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

As per the Construction and Demolition Waste Management Rules, 2016, issued under the Environment (Protection) Act:

• Waste generators producing ≥300 tons/month/ project must:
• Segregate the waste into concrete, soil, steel, wood, etc.
• Submit a waste management plan to the local authority for approval.
• Ensure that the plan includes storage, transport, and disposal provisions.

This rule is applicable to large-scale construction and demolition projects generating substantial waste.

In a biosensor, the component responsible for detecting the target analyte is the recognition element (also called bioreceptor). This may include:
• Enzymes
• Antibodies
• Nucleic acids
• Whole cells, including bacterial cells

Whole bacterial cells act as biological recognition elements because they respond to specific analytes (e.g., pollutants, nutrients) and generate a measurable signal via metabolism or binding. Thus, bacterial cells are part of the recognition element.

Typical elemental composition of humic substances (by weight percentage):

A. Carbon (C): ~45-55%—- major component forming the organic backbone.

B. Oxygen (O): ~30-45% — comes from carboxyl, hydroxyl, and other functional groups.

C. Hydrogen (H): ~3-6% - minor but essential in organic bonding.

D. Nitrogen (N): ~1-5% - present in amide and amine groups.
So the correct match is: A-I, B-II, C-III, D-IV.

In global atmospheric circulation, arid zones are commonly found near 30° North and South latitudes, where:

• Descending air of the Hadley cell warms and dries, creating high-pressure zones.

• These regions correspond to major deserts:
Sahara, Arabian (30°N)
Kalahari, Australian (30°S)

Other zones:
• 10° Latitude: lies in the tropics-humid.
• 60° Latitude: area of rising air, more precipitation.

• Equator (0°): Intertropical Convergence Zone (ITCZ), high rainfall.
Hence, arid areas are most common at 30° Latitude.

Tо separate and identify trace levels of high molecular weight biomolecules, LC-MS is ideal:

• Liquid Chromatography (LC): Separates complex mixtures based on interactions with the column.

• Mass Spectrometry (MS): Identifies molecules based on mass-to-charge ratio (m/z) and provides high sensitivity, even at trace levels.

Comparisons:

• GC-MS: Suitable for volatile compounds; not ideal for high MW biomolecules.
• HPLC-UV: Lacks the specificity and sensitivity of MS.
• GPC-RI: Good for polymer size exclusion, but not trace-level detection or identification.

Therefore, LC-MS is best for trace biomolecule identification.

Let's match geological processes with their resulting products:
A. Dissolution of Calcite → Travertine (IV):
Calcite (CaCO₃) dissolves in carbonic acid-rich water; when CO₂ degasses (e.g., in springs), calcite precipitates again as Travertine, a form of limestone.

B. Oxidation of Olivine → Hematite (III): Olivine (Mg,Fe)₂ SiO₄ undergoes oxidation, releasing Fe²⁺ which oxidizes further to Fe³⁺ and precipitates as Hematite (Fe₂O₃), a common weathering product.

C. Hydrolysis of Orthoclase → Kaolinite (II): Orthoclase feldspar (KAISi₃O₈) undergoes hydrolysis, especially in acidic environments, forming Kaolinite, a clay mineral.

D. Hydrolysis of Quartz → Chert (I):
Though quartz is resistant, long-term hydrolysis and recrystallization under diagenesis can produce Chert, a microcrystalline silica.
Correct match: A-IV, B-III, C-II, D-I.

According to the Solid Waste Management Rules, 2016, important criteria for site selection of sanitary landfills include:

• The landfill site must be:
≥100 meters away from rivers
≥200 meters from ponds
≥100 meters from highways or habitations
≥20 km from airports (only if the site handles > 50 tons/day of waste)

So, while several criteria exist, the rule specifies minimum 100 meters distance from rivers as a basic threshold.
Correct answer: 100 meters away from river.

Let's arrange the wildlife conservation projects chronologically:
A. Project Tiger (1973): Launched to protect Bengal tigers; India's first major speciesspecific conservation project.

C. Crocodile Conservation Project (1975): Initiated with UNDP and FAO support to prevent extinction of crocodile species.

B. Project Elephant (1992): Focused on elephant corridors and human-elephant conflict.

D. GOI-UNDP Sea Turtle Project (1999-2000): For sea turtle nesting site protection and community awareness.
Chronological order: Project Tiger → Crocodile Conservation → Project Elephant → Sea Turtle Project, i.e., A, C, B, D.

In water treatment, when chlorine is added, some of it reacts with organic matter, metals, or microorganisms before a residual is left:

Chlorine Demand = Total chlorine added - Residual chlorine after contact period

This value indicates how much chlorine is consumed in oxidation and disinfection before any leftover (free or combined) remains.
• Free available chlorine: Cl₂ not bound to organic N.
• Combined available chlorine: Part of chlorine bound with ammonia.
Total chlorine: Sum of free + combined chlorine.
So, the difference between added and residual chlorine is called Chlorine demand.

Let’s match chemicals with their function in water/wastewater treatment:

A. FeCl₃ → IV. Coagulation Aid: Ferric chloride is a common coagulant, neutralizing charges on suspended solids to promote sedimentation.

B. Ca(OH)₂ → III. Soda-Lime Process (Hardness Removal): Lime (calcium hydroxide) precipitates calcium and magnesium ions, removing water hardness. 

C. CO₂ → II. Lowering pH: After soda-lime precipitation, CO₂ is bubbled in to lower pH by forming carbonic acid, preventing scale formation.

D. O₂ → I. Enhancing microbial growth: In activated sludge process, oxygen is aerated into wastewater to support aerobic bacteria, which break down organic matter.