Prelims Environment
UPSC CSE PRELIMS 2025 DETAILED ANALYSIS : Environment & Ecology Part -4
The UPSC Prelims 2025 question paper continued its legacy of being unpredictable, analytical, and concept-driven. With 100 questions in General Studies Paper I, the trend clearly reflected a balanced distribution across subjects like Polity, Economy, Environment, Science & Tech, History, and Geography. Among them, Environment & Ecology stood out with a total of 13 questions, constituting a significant portion and demanding focused preparation.
Overall Nature of UPSC Prelims 2025
This year, the paper appeared moderately tougher compared to the previous year. Questions across all subjects ranged from easy to medium and difficult levels, indicating a layered testing approach. The hallmark of this year’s paper was its emphasis on core fundamentals, often intertwined with current affairs, reinforcing the need for integrated preparation.
Given below is the breakdown of the 100 questions asked in CSE Prelims 2025.
Environment & Ecology Section: Key Observations
The Environment & Ecology section in UPSC Prelims 2025 reflected a noticeable shift in focus. Rather than concentrating on static topics like species and ecological behavior, the paper leaned towards contemporary environmental issues and technological solutions. The questions tested both core concepts and awareness of current global challenges, particularly those linked to climate change and innovation.
Notable Themes Covered:
- Climate Change Mitigation Technologies – e.g., Direct Air Capture
- Artificial Weather Modification – e.g., Artificial Rainfall
- Sustainable Development and Climate Finance Mechanisms-e.g. Article 6 Paris Climate deal
The Detailed Analysis of UPSC Prelims 2025 Environment Section are as follows:
UPSC Prelims Environment & Ecology Q.
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
Answer: A
Explanation
- Artificial rain (cloud seeding) is commonly done using silver iodide (AgI) and sometimes potassium iodide (KI). These substances act as cloud condensation or ice nuclei, helping water droplets form and precipitate. Hence option (a) is the correct answer.
MOTIVATION, SOURCES AND COVERAGE OF PRELIMS QUESTION IN THE VISIONIAS SOURCES
Motivation: To test fundamental concepts.
Sources:
Coverage of the topic in the VisionIAS Current Affairs Sources
- News Today (Nov 21, 2024): Delhi Govt. seeks Centre’s permission for Cloud Seeding in the backdrop of deteriorating air quality
Coverage of Topic in the VisionIAS All India Test Series/ Sandhan/Open Test
Sandhan Vision IAS Prelims Test Series Initiative
Q. Consider the following statements regarding the cloud seeding:
1. It works only when there is enough pre-existing clouds in the atmosphere.
2. It can be done from ground-based generators or aircraft.
3. Only silver iodide or dry ice can be used in the process to aid in the formation of ice crystals.
How many statements given above are correct?
UPSC Prelims Environment & Ecology Q.
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
Answer: D
Explanation
- The US produced significantly more ethanol than Brazil in 2024, with the US producing approximately 16.1 billion gallons and Brazil producing 8.8 billion gallons. Together, the United States and Brazil produce 80% of the world’s ethanol. The vast majority of U.S. ethanol is produced from corn, while Brazil primarily uses sugarcane. Hence, Statement I is not correct but Statement II is correct.
MOTIVATION, SOURCES AND COVERAGE OF PRELIMS QUESTION IN THE VISIONIAS SOURCES
Motivation: Ethanol production is often seen in the news.
Sources:
- https://afdc.energy.gov/data/10331#:~:text=The%20United%20States%20is%20the,while%20Brazil%20primarily%20uses%20sugarcane.
- https://www.statista.com/statistics/281606/ethanol-production-in-selected-countries/
Coverage of the topic in the VisionIAS Current Affairs Sources
- PT 365 Updated II 2025: 4.6 Biofuels
- Monthly Current Affairs: March: 6.1 Biofuels
UPSC Prelims Environment & Ecology Q.
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
Answer: C
Explanation
- In a November 2022 report, the World Bank warned that India could become one of the first places in the world where wet-bulb temperatures could increase beyond the survivability threshold of 35°C.
- The World Bank report suggests that increased heat stress and difficulty in shedding body heat through perspiration will negatively impact the survival of animals, including humans. This is due to the fact that sweating, a crucial mechanism for cooling the body, becomes less effective in hot and humid conditions. When the air is already saturated with moisture, sweat cannot evaporate efficiently, and the body struggles to regulate its temperature.
- The impact will also be the increased rainfall during monsoon seasons, that could exacerbate flooding risks in the Indian peninsula. Also, there is a rising risk of frequent tropical cyclones in the region and droughts. Hence, option (c) is the correct answer.
MOTIVATION, SOURCES AND COVERAGE OF PRELIMS QUESTION IN THE VISIONIAS SOURCES
Motivation: In a November 2022 report, the World Bank warned that India could become one of the first places in the world where wet-bulb temperatures could increase beyond the survivability threshold of 35°C.
Sources:
- https://www.economist.com/asia/2023/04/02/global-warming-is-killing-indians-and-pakistanis
- https://www.livemint.com/mint-lounge/business-of-life/explained-is-india-at-risk-of-wet-bulb-temperatures-111680173072716.html
The remaining Environment & Ecology questions from UPSC Prelims 2025 are discussed in – earlier part of the series.
VisionIAS Faculty Discussion: Environment & Ecology Section Analysis of UPSC Prelims 2025
To help aspirants decode the evolving pattern and approach of UPSC Prelims 2025, our expert faculty at VisionIAS has conducted a detailed analysis session, focusing on the trends, difficulty level, question framing, and effective strategies for future preparation. This video not only breaks down the Environment & Ecology questions but also offers valuable insights on elimination techniques, source mapping, and topic prioritization for UPSC Prelims 2026.
To watch the CSE Prelims 2025 Analysis Video, click on the following link:
UPSC Prelims 2025 | GS Paper 1 | Analysis & Discussion I Geography – Environment
Prepare Smarter with VisionIAS: 10-Year PYQ Environment & Ecology Compilation
To help aspirants systematically decode trends, VisionIAS has released a comprehensive compilation of last 10 years’ Environment & Ecology PYQs (2015–2024). This document offers:
- Topic-wise categorization
- Difficulty level analysis
- Source identification
- Elimination strategies
- Micro-level sub-topic mapping
- Current affairs integration guide
Link to read and download the document: 10 year UPSC PYQ Trend Analysis : Environment
Our faculty at VisionIAS has conducted an insightful discussion on the Environment & Ecology PYQ Trend Analysis Document. This session covers key patterns, conceptual depth of questions, and strategies to tackle future Prelims papers more effectively. The discussion also highlights how our 10-year PYQ document can be used as a powerful tool for focused preparation.
To watch the discussion by our faculty, click on the link below: GS Prelims | 10 Year PYQ (2015 – 2024) | Environment
Further, understand the UPSC Prelims with VisionIAS’s Master Classes on PYQ of UPSC Prelims. This program transforms 13 years of UPSC previous year question papers into a powerful strategy- building resource. Designed to enhance your accuracy, speed, and conceptual clarity, it’s a smart way to turn UPSC PYQs into your strongest preparation tool
