UPSC Environment PYQ 2025
17.
Regarding Peacock tarantula (Gooty tarantula), consider the following statements:
I. It is an omnivorous crustacean.
II. Its natural habitat in India is only limited to some forest areas.
III. In its natural habitat, it is an arboreal species.
Which of the statements given above is/are correct?
(a) I only
(b) I and III
(c) II only
(d) II and III
Correct Answer:
(d) II and III
Explanation:
Statement I – Incorrect
Peacock tarantula (Gooty tarantula) is carnivorous/insectivorous, not omnivorous.
Statement II – Correct
Its natural distribution in India is highly restricted.
It is endemic to limited forest areas of Andhra Pradesh, mainly the Eastern Ghats.
Hence, its habitat is only limited to some forest areas.
Statement III – Correct
In its natural habitat, the Peacock tarantula is an arboreal species.
It lives in tree holes and tree trunks, not on the ground.
What is the meaning of arboreal species?
An arboreal species is a species that lives primarily in trees, rather than on the ground or in water.
16.
Which organization has enacted the Nature Restoration Law (NRL) to tackle climate change and biodiversity loss?
(a) The European Union
(b) The World Bank
(c) The Organization for Economic Cooperation and Development
(d) The Food and Agriculture Organization
Correct Answer:
(a) The European Union
Explanation:
Option (a) The European Union – Correct
The Nature Restoration Law (NRL) has been enacted by the European Union.
It is a legally binding law aimed at:
Restoring degraded ecosystems,
Addressing biodiversity loss,
Supporting climate change mitigation and adaptation.
Key Distinction (UPSC Favourite)
Legally binding law → Mandatory + enforceable.
Declaration / pledge → Voluntary + no legal penalty.
Memory Trick:
“Binding means court-backed.”
👉 If it’s legally binding, a court can step in when rules are broken.
Important UPSC nuance:
Punishment ≠ jail automatically.
Enforcement is usually financial or regulatory, unless a domestic law adds criminal liability.
15.
Which one of the following launched the ‘Nature Solutions Finance Hub for Asia and the Pacific’?
(a) The Asian Development Bank (ADB)
(b) The Asian Infrastructure Investment Bank (AIIB)
(c) The New Development Bank (NDB)
(d) The International Bank for Reconstruction and Development (IBRD)
Correct Answer:
(a) The Asian Development Bank (ADB)
Explanation:
Option (a) The Asian Development Bank (ADB) – Correct
The Asian Development Bank (ADB) launched the Nature Solutions Finance Hub for Asia and the Pacific.
The hub aims to:
Scale up nature-based solutions (NbS),
Mobilise public and private finance,
Support climate action, biodiversity conservation, and ecosystem restoration in the Asia-Pacific region.
Asian Development Bank (ADB)
Top 3 Facts for UPSC
1️⃣ Establishment, Headquarters & Nature
Established: 1966
Headquarters: Manila, Philippines
Type: Multilateral Development Bank (MDB)
Region of operation: Asia–Pacific
👉 UPSC frequently combines year + HQ + region in one MCQ.
2️⃣ Membership & Shareholding (High-Yield Trap Area)
Total Members: 68
49 regional
19 non-regional
Largest shareholders: Japan and the United States (jointly)
Voting power: Based on capital subscription, not equal voting.
Presidency convention: President is traditionally from Japan.
👉 UPSC loves testing “ADB is not Asia-only” and Japan–USA dominance.
3️⃣ Role in Development & Climate Finance
Provides:
Loans, grants, technical assistance
Key focus areas:
Infrastructure
Poverty reduction
Climate change mitigation & adaptation
Launched: Nature Solutions Finance Hub for Asia and the Pacific
👉 Links ADB + climate finance + nature-based solutions (current affairs + static).
14.
Consider the following statements:
Statement I:
At the 28th United Nations Climate Change Conference (COP28), India refrained from signing the ‘Declaration on Climate and Health’.
Statement II:
The COP 28 Declaration on Climate and Health is a binding declaration; and if signed, it becomes mandatory to decarbonize health sector.
Statement III:
If India's health sector is decarbonized, the resilience of its health-care system may be compromised.
Which one of the following is correct in respect of the above statements?
(a) Both Statement II and Statement III are correct and both of them explain Statement I
(b) Both Statement II and Statement III are correct but only one of them explains Statement I
(c) Only one of the Statements II and III is correct and that explains Statement I
(d) Neither Statement II nor Statement III is correct
Correct Answer:
(c) Only one of the Statements II and III is correct and that explains Statement I
Explanation:
It was a medium level question because of the statement 2.
