Previous Year UPSC Questions

Explanation

Statement I is Correct: It is estimated that around 4-8 percent of the world’s carbon dioxide (CO₂) emissions come from the manufacture of cement, making it a major contributor to global warming

Statement II is correct but doesn’t explain statement I: Silica-bearing clay is mixed with limestone while manufacturing cement. Limestone, primarily composed of calcium carbonate (CaCO₃)₃), begins to decompose at temperatures around 825°C (1517°F). This process, called calcination, breaks down the limestone into calcium oxide (CaO) and carbon dioxide (CO₂). Thus the step of mixing Silica bearing clay and limestone contribute to the Carbon dioxide emission from cement industry.

Statement III is correct and explains Statement I: A significant portion of the emissions are an intrinsic part of the production of clinker. In the process of making cement clinker, limestone, which is primarily calcium carbonate (CaCO₃)₃), is heated to high temperatures (1450°C or 2640°F) in a kiln. This process, called calcination, decomposes the limestone into calcium oxide (CaO), commonly known as lime, and carbon dioxide (CO₂). The lime then reacts with other raw materials like clay and silica to form the clinker, which is the main ingredient in cement.

Explanation

COP 28 was held in Dubai, UAE in December 2023. It introduced the COP28 Declaration on Climate and Health to reduce health sector greenhouse gas emissions, enhance climate-resilient health systems, and address climate-related health risks like air pollution and extreme weather. $1 billion was pledged by entities like the Rockefeller Foundation and Green Climate Fund for climate-health initiatives.

Statement I is correct: India abstained from signing due to concerns over reducing greenhouse gas emissions from cooling systems critical for healthcare infrastructure, especially in remote areas. Highlighted that cooling systems for vaccines and medicines ensure healthcare resilience, and decarbonization could disrupt service delivery. This aligned with India’s G20 presidency (2023) focus on resilient healthcare.

Statement II is incorrect: The COP28 Declaration is non-binding, encouraging voluntary actions like assessing health sector emissions, developing action plans, and promoting low-carbon health systems, active mobility, and sustainable diets. It operates outside UNFCCC/Paris Agreement frameworks, not mandating decarbonization. India raised concerns about cooling-related emissions feasibility, not mandatory requirements.

Statement III is correct: India argued that decarbonizing the health sector, particularly cooling systems for vaccine storage and hospitals, could compromise healthcare resilience in tropical climates and remote areas. A Kenyan delegate noted India’s concern that emission reductions could hinder medical demands in underserved regions. India’s G20 priorities (2023) emphasized healthcare access, medical countermeasures, and digital health platforms, supported by its low per-capita emissions (<4% of global GHG emissions) and developing nation status.

Explanation

Scientific studies confirm that Earth’s rotation (affecting day length) and axis orientation (causing polar motion) are shifting due to climate-driven factors--notably melting polar ice, glacier retreat, and groundwater depletion. These changes lead to mass redistribution, altering Earth’s moment of inertia, which in turn causes a rotational slowing (e.g., 1.33 milliseconds per century) and polar wander (axis shifts of 10-20 cm/year). Since 1980, Earth’s spin axis has shifted nearly 4 meters. The Chandler wobble, a natural axis oscillation, is also amplified by these mass changes.

Statement I is correct: Mass redistribution--e.g., Greenland losing 4,700 Gt and Antarctica 2,720 Gt (1992-2020), and 1.6 trillion tons of groundwater pumped since 1990--shifts mass toward the equator, slowing rotation and shifting the axis.

Statement II is correct: Solar flares and coronal mass ejections (CMEs) release up to 10° joules of energy, impacting the ionosphere and thermosphere (80-1000 km altitude). These cause geomagnetic storms, disrupting satellites, radio, and triggering auroras. However, per NASA and NOAA, they do not affect rotation or axis shifts, since they alter magnetic fields and atmospheric density, not mass distribution.

Statement III is correct: Climate-driven polar ice melt and groundwater depletion (e.g., Punjab & Haryana in India) shift mass equatorward, increasing moment of inertia, thus slowing rotation and causing axis drift, as confirmed by NASA and Nature Geoscience.

