Daily Prelims MCQs — Sci-Tech, Environment and Geography — 29th July 2025
- TPP
- Jul 29
- 15 min read
Welcome to today’s handpicked set of Multiple-Choice Questions (MCQs) from the Science, Technology, Environment and Geography — crafted specially for the UPSC Prelims! These questions aren’t just a quiz — they’re a smart way to see how current affairs connect with core concepts, just like UPSC asks in the exam.
Each question is based on recent news and backed by clear explanations to help you build strong links between dynamic events and static knowledge.
Today’s topics include: NISAR, chromosphere of the Sun, MiG-21 fighter jets, bleeding eye, CoinDCX, SNIFS, SO₂, Etalin hydropower project, UNFCCC, biostimulants in agriculture, Tyler Prize and more...
Click Here to read the Monthly Current Affairs Pointers (CAP).
QUESTION 1
Regarding the NISAR (NASA-ISRO Synthetic Aperture Radar) mission, consider the following statements:
NISAR is a collaborative Earth observation satellite project between NASA and ISRO.
It is scheduled to be launched onboard the PSLV-C61 and placed into a sun-synchronous orbit.
The satellite is designed to image the entire planet once every 30 days with high-resolution data of Earth’s surface.
It will be the first satellite to employ dual-frequency radar systems for Earth observation.
How many of the above statements are correct?
(a) Only one
(b) Only two
(c) Only three
(d) All four
Answer (b)
Explanation:
Statement 1 is correct: NISAR is a joint initiative between the United States’ NASA and India’s ISRO, aimed at monitoring Earth's land and ice surfaces with advanced radar imaging techniques.
Statement 2 is incorrect: The satellite will not be launched using PSLV-C61. Instead, it is planned to lift off aboard GSLV-F16 and will be positioned in a 734-km sun-synchronous orbit, which allows it to pass over any given point on Earth at the same local solar time.
Statement 3 is incorrect: NISAR will conduct global scans not every 30 days, but every 12 days, offering detailed and recurring radar images of Earth’s features.
Statement 4 is correct: The mission marks a milestone as the first satellite equipped with two radar frequencies — L-band from NASA and S-band from ISRO. These dual frequencies help in capturing diverse surface features and properties such as vegetation, soil moisture, and crustal deformations.
QUESTION 2
With reference to the chromosphere of the Sun, consider the following statements:
The chromosphere is located between the Sun’s outermost atmospheric layer—the million-degree corona—and its visible surface, known as the photosphere.
It is within this layer that dynamic solar phenomena such as solar flares, jets of hot plasma, and intense bursts of energy originate.
Which of the statements above is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer (c)
Explanation:
NASA, in collaboration with a team of international solar physicists, is undertaking a new effort to explore the chromosphere, one of the Sun’s most active and dynamic layers, through a sounding rocket mission launched on July 18 from New Mexico.
The chromosphere appears reddish in color and is strategically positioned between the solar corona (which can reach temperatures of over a million degrees Celsius) and the photosphere, the layer that forms the Sun’s visible surface. Hence, Statement 1 is correct.
It is within this transitional zone—the chromosphere—that several high-energy solar activities originate, including solar flares, hot plasma jets, and intense energy outflows. The region also shows dramatic temperature fluctuations, ranging from around 6,000°C to beyond a million degrees Celsius. Hence, Statement 2 is correct.
The rocket experiment, which will last under ten minutes, will carry the Solar EruptioN Integral Field Spectrograph (SNIFS), a specialized instrument designed to study the Sun’s eruptive activity in this region.
QUESTION 3
With regard to the Indian Air Force’s (IAF) MiG-21 fighter jets, consider the following statements:
The IAF plans to formally retire its remaining fleet of Russian-origin MiG-21s in a ceremonial event scheduled for September 19 at Chandigarh Air Force Station.
Currently, five squadrons of MiG-21 Bison aircraft remain in active service.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer (a)
Explanation:
After over 60 years of service, during which they played a pivotal role in India's aerial defense across multiple military conflicts, the MiG-21 fighter jets are now reaching the end of their operational lifespan.
The Indian Air Force is scheduled to hold a ceremonial farewell for its last MiG-21 fleet on September 19 at the Chandigarh airbase, marking the end of an iconic era in Indian military aviation. Hence, Statement 1 is correct.
At present, only two squadrons of the MiG-21 Bison variant remain in active deployment with the IAF, not five as stated. Hence, Statement 2 is incorrect.