Statement I – Correct
At COP28, India did not sign the Declaration on Climate and Health.
This was officially reported and linked to India’s concerns regarding its health-sector priorities.
Statement II – Incorrect
The Declaration on Climate and Health is NOT legally binding.
COP declarations are political/voluntary commitments, not treaties.
Signing does not create a mandatory legal obligation to decarbonize the health sector.
Hence, Statement II is factually wrong.
Statement III – Correct
India expressed concern that rapid or rigid decarbonisation of the health sector could:
Affect energy security
Reduce operational flexibility
Compromise health-system resilience, especially during emergencies
This concern explains why India refrained from signing the declaration.
Conclusion:
Only Statement III is correct, and it explains Statement I.
13.
Consider the following:
I. Cigarette butts
II. Eyeglass lenses
III. Car tyres
How many of them contain plastic?
(a) Only one
(b) Only two
(c) All the three
(d) None
Correct Answer:
(c) All the three
Explanation:
Statement I: Cigarette butts – Correct
Cigarette filters are made of cellulose acetate, which is a synthetic plastic polymer.
Hence, cigarette butts contain plastic.
Statement II: Eyeglass lenses – Correct
Most modern eyeglass lenses are made from plastic polymers such as polycarbonate or CR-39 (Columbia Resin 39).
Hence, eyeglass lenses contain plastic.
Statement III: Car tyres – Correct
Car tyres contain synthetic rubber, which is derived from petroleum-based polymers (plastics).
Tyres are therefore partly plastic in composition.
Conclusion:
All three listed items contain plastic.
Polymer = a chemical substance made of long chains of repeating units.
Plastic = a type of polymer that is processed and shaped for practical use.
Explanation:
Meaning of “Polymer”
A polymer is a large molecule formed by repeating small units called monomers.
Polymers can be:
Natural → cellulose, rubber, proteins
Synthetic → polyethylene, nylon, PVC
A polymer is a chemical category, not a finished product.
Meaning of “Plastic” (in this question)
Plastic refers to synthetic polymers that:
Can be moulded, shaped, or hardened using heat or pressure.
Are used in manufactured products.
Examples:
Cellulose acetate (cigarette filters)
Polycarbonate (eyeglass lenses)
Synthetic rubber polymers (car tyres)
Difference between Polymer and Plastic
Polymer
Chemical concept.
Refers to molecular structure.
Can be natural or synthetic.
Example: cellulose, natural rubber.
Plastic
Industrial/material concept.
Always a processed synthetic polymer.
Designed for human use.
Example: plastic lenses, plastic packaging.
Why all three items “contain plastic”
Cigarette butts → cellulose acetate polymer used as plastic filter.
Eyeglass lenses → polycarbonate / CR-39 plastic polymers.
Car tyres → synthetic rubber polymers + plastic additives.
Thus, plastic = usable form of certain polymers.
Memory Trick:
“All plastics are polymers, but not all polymers are plastics.”
Is plastic is made from the petroleum waste?
Correct Answer:
No.
Plastic is not made from petroleum waste.
Plastic is made from petroleum fractions (by-products) obtained during crude oil refining.
Explanation:
Petroleum waste ❌
Waste means useless, discarded material.
Petroleum waste is not used to make plastic.
What is actually used ✅
Plastic is made from petrochemical feedstocks, such as:
Ethylene
Propylene
These are obtained as by-products during:
Crude oil refining
Natural gas processing
Key distinction (very important for UPSC):
By-product ≠ Waste
By-product → useful secondary output
Waste → unwanted, discarded material
Process in simple terms:
Crude oil → refined into fuels
Some fractions → converted into monomers
Monomers → polymerised → plastics
Therefore:
Plastics are made from valuable petrochemical fractions,
not from petroleum waste.
Memory Trick:
“Plastic from petro-products, not from petro-waste.”
12.
Consider the following statements:
Statement I:
Studies indicate that carbon dioxide emissions from cement industry account for more than 5% of global carbon emissions.
Statement II:
Silica-bearing clay is mixed with limestone while manufacturing cement.
Statement III:
Limestone is converted into lime during clinker production for cement manufacturing.
Which one of the following is correct in respect of the above statements?
