mishap, Calamity (and "grave occurrence").

Not included: Risk is not part of the definitional key terms.

82. Match the LIST-I with LIST-II.

Choose the correct answer from the options given below:

Correct Answer: 4. A-IV, B-III, C-II, D-I
Solution:

A. NDBal (Bareness) → IV: (SWIR - TIR)/ (SWIR + TIR) - bare land enhances SWIR vs thermal band.

B. NDBI (Built-up) → III (per options): (Canonical NDBI is (SWIR - NIR)/(SWIR + NIR); within given choices, III is the placeholder provided.)

C. NDWI (Moisture) → II: (NIR - SWIR)/(NIR + SWIR) - Gao's NDWI for vegetation water content.

D. NDSI (Snow) → I: (Green - SWIR)/(Green + SWIR) snow bright in green, dark in SWIR.

83. Average solar radiation incident at the top of Earth's atmosphere is 342 Wm⁻². The global planetary albedo is 0.30, and 67 Wm⁻² of incident radiation is absorbed by atmosphere. On an average, 390 Wm⁻² is lost from the Earth's surface as IR, but the Earth absorbed 80% of the form of IR emitted downward by the atmosphere. If the global average sensible heat flux away from the surface is 24 Wm⁻². Calculate the global latent heat flux.

Correct Answer: 2. ~70 Wm⁻²
Solution:

Surface energy balance (steady state):

Interpretation: With the stated 80% absorption of downward IR and given fluxes, the global latent heat flux= 70 W m⁻².

84. Which of the following is not among the four stages of risk assessment?

Correct Answer: 4. Risk management
Solution:

Four stages of risk assessment: Hazard identification, Dose-response assessment, Exposure assessment, Risk characterization. Risk management is separate (policy/control decision phase), not a stage within risk assessment.

85. Consider the following statements and choose the CORRECT statements about organic compounds (OCs).

A. The OCs are usually combustible and less soluble in water.
B. Several OCs exist for a given formula.
C. Reaction of OCs are usually ionic than molecular.
D. The OCs can be derived from nature, by synthesis, by fermentation.
E. Saturated hydrocarbons (Paraffins) are quite inert towards most chemical reagents.
Choose the correct answer from the options given below: 

Correct Answer: 4. A, B, D and E only
Solution:

A. True: Most organics are combustible and often poorly water-soluble (hydrophobic moieties).

B. True: Isomerism → several OCs can share a single formula.

C. False: Organic reactions are predominantly molecular/covalent mechanisms (polar, radical, pericyclic); not "usually ionic rather than molecular."

D. True: Organics arise from natural sources, synthetic routes, and fermentation.

E. True: Paraffins (saturated hydrocarbons) are relatively inert toward many reagents (lack functional groups).

86. A toxic substance is present at 10 mg/l (=10 ppm) level in water. Arrange the following subjects (A, B, C, D and E) in decreasing order of their daily dose in (mg kg⁻¹ day⁻¹) of this substance.

A. Subject taking 2 liters of water per day and have body weight of 50 kg.
B. Subject taking 2 liters of water per day and have body weight of 70 kg.
C. Subject taking 1 liter of water per day and have body weight of 10 kg.
D. Subject taking 5 liters of water per day and have body weight of 100 kg.
E. Subject taking 1 liter of water per day and have body weight of 70 kg.
Choose the correct answer from the options given below:

Correct Answer: 2. C, D, A, B, E
Solution:



Reasoning: Higher intake and lower body mass increase dose.
Decreasing order: C > D >A > B > E.

87. Electric power generated from an ideal wind turbines is ________ .

Correct Answer: 2. proportional to cube of wind velocity
Solution:

88. Match the LIST-I with LIST-II.

LIST-I (Coal Lithotypes)LIST-II (Composition)
A. VitaminI. Mainly inertinite and exinite macerals
B. Cannel coalII. Mainly fusinite
C. DurainIII. Vitrinite macerals with <20% exinite macerals
D. FusainIV. Dominated by alginite

Choose the correct answer from the options given below:

Correct Answer: 3. A-III, B-IV, C-I, D-II
Solution:

A. Vitrain → III: Bright, banded lithotype dominated by vitrinite from woody tissues; typically <20% exinite (liptinite).

B. Cannel coal→IV: A sapropelic coal, fine-grained, rich in alginite/liptinite (algae/ spores); hydrogen-rich, dull luster.

C. Durain →I: Dull, hard bands with appreciable inertinite and exinite macerals; more mineral matter.

D. Fusain → II: Charcoal-like, silky black; dominated by fusinite (oxidized/charred plant material). Takeaway: Mapping relies on dominant macerals (vitrinite, liptinite/exinite, inertinite/fusinite) characteristic of each lithotype.

89. In a fertile pond (water body), the region where the light intensity is usually too low for photosynthesis and only community respiration occurs. The area where respiration (R) is greater than primary production (P), i.e. P/R < 1, is called as

Correct Answer: 2. profundal zone
Solution:

Definition: The profundal is the deep, open-water region below the compensation depth; light is insufficient for net photosynthesis.

Metabolism balance: Community respiration (R) exceeds primary production (P) → P/R < 1. Energy supply depends on settling detritus from upper zones.
Contrast:

• Littoral: nearshore, light to the bottom, macrophytes abundant.
• Limnetic/pelagic: open surface waters with active photosynthesis (P/R ≥ 1) above the compensation depth.

90. Arrange the following stages of coal development from lower to higher grade.

A. Dehydration
B. Peatification
C. Bituminization
D. Debituminization
E. Graphitization
Choose the correct answer from the options given below:

Correct Answer: 2. B, A, C, D, E
Solution:

В. РPeatification (lowest rank): Biochemical alteration of plant debris → peat; high moisture, high O/C and H/C, low carbon ordering.

A. Dehydration: Burial/compaction and devolatilization reduce moisture and oxygen, moving toward lignite/sub-bituminous ranks.

C. Bituminization: Increased thermal maturation yields bituminous coal; volatile bitumens prominent; vitrinite reflectance rises.

D. Debituminization: Further metamorphism drives off volatiles, increases aromatic ordering→ anthracite/meta-anthracite; fixed carbon high.

E. Graphitization (highest): At extreme metamorphic conditions, carbon structure approaches graphite (crystalline ordering).

Overall trends (low → high rank): Carbon content ↑, volatiles/moisture ↓, H/C & O/C ↓, energy density & reflectance ↑.