Introduced into IAF service in 1963, India has procured nearly 700 MiG-21 aircraft over the decades in various configurations — including Type-77, Type-96, BIS, and Bison models.
The MiG-21's retirement, initially planned for 2022, was delayed to allow time for the phased induction of newer fighters, notably the indigenous Light Combat Aircraft (LCA) Tejas, which will succeed the MiG-21 in frontline operations.
QUESTION 4
Which of the following viruses is commonly referred to as the "bleeding eye" virus?
(a) Marburg virus
(b) Avian influenza
(c) Hepatitis B virus
(d) Hepatitis E virus
Answer (a)
Explanation:
Marburg virus disease (MVD), often nicknamed the “bleeding eye virus”, is recognized as one of the deadliest viral infections known to affect humans. Mortality rates in past outbreaks have ranged from 24% to 88%, depending on the virus strain involved and the quality of medical intervention provided.
Belonging to the filovirus family, the Marburg virus shares many clinical characteristics with the Ebola virus. Both are capable of causing severe hemorrhagic fevers and can result in highly fatal outbreaks, though such events are relatively rare.
The initial outbreak of MVD was documented in 1967 in Marburg, Germany, which gave the virus its name. Since then, most subsequent outbreaks have occurred in African nations, including Tanzania, Ghana, and most recently Rwanda, where a case was reported in September of the current year.
The World Health Organization (WHO) classifies Marburg virus among the pathogens that pose a critical threat to global health. Currently, no approved vaccines or specific antiviral treatments exist to combat MVD.
QUESTION 5
Among the following, how many are known to be released as by-products during volcanic eruptions?
Sulphur compounds
Helium gas
Argon gas
Pyroclastic debris
(a) Only one
(b) Only two
(c) Only three
(d) All four
Answer (c)
Explanation:
Volcanoes can erupt both on land and beneath the ocean surface. These eruptions release substances that are much hotter than their surroundings, which may include molten rock (called magma while beneath the surface and lava once it emerges), gaseous emissions, and solid fragments.
Magma originates in the upper mantle of the Earth and, as it rises toward or breaches the crust, it transforms into lava. Eruptions may discharge a combination of lava flows, pyroclastic materials (such as volcanic ash, cinders, and bombs), and a variety of gases.
Typical gaseous emissions from volcanic activity include sulphur compounds, nitrogen, and trace amounts of elements like chlorine, hydrogen, and argon. These emissions are common features of volcanic outgassing.
However, helium gas is not a typical component released during volcanic eruptions. It is primarily associated with radioactive decay processes deep within the Earth and is not a standard by-product of magma or lava outflows.
Thus, sulphur compounds, argon, and pyroclastic debris are by-products of volcanic activity.
QUESTION 6
With reference to Europa, one of Jupiter’s moons, consider the following statements:
Statement I: Europa is considered among the top candidates in the search for alien life beyond Earth.
Statement II: Data from the James Webb Space Telescope has revealed the presence of carbon dioxide and crystalline water ice on Europa’s surface, pointing toward recent exposure of material from its subsurface ocean.
Which of the statements is/are correct?
(a) Both Statement I and Statement II are correct, and Statement II correctly explains Statement I
(b) Both Statement I and Statement II are correct, but Statement II does not explain Statement I
(c) Statement I is true, but Statement II is false
(d) Statement I is false, but Statement II is true
Answer (a)
Explanation:
Europa, one of the major moons orbiting Jupiter, is widely viewed as a potential hub for discovering extraterrestrial life. The reason lies in its subsurface ocean, believed to lie beneath a thick icy crust, along with geological activity that could create habitable conditions. Therefore, Statement I is correct.
Recent findings from the James Webb Space Telescope (JWST) have detected crystalline water ice, carbon dioxide, and sodium chloride on Europa’s surface.
These detections were especially notable in regions like Tara Regio, which appear geologically young. This supports the theory that material from the moon’s hidden ocean has recently been transported to the surface, offering insight into its chemical composition. Therefore, Statement II is also correct.
Since the detection of these surface compounds provides direct evidence of potential habitability and supports the theory of subsurface ocean activity, Statement II directly explains the rationale behind Statement I.