(a) Both Statement II and Statement III are correct and both of them explain Statement I
(b) Both Statement II and Statement III are correct but only one of them explains Statement I
(c) Only one of the Statements II and III is correct and that explains Statement I
(d) Neither Statement II nor Statement III is correct
Correct Answer:
(a) Both Statement II and Statement III are correct and both of them explain Statement I
Explanation:
Statement I – Correct
Cement industry contributes more than 5% (≈8%) of global anthropogenic carbon dioxide (CO₂) emissions.
Statement II – Correct
Cement manufacturing involves mixing silica-bearing clay with limestone.
This process requires high-temperature heating in kilns.
The energy used (mainly fossil fuels) for heating releases CO₂ as combustion emissions.
Hence, Statement II explains Statement I through energy-related emissions.
Statement III – Correct
During clinker production, limestone (calcium carbonate, CaCO₃) is converted into lime (calcium oxide, CaO).
This calcination reaction releases CO₂ directly:
CaCO₃ → CaO + CO₂
This is a process emission and accounts for about half of cement-sector CO₂ emissions.
Hence, Statement III also explains Statement I.
Conclusion:
Cement emissions arise from:
Process emissions (chemical conversion of limestone), and
Energy emissions (high-temperature heating during mixing and clinker formation).
Therefore, both Statements II and III explain Statement I.
Kilns are high-temperature industrial furnaces used to heat materials to very high temperatures to cause physical or chemical changes.
Explanation:
What is a Kiln?
Kilns are high-temperature industrial furnaces used to heat materials to very high temperatures to cause physical or chemical changes.
In cement manufacturing:
Kilns heat a mixture of limestone (calcium carbonate) and silica-bearing clay to about 1,450°C.
This high temperature causes:
Calcination:
Calcium carbonate (CaCO₃) → Calcium oxide (CaO) + Carbon dioxide (CO₂)
Formation of clinker, the intermediate product of cement.
Why kilns are important for CO₂ emissions:
Fuel combustion in kilns releases CO₂ (energy-related emissions).
Chemical breakdown of limestone releases CO₂ (process emissions).
Memory Trick:
“Kiln = Kill CO₃ → CO₂”
👉 Kiln heat breaks CaCO₃, releasing CO₂.
11.
The World Bank warned that India could become one of the first places where wet-bulb temperatures routinely exceed 35°C. Which of the following statements best reflect(s) the implication of the above-said report?
I. Peninsular India will most likely suffer from flooding, tropical cyclones and droughts.
II. The survival of animals including humans will be affected as shedding of their body heat through perspiration becomes difficult.
Select the correct answer using the code given below.
(a) I only
(b) II only
(c) Both I and II
(d) Neither I nor II
✅ Correct Answer:
(c) Both I and II
Explanation:
Statement I – Correct
The World Bank report links extreme heat and humidity with intensification of the hydrological cycle.
This leads to:
Heavier monsoon rainfall → flooding risks
Warmer oceans → increased frequency/intensity of tropical cyclones
Heat extremes → higher probability of droughts
Peninsular India is particularly vulnerable due to coastal exposure and monsoon dependence.
✔ Hence, Statement I correctly reflects an implication of the report.
Statement II – Correct
Wet-bulb temperature of 35°C represents a physiological survivability limit.
At this threshold:
Sweat cannot evaporate
Body cannot shed heat
Even healthy humans and animals face fatal heat stress.
This is a central finding of the World Bank warning.
✔ Hence, Statement II is correct.
Final Conclusion:
Both statements correctly reflect the implications of the World Bank report.
What is perspiration ?
Perspiration is the process by which the human body releases sweat through the skin to regulate body temperature.
Explanation (UPSC-Oriented):
Perspiration occurs through sweat glands present in the skin.
Sweat is mainly water with salts.
When sweat evaporates, it:
Removes heat from the body
Helps in cooling the body
This is the primary mechanism of thermoregulation in humans.
Why it matters in climate-related questions:
In hot and humid conditions, sweat does not evaporate easily.
As a result:
Body cannot lose heat effectively
Heat stress increases
This is why high wet-bulb temperatures are dangerous.
One-line UPSC Definition:
Perspiration is the secretion of sweat from the skin that helps regulate body temperature through evaporative cooling.
Memory Trick:
“Perspiration = Sweat to shed heat.”
10.
Consider the following statements:
Statement I:
Of the two major ethanol producers in the world, i.e., Brazil and the United States of America, the former produces more ethanol than the latter.
Statement II:
Unlike in the United States of America, where corn is the principal feedstock for ethanol production, sugarcane is the principal feedstock for ethanol production in Brazil.