Explanation

Article 6 of the Paris Agreement (2015, COP21) provides a framework for international cooperation to achieve climate goals through market-based and non-market-based mechanisms, enabling countries to meet their Nationally Determined Contributions (NDCs). It’s central to discussions on climate finance, GHG reduction, and SDG alignment.

Statement I is correct:

Article 6 is a cornerstone of the Paris Agreement, frequently discussed at COP summits--COP26 (Glasgow, 2021) and COP29 (Baku, 2024). It enables international cooperation for NDCs, addresses carbon markets and non-market approaches (NMAs), and mobilizes up to $1 trillion in climate finance by 2050. Highlighted by the World Bank and UNFCCC, it ensures environmental integrity and supports sustainable development. In India, with <4% of global GHG emissions, Article 6 is key in climate negotiations. Delays in rule finalization--e.g., COP25 (Madrid, 2019)--due to concerns like double counting underscore its importance.

Statement II is correct:

Article 6.2 allows bilateral trading of ITMOs with corresponding adjustments to avoid double counting. Article 6.4 sets up a UN-supervised Paris Agreement Crediting Mechanism (PACM), succeeding the Kyoto Protocol’s CDM, issuing A6.4ERs with 2% cancellation and 5% share for the Adaptation Fund. As per the World Bank and IISD, these rules--finalized at COP26 and advanced at COP29--enhance market integrity and climate finance. This explains Statement I, as carbon markets drive debates on market integrity, double counting, and private sector investment (e.g., $1 trillion potential by 2050).

Statement III is correct:

Article 6.8 promotes non-market approaches (NMAs) like tech transfers, policy coordination, and adaptation finance. Recognized by UNFCCC and Legal Response International, NMAs support equity, climate resilience, and SDGs, especially for nations like India, making Article 6 central in climate talks. This also explains Statement I, as NMAs address equity and cooperation, key topics in climate negotiations, especially for developing nations like India

Explanation

The Nature Solutions Finance Hub for Asia and the Pacific was launched by the Asian Development Bank (ADB) on December 4, 2023, during COP28 in Dubai to mobilize $2 billion by 2030 for nature-based solutions such as reforestation, mangrove restoration, and sustainable agriculture. It aims to address climate change and biodiversity loss using blended finance, guarantees, and impact-linked payments to attract private capital, supporting SDG 13 (Climate Action) and SDG 15 (Life on Land). Partners include the OPEC Fund, AFD, Saudi Fund for Development, ASEAN Catalytic Green Finance Facility, IUCN, WWF, and Conservation International. ADB’s Mandate:

Established in 1966, headquartered in Manila, with 68 members (49 from Asia-Pacific). Provides $22 billion annually, committed $100 billion for climate finance (2019-2030). In 2023, 40% of approvals were climate-focused, including $434.25 million for Assam Solar Park and Rs 2,346 crore for the Ahmedabad Peri-Urban Project. Supports ecosystem restoration, biodiversity conservation, and sustainable development. Global Context: Nature-based solutions absorb 55% of carbon through forests, oceans, and land ecosystems, vital for the Asia-Pacific, where 2/3 of GDP is nature-dependent. India’s Context: India, an ADB member, benefits from climate finance (e.g., $434.25 million for Assam solar park, Rs 2,346 crore for Ahmedabad Peri-Urban Project).Challenges include land acquisition issues, highlighting social safeguards. Options (b), (c) & (d) are incorrect: (b) AIIB (est. 2016, Beijing) focuses on infrastructure, not involved in this ADB-led hub. (c) NDB (est. 2015, BRICS, Shanghai) supports green energy but not linked to the hub. (d) IBRD (World Bank, est. 1944, Washington D.C.) supports climate goals but not part of this initiative.

Explanation

Direct Air Capture (DAC) is an emerging negative emission technology that extracts carbon dioxide (CO₂) directly from the atmosphere. It is gaining attention for its potential to mitigate climate change by enabling carbon sequestration, utilization in products, and synthetic fuel production

Statement I is correct:

DAC uses chemical processes with liquid solvents (e.g., potassium hydroxide) or solid sorbents to extract CO₂ from the atmosphere. Captured CO₂ is sequestered in deep geological formations like saline aquifers or depleted oil/gas reservoirs for permanent storage, preventing atmospheric release. As of 2024, 27 DAC plants capture about 0.01 Mt CO₂/year, with plans for 130 facilities targeting 65 Mt CO₂/year by 2030 (IEA Net Zero Emissions scenario). DACCS is critical for carbon dioxide removal (CDR), essential to limit warming to 1.5°C (NASA, IPCC). Especially important for hard-to-abate sectors (e.g., aviation). India’s low per-capita emissions (<4% global GHG) make DACCS a strategic offset tool.