QUESTION 7
CoinDCX, which has recently made headlines, is associated with:
(a) A government-led initiative for promoting digital payments
(b) A private space-tech firm collaborating with ISRO
(c) A cryptocurrency trading platform affected by a major security breach
(d) A rural banking solution launched by the Reserve Bank of India
Answer (c)
Explanation:
CoinDCX, a Mumbai-based cryptocurrency exchange, was recently the victim of a major security incident, in which it lost approximately USD 44.2 million.
The breach occurred on July 19, 2025, and involved an exploit targeting one of the platform’s internal operational wallets. Notably, the incident came to light 17 hours later through an alert by well-known blockchain analyst ZachXBT.
This event marks the second large-scale crypto hack in India within a year, intensifying the conversation around the need for enhanced cybersecurity measures and regulatory oversight in the digital asset industry.
QUESTION 8
With regard to NASA's sounding rocket initiative involving SNIFS, consider the following assertions:
The SNIFS instrument has been developed to explore the Sun’s chromosphere — the transitional layer located between the photosphere and the corona.
It captures three-dimensional spectroscopic observations, enabling the collection of a complete spectrum for every individual pixel in its field of view.
The mission includes observation of the Lyman-alpha spectral line of hydrogen, which serves as a vital indicator of the chromosphere’s properties.
SNIFS is designed as a long-term orbital satellite platform, expected to function over a span of several years.
Which of the above statements are correct?
(a) 1 and 2 only
(b) 1, 2 and 3 only
(c) 2, 3 and 4 only
(d) 1, 2, 3 and 4
Answer (b)
Explanation:
Statement 1 is correct: The Solar EruptioN Integral Field Spectrograph (SNIFS) is intended to investigate the Sun’s chromosphere — a dynamic atmospheric layer situated between the visible surface (photosphere) and the outermost region (corona).
Statement 2 is correct: SNIFS is pioneering in its category as the first ultraviolet integral field spectrograph designed for solar science. It delivers three-dimensional spectroscopic datasets, where each image pixel is associated with a full ultraviolet spectrum.
Statement 3 is correct: One of SNIFS’ major observational targets is the Lyman-α line of hydrogen — the brightest spectral line in the Sun’s ultraviolet output — offering critical insights into the temperature, motion, and density of the chromospheric layer.
Statement 4 is incorrect: SNIFS is not an orbital satellite but rather a suborbital payload aboard a sounding rocket. Its total operational window is extremely brief — under 10 minutes — as it performs observations during a single high-altitude flight.
QUESTION 9
Examine the following statements regarding air pollutants and their health/environmental effects:
Sulphur dioxide (SO₂), upon entering the atmosphere, primarily reacts with oxygen to form ammonium sulfate.
Prolonged exposure to particulate matter smaller than 2.5 microns (PM2.5) may result in chronic health conditions.
High levels of SO₂ exposure can elevate the risk of cardiovascular events such as heart attacks.
Carbon monoxide (CO) is one of the gases responsible for acid rain formation.
How many of the above statements are correct?
(a) Only one
(b) Only two
(c) Only three
(d) All four
Answer (b)
Explanation:
Statement 1 is incorrect: Sulphur dioxide (SO₂), when emitted into the atmosphere, reacts not with oxygen but mainly with ammonia (NH₃) to form ammonium sulfate. This compound significantly contributes to PM2.5 air pollution in India — according to findings from the Centre for Research on Energy and Clean Air (CREA). Thus, the reaction cited in the statement is scientifically incorrect.
Statement 2 is correct: Fine particulate matter (PM2.5) is a serious public health concern. Its small size allows it to penetrate deep into the lungs and bloodstream, leading to chronic conditions such as asthma, bronchitis, cardiovascular diseases, and other long-term respiratory issues.
Statement 3 is correct: Short-term or direct exposure to elevated concentrations of SO₂ can lead to irritation of the respiratory system. Long-term exposure has been linked with heart attacks, stroke, and an increased risk of premature death, as highlighted in recent environmental health assessments.
Statement 4 is incorrect: Carbon monoxide (CO) is a toxic gas that interferes with the blood’s oxygen-carrying capacity but does not participate in acid rain formation. Acid rain is primarily caused by sulphur dioxide (SO₂) and nitrogen oxides (NOₓ), which form sulfuric and nitric acids upon interaction with water vapor in the atmosphere.
QUESTION 10
Review the following statements related to India’s energy sector:
India has set a target of achieving 500 GW of non-fossil fuel-based power generation capacity by the year 2040.