Which one of the following is correct in respect of the above statements?
(a) Both Statement I and Statement II are correct and Statement II explains Statement I
(b) Both Statement I and Statement II are correct but Statement II does not explain Statement I
(c) Statement I is correct but Statement II is not correct
(d) Statement I is not correct but Statement II is correct
✅ Correct Answer
👉 (d) Statement I is not correct but Statement II is correct
🧠 Explanation
Let us analyse both statements carefully, fact-by-fact 👇
🔹 Statement I
“Brazil produces more ethanol than the United States.” ❌
This statement is incorrect.
The United States of America is the world’s largest producer of ethanol, consistently producing more ethanol than Brazil.
Brazil usually ranks second, not first.
✔️ Therefore, Statement I is wrong.
🔹 Statement II
“Corn is the main feedstock in the USA, while sugarcane is the main feedstock in Brazil.” ✅
This statement is absolutely correct.
USA: Ethanol is mainly produced from corn (maize).
Brazil: Ethanol is mainly produced from sugarcane, which is more energy-efficient and has a better energy balance.
✔️ Therefore, Statement II is correct.
🔗 Do the statements explain each other?
Even though sugarcane-based ethanol is more efficient, it does NOT make Brazil the largest producer.
Total production depends on scale, land area, industrial capacity, and policy support, where the USA leads.
👉 Hence, Statement II does NOT explain Statement I.
🔹 1️⃣ What does energy efficiency mean here?
In ethanol production, energy efficiency means:
How much usable energy (ethanol) you get compared to the energy you spend to produce it.
Energy spent includes:
Growing the crop 🚜
Fertilisers & irrigation 💧
Harvesting & transport 🚛
Processing & distillation ⚙️
🔹 2️⃣ What is energy balance?
Energy balance (also called Energy Return on Energy Invested – EROEI) means:
Energy output ÷ Energy input
If the value is high, the fuel is efficient
If the value is low, the fuel is energy-intensive
🔹 3️⃣ Why is sugarcane ethanol more energy-efficient?
🌱 (a) Natural advantage of sugarcane
Sugarcane already contains fermentable sugar
Less processing is needed to convert it into ethanol
🔥 (b) Use of bagasse (very important UPSC point)
Bagasse = fibrous residue left after extracting juice
In Brazil, bagasse is burnt to generate electricity & steam for ethanol plants
This reduces external energy inputs
👉 Result: Ethanol production becomes self-powered.
🔹 4️⃣ Sugarcane vs Corn (Key Conceptual Comparison)
🍬 Sugarcane ethanol (Brazil)
High photosynthetic efficiency
Uses bagasse for energy
Energy balance ≈ 7–9 : 1
👉 For every 1 unit of energy used, 7–9 units of energy are produced
🌽 Corn ethanol (USA)
Starch must be converted to sugar first (extra steps)
Heavy use of fertilisers, fossil fuels
Energy balance ≈ 1.3–1.6 : 1
👉 Much lower net energy gain
🔹 5️⃣ Why does UPSC say “better energy balance”?
Because sugarcane ethanol:
Uses renewable by-products
Needs less fossil fuel input
Produces much higher net energy output
Hence, it is:
More energy-efficient
More environment-friendly
Lower carbon footprint
🧠 Memory Trick
🍬 “Cane powers itself”
Sugar → Ethanol
Bagasse → Energy
🌽 “Corn needs help”
Needs more fuel to make fuel
⚡ Exam-Ready One-Liner
Sugarcane ethanol has a better energy balance because it yields much more energy than the energy invested, largely due to the use of bagasse as a renewable energy source during processing.
9.
Artificial way of causing rainfall to reduce air pollution makes use of:
(a) Silver iodide and potassium iodide
(b) Silver nitrate and potassium iodide
(c) Silver iodide and potassium nitrate
(d) Silver nitrate and potassium chloride
✅ Correct Answer
(a) Silver iodide and potassium iodide
🧠 Explanation
This question is about artificial rainfall, commonly known as cloud seeding 🌧️.
Let us understand the science clearly 👇
🔹 What is cloud seeding?
Cloud seeding is an artificial technique used to enhance rainfall by adding nucleating agents into clouds so that water droplets or ice crystals grow larger and fall as rain.
🔹 Why is it used to reduce air pollution?
Rain helps in washing out suspended particulate matter (PM2.5, PM10) and soluble pollutants from the atmosphere. This process is called wet deposition.
