UPSC CSE Prelims
Science & Technology Previous Year Questions (PYQs)
Solved Previous Year Questions (PYQs) for Science & Technology in UPSC CSE Prelims in English & Hindi Medium.
Chapter Breakdown: Scroll →
Organic Light Emitting Diodes (OLEDs) are used to create the digital display in many devices. What are the advantages of OLED displays over Liquid Crystal displays?
- OLED displays can be fabricated on flexible plastic substrates.
- Roll-up displays embedded in clothing can be made using OLEDs.
- Transparent displays are possible using OLEDs.
Select the correct answer using the code given below
Detailed Explanation:
Answer: Option 3 — 1, 2 and 3
✅ Statement 1 – Correct: OLEDs use thin films of organic compounds that can be deposited on flexible plastic or metal foil substrates, unlike LCDs which require rigid glass panels. This enables bendable and foldable displays.
✅ Statement 2 – Correct: The inherent flexibility of OLED technology allows fabrication of roll-up displays that can be embedded in clothing, wearables, and other flexible surfaces—applications impossible with rigid LCD technology.
✅ Statement 3 – Correct: OLED pixels emit light independently without requiring a backlight, and the organic layers can be made semi-transparent. This enables creation of transparent displays where the screen is see-through when not displaying content, unlike LCDs which are always opaque due to their backlight and liquid crystal structure.
All three statements correctly identify key advantages of OLED over LCD technology.
In India, it is legally mandatory for which of the following to report on cybersecurity incidents?
- Service providers
- Data centres
- Body corporate
Select the correct answer using the code given below:
Detailed Explanation:
Answer: Option 4 — 1, 2 and 3
✅ Statement 1 – Correct: Service providers are legally mandated to report cybersecurity incidents to CERT-In (Indian Computer Emergency Response Team) under Section 70B of the Information Technology Act, 2000, and the Information Technology (The Indian Computer Emergency Response Team and Manner of Performing Functions and Duties) Rules, 2013.
✅ Statement 2 – Correct: Data centres are explicitly listed among the entities required to mandatorily report cybersecurity incidents to CERT-In under the IT (CERT-In) Rules, 2013. This includes incidents like data breaches, unauthorized access, and system compromises within six hours of noticing or being brought to notice.
✅ Statement 3 – Correct: Body corporates (companies and organizations) are required to report specified cybersecurity incidents to CERT-In under the IT Act, 2000, and associated rules. This obligation ensures timely response to cyber threats affecting business operations and sensitive data.
Consider the following statements:
- In tropical regions, Zika virus disease is transmitted by the same mosquito that transmits dengue.
- Sexual transmission of Zika virus disease is possible.
Which of the statements given above is/are correct?
Detailed Explanation:
Answer: Option 3 — Both 1 and 2
✅ Statement 1 – Correct: Zika virus is primarily transmitted by the Aedes aegypti mosquito in tropical regions. This is the same mosquito species that transmits dengue, chikungunya, and yellow fever. The mosquito becomes infected when it bites an infected person and can then transmit the virus to other people through subsequent bites.
✅ Statement 2 – Correct: Sexual transmission of Zika virus is well-documented and possible. The virus can be transmitted through vaginal, anal, and oral sex. It can persist in semen for several months, making sexual transmission a significant route of infection even in areas without active mosquito transmission. Pregnant women are particularly at risk as Zika can cause severe birth defects.
Therefore, both statements are correct.
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The terms ‘Event Horizon’, ‘Singularity’, `String Theory’ and ‘Standard Model’ are sometimes seen in the news in the context of
Detailed Explanation:
Answer: Option 1 — Observation and understanding of the Universe
All four terms are fundamental concepts in cosmology and theoretical physics. Event Horizon is the boundary around a black hole beyond which nothing can escape its gravitational pull. Singularity refers to a point of infinite density and gravity, such as at the center of a black hole or the initial state of the Big Bang. String Theory is a theoretical framework attempting to unify all fundamental forces of nature by describing particles as vibrating strings. Standard Model is the established theory in particle physics describing fundamental particles and three of the four forces (excluding gravity). These concepts are central to understanding the structure, origin, and evolution of the Universe, making Option 1 the correct answer.