At present, India operates more than 10 nuclear reactors.
In the year 2024, India added nearly 10 GW of renewable energy capacity, marking a decline compared to the additions made in 2023.
Which of the above statements are correct?
(a) 1 and 2 only
(b) 2 only
(c) 1, 2 and 3
(d) 3 only
Answer (b)
Explanation:
Statement 1 is incorrect: India’s actual goal is to install 500 gigawatts of non-fossil fuel-based electricity capacity by 2030, not by 2040. This target is a key part of India's climate and energy transition commitments.
Statement 2 is correct: India currently operates 22 nuclear reactors with a total installed capacity of 6,780 megawatts electric (MWe). Among them, 18 are Pressurised Heavy Water Reactors (PHWRs), and 4 are Light Water Reactors (LWRs). These figures clearly indicate that India has significantly more than 10 active nuclear reactors.
Statement 3 is incorrect: Contrary to what is suggested, India added nearly 30 GW of renewable energy capacity in 2024, which is the highest in any single year so far. Of this, solar power accounted for around 24 GW, marking a strong performance compared to 2023. Thus, the claim that only 10 GW was installed and that this represented a decline is factually wrong.
QUESTION 11
Karewa formations are primarily found in which of the following regions?
(a) Valley of Flowers
(b) Western Ghats
(c) Patkai Range
(d) Kashmir Valley
Answer (d)
Explanation:
Recent research indicates that the natural uplift of the Pir Panjal range approximately four million years ago played a crucial role in shaping the present-day Mediterranean-like climate of the Kashmir Valley. Often called the “Switzerland of the East,” Kashmir experiences warm summers and cold, rainy winters.
The key source of groundwater and replenishment of water bodies in this valley comes from snow and rainfall during the winter months, which are linked to the passage of western disturbances. The peak of winter typically falls between mid-December and January.
The elevation of the Pir Panjal range, part of the Lesser Himalayas, acts as an orographic barrier that blocks the moisture-rich summer monsoon winds from entering the valley. This has resulted in the unique Mediterranean climatic conditions observed in the region.
Scientists from the Birbal Sahni Institute of Palaeosciences (BSIP) alongside researchers from the University of Kashmir’s Earth Sciences Department reconstructed the valley’s ancient climate history by studying leaf fossils extracted from the Karewa formations. These Karewa formations are distinct elevated tablelands found specifically in the Kashmir Valley.
QUESTION 12
With reference to the proposed Etalin hydropower project in the Dibang Valley, which of the following statements are correct?
It is planned as a run-of-the-river project on the Dri and Talo rivers.
The project will be located in Assam.
It is based on the Teesta River.
How many of the above statements are correct?
(a) Only one
(b) Only two
(c) All three
(d) None
Answer (a)
Explanation:
An expert panel under the Union Environment Ministry is expected to soon review the environmental clearance for the 3,087 MW Etalin hydropower project situated in the Dibang Valley of Arunachal Pradesh.
This development comes shortly after China began work on the world’s largest hydroelectric project, with a capacity of 60 gigawatts, on the Yarlung Zangbo River upstream from India. Consequently, statements 2 and 3 are incorrect since the Etalin project is neither in Assam nor linked to the Teesta River.
The Etalin project is designed as a run-of-the-river scheme on the Dri and Talo rivers, which involves building concrete gravity dams to divert the river flow through two separate channels. Run-of-the-river projects typically have minimal or no reservoir storage. Thus, statement 1 is correct.
The Dri and Talo rivers are tributaries of the Dibang River, which eventually merges into the Brahmaputra basin. China’s hydropower initiatives on the Yarlung Zangbo (Brahmaputra) have raised concerns about potential impacts on downstream water availability and security in India.
QUESTION 13
Regarding the Pradhan Mantri Matsya Sampada Yojana (PMMSY), consider the following statements:
The scheme was introduced by the Ministry of Fisheries, Animal Husbandry, and Dairying in 2016.
It aims to boost aquaculture productivity and enhance fisheries management.
Which of the above statements is/are correct?
(a) Only 1
(b) Only 2
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer (b)
Explanation:
In the face of stagnant incomes from traditional wheat-paddy cropping cycles and rising inflation, many farmers in Punjab have diversified into fish farming alongside their conventional agricultural practices, resulting in substantial benefits. Over the last five years, fish farming, once regarded as a minor occupation in Punjab, has evolved into a significant agricultural diversification strategy and a lucrative source of livelihood for numerous farmers.