🔬 Role of Chemicals Used
Silver iodide (AgI) ✅
Acts as an ice-nucleating agent
Its crystal structure is similar to ice
Helps supercooled water droplets freeze and grow into rain-bearing particles
Potassium iodide (KI) ✅
Helps in effective dispersion of silver iodide particles
Sometimes used as a supporting seeding agent
👉 Therefore, silver iodide + potassium iodide are correctly associated with artificial rainfall.
Artificial rainfall through cloud seeding commonly uses silver iodide because its structure resembles ice crystals, enabling precipitation.
📘 Meaning of Nucleating Agents (Simple + UPSC-oriented)
Nucleating agents are substances that provide a surface or centre (nucleus) on which small particles (like water molecules) can start clustering together to form larger particles.
👉 In simple words:
Nucleating agent = “starter point” that helps droplets or crystals begin to form
🔬 Why are nucleating agents needed?
In nature, pure water vapour does not easily turn into rain or ice on its own.
It needs a seed or nucleus to start the process.
Nucleating agents help in:
🌧️ Formation of rain droplets
❄️ Formation of ice crystals
☁️ Growth of cloud particles to a size heavy enough to fall as precipitation
☁️ Nucleating Agents in Cloud Seeding (Very Important for UPSC)
In artificial rainfall (cloud seeding):
Silver iodide (AgI) is used as a nucleating agent
Its crystal structure closely resembles natural ice
Water vapour sticks to it and freezes → grows → falls as rain
👉 Hence, AgI acts as an ice-nucleating agent
🌍 Natural vs Artificial Nucleating Agents
Natural nucleating agents:
Dust particles
Sea salt
Pollen
Smoke particles
Artificial nucleating agents:
Silver iodide
Potassium iodide (supporting agent)
🧠 Memory Trick
🧩 “Nucleus = Starting point”
No nucleus → no growth
Add nucleus → growth starts
Or for cloud seeding:
☁️ “AgI = Artificial Ice”
⚡ Exam-Ready One-Liner
Nucleating agents are substances that initiate the formation of droplets or ice crystals by providing a surface for condensation or freezing.
8.
Consider the following statements:
Statement I:
Circular economy reduces the emissions of greenhouse gases.
Statement II:
Circular economy reduces the use of raw materials as inputs.
Statement III:
Circular economy reduces wastage in the production process.
Which one of the following is correct in respect of the above statements?
(a) Both Statement II and Statement III are correct and both of them explain Statement I
(b) Both Statement II and Statement III are correct but only one of them explains Statement I
(c) Only one of the Statements II and III is correct and that explains Statement I
(d) Neither Statement II nor Statement III is correct
✅ Correct Answer
👉 (a) Both Statement II and Statement III are correct and both of them explain Statement I
🧠 Explanation
Let us evaluate step by step, UPSC-style 👇
Statement I: Circular economy reduces greenhouse gas emissions ✅
Circular economy focuses on reduce, reuse, recycle, repair.
This lowers energy-intensive extraction, manufacturing, and waste disposal, all of which emit greenhouse gases.
✔️ Statement I is correct.
Statement II: Circular economy reduces the use of raw materials as inputs ✅
By reusing materials, recycling products, and extending product life, demand for fresh raw material extraction decreases.
Less mining, logging, and processing = lower carbon emissions.
✔️ Statement II is correct and directly explains Statement I.
Statement III: Circular economy reduces wastage in the production process ✅
Circular systems aim for zero waste, converting waste into resources.
Reduced waste means less landfill emissions (methane) and lower energy use.
✔️ Statement III is correct and also explains Statement I.
🔍 Logical Link (Key UPSC Point)
Less raw material extraction → less energy use → fewer emissions
Less waste generation → less disposal emissions → fewer emissions
👉 Hence, both Statement II and Statement III explain Statement I.
7.
With reference to the planet Earth, consider the following statements:
I. Rainforests produce more oxygen than that produced by oceans.
II. Marine phytoplankton and photosynthetic bacteria produce about 50% of the world’s oxygen.
III. Well-oxygenated surface water contains several folds higher oxygen than that in atmospheric air.
Which of the statements given above is/are correct?
(a) I and II
(b) II only
(c) I and III
(d) None of the above statements is correct
✅ Correct Answer
(b) II only
🧠 Explanation
Let us analyse each statement carefully, UPSC-style 👇
Statement I: Rainforests produce more oxygen than oceans. ❌
This is incorrect.