With reference to ‘National Intellectual Property Rights Policy’, consider the following statements:
- It reiterates India’s commitment to the Doha Development Agenda and the TRIPS Agreement.
- Department of Industrial Policy and Promotion is the nodal agency for regulating intellectual property rights in India.
Which of the above statements is/are correct?
Detailed Explanation:
Answer: Option 3 — Both 1 and 2
The National Intellectual Property Rights Policy, adopted in 2016, explicitly reiterates India's commitment to international IPR frameworks including the TRIPS Agreement and the Doha Development Agenda, which provides flexibilities for developing nations. The Department for Promotion of Industry and Internal Trade (DPIIT), formerly known as the Department of Industrial Policy and Promotion, serves as the nodal agency for IPR policy formulation and implementation in India.
✅ Statement 1 – Correct: The National IPR Policy reiterates India's commitment to the Doha Development Agenda and the TRIPS Agreement, ensuring access to flexibilities like compulsory licensing for affordable medicines.
✅ Statement 2 – Correct: The Department of Industrial Policy and Promotion (now DPIIT) under the Ministry of Commerce and Industry is indeed the nodal agency for regulating and implementing IPR policy in India.
Which one of the following is the best description of ‘INS Astradharini’, that was in the news recently?
Detailed Explanation:
Answer: Option 3 — Torpedo launch and recovery vessel
INS Astradharini is India's first indigenously designed and built Torpedo Launch and Recovery Vessel (TLRV), commissioned in 2015 with 95% indigenous content.
It serves as a specialized platform for technical trials of underwater weapons like torpedoes and mines developed by NSTL, featuring a catamaran hull design for enhanced stability during weapon recovery operations.
What is ‘Greased Lightning-10 (GL-10)’, recently in the news?
Detailed Explanation:
Answer: Option 1 — Electric plane tested by NASA
Greased Lightning-10 (GL-10) is an experimental hybrid-electric aircraft developed by NASA to test distributed electric propulsion and vertical take-off and landing (VTOL) capabilities.
The GL-10 is a subscale, remotely-piloted aircraft that can take off like a helicopter and transition to fixed-wing flight, demonstrating future applications in unmanned cargo transport and surveillance.
Which of the following statements is/are correct? Viruses can infect -
- Bacteria
- Fungi
- Plants
Detailed Explanation:
Answer: Option 4 — 1, 2 and 3
✅ Statement 1 – Correct: Bacteriophages (phages) are viruses that infect bacteria by injecting their genetic material into bacterial cells.
✅ Statement 2 – Correct: Mycoviruses are viruses that specifically infect fungi, often causing latent infections without visible symptoms.
✅ Statement 3 – Correct: Plant viruses infect various plant species by hijacking cellular machinery, causing diseases like mosaic patterns and stunted growth.
With reference to ‘Astrosat’, the astronomical observatory launched by India, which of the following statements is/are correct?
- Other than the USA and Russia, India is the only country to have launched a similar observatory into space.
- Astrosat is a 2000 kg satellite placed in an orbit at 1650 km above the surface of the Earth.
Detailed Explanation:
Answer: Option 4 — Neither 1 nor 2
❌ Statement 1 – Incorrect: India is the 5th country to launch a space observatory, not the 3rd. USA, Russia, Japan, and Europe (ESA) had already launched similar observatories before AstroSat.
❌ Statement 2 – Incorrect: AstroSat has a mass of approximately 1513 kg (not 2000 kg) and was placed in a 650 km orbit (not 1650 km) above Earth's surface by PSLV-C30 in September 2015.
India is an important member of the ‘International Thermonuclear Experimental Reactor’. If this experiment succeeds, what is the immediate advantage for India?