Supporting this transition, the Government of India launched the Pradhan Mantri Matsya Sampada Yojana (PMMSY) in 2020, offering subsidies to boost fish production. Since 2020-21, Punjab’s fish output has grown by over 35,000 tonnes, valued around Rs 500 crore. The total fish production in the state now exceeds 2 lakh tonnes, worth approximately Rs 2,600 to Rs 3,000 crore.
The PMMSY, initiated in May 2020, represents a comprehensive initiative to modernize and transform India’s fisheries sector. Therefore, statement 1 is incorrect.
The scheme’s core objectives include enhancing aquaculture productivity, improving fisheries management, generating employment opportunities—targeting 55 lakh new jobs—and developing infrastructure such as five integrated aquaparks. Hence, statement 2 is correct.
Further aims of the PMMSY include doubling fisheries exports to Rs 1 lakh crore and increasing aquaculture productivity from 3 to 5 tonnes per hectare. The scheme also emphasizes improving fish farming infrastructure, minimizing seafood waste, and promoting sustainable practices to ensure environmental protection while expanding the sector.
QUESTION 14
With regard to the United Nations Framework Convention on Climate Change (UNFCCC) secretariat, consider the following statements:
The UNFCCC secretariat was created in 1992 and is presently headquartered in Geneva, Switzerland.
It facilitates the implementation of the UNFCCC, the Kyoto Protocol, and the Paris Agreement.
It is responsible for maintaining the registry of Nationally Determined Contributions (NDCs) under the Paris Agreement.
Its work is limited to collaboration with governments and excludes engagement with non-Party actors such as businesses and civil society organizations.
Which of the above statements is/are correct?
(a) 1 and 2 only
(b) 3 and 4 only
(c) 2 and 3 only
(d) 2, 3, and 4 only
Answer (c)
Explanation:
The UNFCCC secretariat was established in 1992, but its current headquarters is in Bonn, Germany, having relocated from Geneva in 1996. Therefore, statement 1 is incorrect.
The secretariat actively supports the execution of the UNFCCC itself, along with the Kyoto Protocol and the Paris Agreement. Hence, statement 2 is correct.
One of the secretariat’s key roles is maintaining the official registry for Nationally Determined Contributions (NDCs), which is a foundational element of the Paris Agreement’s framework. Hence, statement 3 is correct.
Contrary to statement 4, the secretariat also engages with a wide range of non-Party stakeholders—including businesses, urban localities, and civil society groups—through initiatives such as the Marrakech Partnership for Global Climate Action and various regional Climate Weeks. Hence, statement 4 is incorrect.
QUESTION 15
With regard to biostimulants in agriculture, consider the following statements:
Biostimulants supply essential nutrients such as nitrogen, phosphorus, and potassium directly to plants.
They aid in enhancing plant growth, increasing yield, and boosting tolerance to stress.
Biostimulants are currently governed under the Fertiliser (Control) Order, 1985.
Which of the above statements is/are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer (b)
Explanation:
Biostimulants consist of substances or living microorganisms that activate natural physiological processes in plants, thereby improving nutrient absorption, growth, yield, and the ability to withstand various stresses. Therefore, statement 2 is correct.
Unlike conventional fertilizers that directly provide essential nutrients like nitrogen, phosphorus, and potassium (NPK), biostimulants do not act as a direct nutrient source; instead, they enhance the plant’s biological functions. Hence, statement 1 is incorrect.
Recently, biostimulants have been brought under the regulatory framework of the Fertiliser (Control) Order, 1985, which means they are now legally managed alongside fertilizers. Hence, statement 3 is correct.
QUESTION 16
Who was honored with the Tyler Prize for Environmental Achievement in 2025?(a) Madhav Gadgil
(b) Rashid Sumaila
(c) Gretchen C. Daily and Pavan Sukhdev
(d) Sandra Díaz and Eduardo Brondízio
Answer (d)
Explanation:
In 2025, the Tyler Prize for Environmental Achievement was awarded to Sandra Díaz and Eduardo Brondízio.
As detailed on tylerprize.org, the Tyler Prize is regarded as the world’s most prestigious annual environmental award. Often called the “green Nobel Prize,” it was the first prize dedicated exclusively to environmental science and achievements. The prize is administered by the University of Southern California, based in Los Angeles, USA.
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