Oceans are the largest oxygen producers on Earth.
Marine phytoplankton, cyanobacteria, and algae together produce more oxygen than all terrestrial forests combined, including rainforests.
👉 Hence, Statement I is wrong.
Statement II: Marine phytoplankton and photosynthetic bacteria produce about 50% of the world’s oxygen. ✅
This is correct.
Scientific estimates show that around 50% (or even slightly more) of Earth’s oxygen comes from marine photosynthesis.
UPSC often frames this as a factual environmental concept.
👉 Hence, Statement II is correct.
Statement III: Well-oxygenated surface water contains several folds higher oxygen than atmospheric air. ❌
This is incorrect.
📘 Meaning of Well-Oxygenated Surface Water
Well-oxygenated surface water refers to surface layers of rivers, lakes, seas, or oceans that contain high levels of dissolved oxygen (DO – Dissolved Oxygen).
This happens because:
🌬️ Direct contact with atmospheric air allows oxygen to diffuse into water
🌞 Photosynthesis by phytoplankton, algae, and aquatic plants releases oxygen
🌊 Waves, currents, wind mixing, and turbulence continuously replenish oxygen
In simple words 👇
Well-oxygenated surface water = surface water rich in dissolved oxygen, suitable for aquatic life
📊 Oxygen Concentration in Well-Oxygenated Surface Water
Typical dissolved oxygen (DO):
👉 6–8 mg/L (milligrams per litre)
Maximum (cold, clean, fast-moving water):
👉 Up to ~9–10 mg/L
Warm tropical surface waters:
👉 ~5–6 mg/L (still considered well-oxygenated)
🔍 Why this matters for UPSC (Conceptual Trap)
Atmospheric air:
👉 ~21% oxygen by volume
Water (even well-oxygenated):
👉 Oxygen exists only in dissolved form, measured in mg/L, not %
👉 Hence, oxygen concentration in water is far lower than in air
📌 This is why the statement “well-oxygenated surface water contains several folds higher oxygen than atmospheric air” is WRONG.
🧠 Memory Trick
💡 “Water drinks oxygen, air breathes oxygen”
Water can only hold oxygen (mg/L)
Air contains oxygen (percentage)
Or simply:
🌬️ Air = %
🌊 Water = mg/L
⚡ Exam-Ready One-Liner
Well-oxygenated surface water is surface water rich in dissolved oxygen due to atmospheric exchange and photosynthesis, typically containing 6–8 mg/L of dissolved oxygen, much lower than oxygen concentration in air
Atmospheric air contains about 21% oxygen.
Even well-oxygenated water contains much less dissolved oxygen (measured in mg/L), far lower than atmospheric concentration.
👉 Hence, Statement III is wrong.
6.
Consider the following statements:
I. Carbon dioxide (CO₂) emissions in India are less than 0.5 t CO₂/capita.
II. In terms of CO₂ emissions from fuel combustion, India ranks second in Asia-Pacific region.
III. Electricity and heat producers are the largest source of CO₂ emissions in India.
Which of the statements given above is/are correct?
(a) I and III only
(b) II only
(c) II and III only
(d) I, II and III
Correct Answer:
(c) II and III only
Explanation:
It was a medium level question because here elimination technique could be used statement 1 and 3 are extremely famous so using them and the options we can reach the answer.
Statement I – Incorrect.
India’s per capita CO₂ emissions are much higher than 0.5 t CO₂/capita (they are around ~1.8–2 t CO₂/capita). Hence, this statement is factually wrong.
Statement II – Correct.
In the Asia-Pacific region, China ranks first in CO₂ emissions from fuel combustion, and India ranks second. Therefore, this statement is correct.
Statement III – Correct.
In India, the electricity and heat production sector (mainly coal-based power generation) is the largest source of CO₂ emissions, exceeding transport and industry.
5.
With reference to ‘Direct Air Capture’, an emerging technology, which of the following statements is/are correct?
I. It can be used as a way of carbon sequestration.
II. It can be a valuable approach for plastic production and in food processing.
III. In aviation, it can be a source of carbon for combining with hydrogen to create synthetic low-carbon fuel.
Select the correct answer using the code given below.
(a) I and II only
(b) III only
(c) I, II and III
(d) None of the above statements is correct
Correct Answer:
(c) I, II and III
Explanation:
Statement I – Correct
Direct Air Capture (DAC) removes carbon dioxide (CO₂) directly from the atmosphere.