Detailed Explanation:
Answer: Option 4 — It can build fusion reactors for power generation
ITER (International Thermonuclear Experimental Reactor) is a collaborative project to demonstrate nuclear fusion as a viable energy source by merging hydrogen isotopes at extremely high temperatures.
India's participation provides access to fusion technology, research expertise, and engineering know-how needed to eventually build its own fusion reactors for clean, abundant power generation.
Why other options are incorrect:
• Option 1: Thorium utilization relates to advanced fission reactors, not fusion technology
• Option 2: Satellite navigation involves space technology (NAVIC/IRNSS), unrelated to ITER
• Option 3: ITER focuses on fusion, not improving existing fission reactor efficiency
With reference to ‘Bitcoins’ sometimes seen in the news, which of the following statements is/are correct?
- Bitcoins are tracked by the Central Banks of the countries.
- Anyone with a Bitcoin address can send and receive Bitcoins from anyone else with a Bitcoin address.
- Online payments can be sent without either side knowing the identity of the other.
Select the correct answer using the code given below.
Detailed Explanation:
Answer: Option 2 — 2 and 3 only
❌ Statement 1 – Incorrect: Bitcoins are not tracked by Central Banks. Bitcoin operates on a decentralized blockchain network without central authority oversight. Central Banks do not maintain or monitor Bitcoin transactions.
✅ Statement 2 – Correct: Anyone with a Bitcoin address can send and receive Bitcoins from anyone else with a Bitcoin address. No intermediary or bank approval is required for peer-to-peer transactions.
✅ Statement 3 – Correct: Online payments can be sent without either side knowing the identity of the other. Bitcoin addresses are pseudonymous—only the addresses appear on the blockchain, not the real identities of users.
With reference to ‘LiFi’, recently in the news, which of the following statements is/are correct?
- It uses light as the medium for high-speed data transmission.
- It is a wireless technology and is many times faster than ‘WiFi’.
Detailed Explanation:
Answer: Option 3 — Both 1 and 2
✅ Statement 1 – Correct: LiFi (Light Fidelity) uses visible light waves from LED bulbs for high-speed data transmission through rapid flickering invisible to human eyes.
✅ Statement 2 – Correct: LiFi is a wireless technology with theoretical speeds exceeding 100 Gbps, significantly faster than WiFi's current maximum of 11 Gbps.
Why does the Government of India promote the use of ‘Neem-coated Urea’ in agriculture?
Detailed Explanation:
✅ Statement 2 – Correct: Neem coating acts as a nitrification inhibitor, slowing down the conversion of urea to nitrate, thereby reducing nitrogen losses through leaching, volatilization and denitrification, and ensuring gradual nitrogen release for better crop uptake.
❌ Statement 1 – Incorrect: Neem coating does not enhance nitrogen fixation by soil microorganisms; it primarily inhibits nitrification.
❌ Statement 3 – Incorrect: While neem-coated urea reduces nitrous oxide emissions by minimizing denitrification, it does not eliminate greenhouse gas release completely.
❌ Statement 4 – Incorrect: Neem-coated urea is not a weedicide-fertilizer combination; neem acts as a nitrification inhibitor, not a weedicide.
‘Project Loon’, sometimes seen in the news, is related to -
Detailed Explanation:
Project Loon was a Google initiative that used high-altitude balloons in the stratosphere to provide internet connectivity to remote and underserved areas, functioning as floating cell towers.
The project was discontinued in January 2021 due to commercial viability challenges, despite its technological success in delivering wireless internet access.
Regarding ‘DigiLocker’, sometimes seen in the news, which of the following statements is/are correct?
- It is a digital locker system offered by the Government under Digital India Programme.
- It allows you to access your e-documents irrespective of your physical location.
Select the correct answer using the code given below
Detailed Explanation:
✅ Statement 1 – Correct: DigiLocker is a cloud-based digital locker system launched by the Government of India under the Digital India Programme in 2015 to provide secure storage for e-documents and reduce reliance on physical documents.
✅ Statement 2 – Correct: DigiLocker allows users to access their e-documents from anywhere using internet connectivity, eliminating the need to carry physical documents.