Statement II is correct:

CO₂ is a feedstock for industrial uses:

Plastics production (polycarbonates, polyurethanes) locks CO₂ for decades to centuries, offering durable sequestration. Food processing: carbonation of beverages, modified atmosphere packaging, with a global CO₂ market of 230 Mt/year. WRI highlights CO₂ use in plastics/concrete as more durable than short-term uses like beverages. DAC CO₂ use supports India’s food processing sector (Make in India focus). Despite costs ($400-740/tCO), policy support (e.g., US 45Q tax credits) enhances viability.

Statement III is correct:

DAC CO₂ combined with renewable hydrogen produces synthetic kerosene (power-to-liquid fuels) via processes like Fischer-Tropsch. SAFs are drop-in fuels compatible with existing aircraft, helping decarbonize aviation. DACCU mitigates CO₂ and non-CO₂ effects (contrails). Costs currently $1.50-4.50/gallon, expected to fall by 2050. India emits about 2% global aviation GHG, potentially benefiting from SAF adoption to meet CORSIA goals.

Explanation

Peacock Tarantula Overview Scientific Name: Poecilotheria metallica, also Gooty tarantula. Status: Critically Endangered, IUCN Red List. Description: Arboreal spider, Theraphosidae family (Arachnida, Araneae), known for vibrant metallic blue coloration. Habitat: Endemic to <100 sq km of deciduous forests in Andhra Pradesh (Nandyal, Giddalur, Seshachalam Biosphere Reserve) and Tamil Nadu (Pakkamalai Reserve Forests, Villupuram, Tirumala foothills). Threats: Habitat loss from deforestation, logging, firewood harvesting, and illegal pet trade. Protection: CITES Appendix II (2019) bans export without permits. Diet and Behavior:

Carnivorous, feeds on flying insects (moths, crickets) and occasionally small vertebrates (mice, small birds). Photosensitive, flees bright light, may bite if provoked with medically significant venom causing pain, nausea, dizziness (no fatalities). Constructs asymmetric funnel webs in tree holes. Spiderlings start terrestrial, transition to arboreal.

Statement I is incorrect: The Peacock tarantula is an arachnid (class Arachnida, order Araneae, family Theraphosidae), not a crustacean (class Crustacea, e.g., crabs, shrimp).

Statement II is correct: Is endemic to a small area (<100 sq km) of deciduous forests in Andhra Pradesh and Tamil Nadu.

Statement III is correct: Poecilotheria metallica is an arboreal spider, living in tree holes and constructing asymmetric funnel webs to capture flying insects.

Explanation

India, the third-largest global CO₂ emitter (2.8 Gt CO₂, 2023), has low per capita emissions (1.9-2.0 t CO₂/capita, 2022-2023) due to its 1.43 billion population (2022). Coal dominates power sector (75-76% electricity generation), followed by industry and transport.

Statement I is incorrect: Per capita CO₂ emissions measure annual emissions per person. IEA (2024) reports India’s at 2.0 t CO₂/capita (2023), Statista (2024) cites 1.89-2.0 t CO₂/capita (2022-2023), up from 1.79 t CO₂/capita (2021) due to economic growth and coal reliance. Our World in Data (2022) confirms 1.9 t CO₂/capita, below global average (4.6 t CO₂/capita) but above 0.5 t CO₂/capita. Worldometer (2022) notes 1.89 t CO₂/capita, historically 0.44 t (1980). Low emissions reflect large population and biomass use (13% lack electricity, Carbon Brief).

Statement II is correct: CO₂ emissions from fuel combustion (coal, oil, natural gas) reached 2.8 Gt CO₂ (2023, IEA), making India the second-largest emitter in Asia-Pacific after China (12.6 Gt CO₂). Emissions grew 7.2% (2023) due to coal-powered electricity (75% generation) and industrial growth (steel, cement).