The captured CO₂ can be stored underground (geological storage), which is a form of carbon sequestration.
Statement II – Correct
Captured CO₂ can be used as a raw material:
In plastic production (carbon-based polymers).
In food processing (e.g., carbonation of beverages).
Hence, DAC supports carbon utilisation.
Statement III – Correct
In aviation, captured CO₂ can be combined with green hydrogen to produce synthetic fuels (e-fuels / synthetic aviation fuel).
These fuels are considered low-carbon, as the carbon comes from the atmosphere, not fossil sources.
Final Conclusion:
All three statements correctly describe applications of Direct Air Capture.
👉 Correct option: (c) I, II and III
Memory Trick:
“DAC = Capture → Store → Reuse → Fly.”
4.
Consider the following statements:
Statement I:
Article 6 of the Paris Agreement on climate change is frequently discussed in global discussions on sustainable development and climate change.
Statement II:
Article 6 of the Paris Agreement on climate change sets out the principles of carbon markets.
Statement III:
Article 6 of the Paris Agreement on climate change intends to promote inter-country non-market strategies to reach their climate targets.
Which one of the following is correct in respect of the above statements?
(a) Both Statement II and Statement III are correct and both of them explain Statement I
(b) Both Statement II and Statement III are correct but only one of them explains Statement I
(c) Only one of the Statements II and III is correct and that explains Statement I
(d) Neither Statement II nor Statement III is correct
Correct Answer:
(a) Both Statement II and Statement III are correct and both of them explain Statement I
Explanation:
Statement I – Correct.
Article 6 is widely discussed because it deals with international cooperation mechanisms that are central to achieving climate targets and sustainable development.
Statement II – Correct.
Article 6 provides the framework for market-based mechanisms, including international carbon markets (e.g., cooperative approaches and a centralized mechanism for emission reductions).
Statement III – Correct.
Article 6 also includes non-market approaches (Article 6.8), promoting inter-country cooperation through policy coordination, technology transfer, and capacity building to meet climate goals.
Link:
Both carbon markets (market mechanisms) and non-market approaches explain why Article 6 is a key focus in global climate and sustainability discussions.
Memory Trick:
“Article 6 = Markets + Non-markets = Global cooperation.”
3.
Consider the following statements:
Statement I:
Scientific studies suggest that a shift is taking place in the Earth’s rotation and axis.
Statement II:
Solar flares and associated coronal mass ejections bombarded the Earth’s outermost atmosphere with tremendous amount of energy.
Statement III:
As the Earth’s polar ice melts, the water tends to move towards the equator.
Which one of the following is correct in respect of the above statements?
(a) Both Statements II and III are correct and both of them explain Statement I
(b) Both Statement II and Statement III are correct but only one of them explains Statement I
(c) Only one of the Statement II and III is correct and that explains Statement I
(d) Neither Statement II nor Statement III is correct
Correct Answer:
(b) Both Statement II and Statement III are correct but only one of them explains Statement I
Explanation:
Statement I – Correct.
Observations show small but measurable changes in Earth’s rotation speed and axis orientation, influenced by redistribution of mass and external forces.
Statement II – Correct, but does NOT explain Statement I.
Solar flares and coronal mass ejections affect the upper atmosphere and magnetosphere, but they do not cause long-term shifts in Earth’s rotation or axis.
Statement III – Correct and DOES explain Statement I.
Melting of polar ice causes mass redistribution, with water moving toward lower latitudes (equator).
This redistribution alters Earth’s moment of inertia, leading to changes in rotation and axial position.
1. What is “redistribution of mass” on Earth?
Redistribution of mass means Earth’s mass moves from one place to another.
Example:
Ice melts at the poles
Melted water flows towards the equator
So, mass shifts from near the rotation axis (poles) to farther from the axis (equator).
2. What is “moment of inertia”?
Moment of inertia is a measure of how mass is distributed relative to the axis of rotation.
In simple words:
Mass closer to the axis → easier to rotate
Mass farther from the axis → harder to rotate
👉 Same principle as:
A figure skater spins faster when arms are pulled in,
Spins slower when arms are stretched out.
3. How does redistribution alter Earth’s moment of inertia?
When water moves toward the equator:
More mass goes farther from Earth’s rotation axis
This increases Earth’s moment of inertia.