Statement III is correct: Electricity and heat production, driven by coal-fired power plants (75% generation, 1,317 TWh, 2023, CEA Annual Report 2023-24), is India’s largest CO₂ source, contributing over 50% emission increase (1.4 Gt COe, Statista). Carbon intensity is 713 g CO₂/kWh, above global average (480 g CO₂/kWh). Industrial processes (cement, steel) and transport (oil-based) are secondary sources.

Explanation

The question evaluates the accuracy of botanical classifications for five plants: Cassava, Ginger, Malabar spinach, Mint, and Papaya. Key Definitions:

Woody shrub: A perennial plant with multiple woody stems branching from the base, typically under 6 m tall. Herb: A non-woody plant, often perennial or annual, with soft stems. Pseudostem: A false stem formed by tightly rolled leaf sheaths, not a true woody stem. Herbaceous climber: A non-woody plant that climbs or twines using support. Annual: Completes its life cycle in one year; perennial lives multiple years.

Pair 1 is correctly matched(Cassava - Woody Shrub):

Cassava (Manihot esculenta Crantz, Euphorbiaceae) is a tropical root crop from South America (Brazil, Paraguay). FAO and ScienceDirect classify it as a perennial woody shrub with tuberous roots (tapioca), grown as an annual. It reaches 1-3 m, with woody stems persisting in tropical climates.

Pair 2 is correctly matched(Ginger - Herb with Pseudostem):. Ginger (Zingiber officinale, Zingiberaceae) is a herbaceous perennial, grown as an annual for rhizomes. National Horticulture Board and ScienceDirect confirm its pseudostem (rolled leaf sheaths, 0.5-1.5 m) is not woody, distinguishing it from shrubs.

Pair 3 is correctly matched (Malabar Spinach - Herbaceous Climber): Malabar spinach (Basella alba/rubra, Basellaceae) is a fast-growing vine with soft, fleshy stems. ResearchGate, ICAR, and Missouri Botanical Garden classify it as a perennial herbaceous climber, twining on supports, grown as an annual in non-tropical areas.

Pair 4 is incorrectly matched (Mint - Annual Shrub): Mint (Mentha species, Lamiaceae) is a herbaceous perennial with soft, non-woody stems, spreading via runners. Indian Spices Board and Missouri Botanical Garden confirm it’s not an annual or shrub, regrowing from rhizomes yearly.

Pair 5 is incorrectly matched (Papaya - Woody Shrub): Papaya (Carica papaya, Caricaceae) is a tree-like herb or large herbaceous plant (3-10 m), with a single, hollow, fibrous stem, not woody. ICAR, ScienceDirect, and Missouri Botanical Garden classify it as a herbaceous perennial or small tree, short-lived (5-10 years), not a woody shrub.

Explanation

Oxygen production is critical for Earth’s atmosphere, primarily driven by photosynthesis in marine and terrestrial ecosystems.

Statement I is incorrect: Oceans, not rainforests (Amazon, Congo), are the primary oxygen producers. NOAA estimates 50-80% of global oxygen from marine phytoplankton in the photic zone (top 200 meters). NASA cites 50-85%, with Prochlorococcus (a cyanobacterium) contributing 5-20%. Rainforests produce ~28% (National Geographic, WWF), with other terrestrial plants adding ~2%. Oceans’ dominance stems from 71% Earth’s surface and phytoplankton’s rapid turnover (days vs. decades for trees).

Statement II is correct: Marine phytoplankton (diatoms, dinoflagellates) and photosynthetic bacteria (cyanobacteria, e.g., Prochlorococcus) are the main oceanic oxygen producers. NOAA and Smithsonian confirm 50-80% of global oxygen from oceanic photosynthesis, with NASA and WWF estimating 50-85%, including 5-20% from Prochlorococcus. Photosynthesis in the photic zone uses sunlight, CO₂, and nutrients, supporting the marine food web and atmospheric oxygen. The ~50% estimate is conservative but accurate.

Statement III is correct: Well-oxygenated surface water has high dissolved oxygen (DO) (5-10 mg/L, up to 12-15 mg/L in cold, turbulent conditions, per USGS). Atmospheric air contains 21% oxygen (~210,000 ppm, 210 g/L). Surface water’s DO (0.015 g/L) is ~14,000 times less than air, due to low oxygen solubility, confirming it cannot hold "several folds higher" oxygen.