4. How does this affect Earth’s rotation?
Because of conservation of angular momentum:
If moment of inertia increases →
Rotation speed slows slightly
👉 Result:
Length of day increases marginally
Rotation rate changes
5. How does this affect Earth’s axis (axial position)?
Uneven mass redistribution causes:
Wobbling or slight shift of the rotational axis
Known as polar motion / axial drift
👉 Axis does not flip, it only shifts slightly.
One-Line UPSC-Ready Explanation
Melting polar ice redistributes mass toward the equator, increasing Earth’s moment of inertia, which slightly slows rotation and causes small shifts in the rotational axis.
Memory Trick
“Mass moves out → spin slows → axis shifts.”
This is the exact physics–geography link UPSC expects you to understand.
✔ Hence, both II and III are correct, but only Statement III explains Statement I.
Memory Trick:
“Ice melts → mass shifts → axis tilts; Sun storms don’t spin Earth.”
2.
Consider the following statements:
Statement I:
Activated carbon is a good and an attractive tool to remove pollutants from effluent streams and to remediate contaminants from various industries.
Statement II:
Activated carbon exhibits a large surface area and a strong potential for adsorbing heavy metals.
Statement III:
Activated carbon can be easily synthesized from environmental wastes with high carbon content.
Which one of the following is correct in respect of the above statements?
(a) Both Statement II and Statement III are correct and both of them explain Statement I
(b) Both Statement II and Statement III are correct but only one of them explains Statement I
(c) Only one of the Statements II and III is correct and that explains Statement I
(d) Neither Statement II nor Statement III is correct
Correct Answer:
(a) Both Statement II and Statement III are correct and both of them explain Statement I
Explanation:
Keywords in question
Effluent streams are wastewater flows discharged from industries or treatment plants.
Remediate contaminants means removing, reducing, or neutralising pollutants to make the environment safe.
Statement I – Correct
Activated carbon is widely used in industrial effluent treatment and pollution control due to its high adsorption capacity.
Statement II – Correct
Activated carbon has an extremely large surface area and a porous structure, which makes it highly effective in adsorbing heavy metals and organic pollutants.
➤ This directly explains why it is effective in pollutant removal.
Extremely large surface area”
Meaning: Activated carbon has millions of tiny internal surfaces.
One gram of activated carbon can have a surface area of hundreds to thousands of square metres.
Why important: More surface area means more sites available for pollutants to stick to.
👉 Result: Higher pollutant removal capacity.
2. “Porous structure”
Meaning: Activated carbon contains numerous tiny holes (pores) throughout its structure.
These pores are of different sizes:
Micropores → trap small molecules
Mesopores → trap medium-sized pollutants
Macropores → help pollutants enter deeper pores
👉 Result: Pollutants can enter, get trapped, and remain adsorbed inside the carbon.
Why both together matter
Porous structure allows pollutants to enter.
Large surface area provides many places for pollutants to attach.
That is why activated carbon is highly effective in adsorption, especially for:
Heavy metals
Organic pollutants
Toxic chemicals in effluents
One-line UPSC Definition
Activated carbon has a highly porous structure that creates an extremely large internal surface area, enabling efficient adsorption of pollutants.
Memory Trick
“More pores → more surface → more pollution trapped.”
Statement III – Correct
Activated carbon can be produced from agricultural residues, biomass, and other carbon-rich wastes.
➤ This makes it economical and sustainable, explaining why it is an attractive tool.
Since both Statement II and Statement III justify the effectiveness and attractiveness mentioned in Statement I, both explain Statement I.
1.
Consider the following substances:
I. Ethanol
II. Nitroglycerine
III. Urea
Coal gasification technology can be used in the production of how many of them?
(a) Only one
(b) Only two
(c) All the three
(d) None
Correct Answer:
(b) Only two
Explanation:
I. Ethanol — Correct
Coal gasification produces syngas (a mixture of carbon monoxide and hydrogen).
Syngas can be converted into alcohols, including ethanol, through catalytic processes.
Hence, ethanol can be produced using coal gasification technology.
II. Nitroglycerine — Incorrect
Nitroglycerine is produced by nitration of glycerol.
Glycerol is derived mainly from fats and oils, not from coal gasification.
Hence, coal gasification is not used in nitroglycerine production.
III. Urea — Correct
Coal gasification produces hydrogen, which is used to make ammonia.
Ammonia reacts with carbon dioxide (also obtained during gasification) to produce urea.
Hence, urea can be produced using coal gasification technology.
Final Conclusion:
Coal gasification technology can be used in the production of Ethanol and Urea only.
👉 Correct Answer: (b) Only two
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