UPSC Prelims 2025 Analysis

Explanation

Viruses can survive in oceans, infect bacteria, and alter host cell transcription.

❌Statement I: False. Viruses can survive in ocean waters, and marine viruses are highly abundant.

❌Statement II: False. Viruses can infect bacteria; for example, bacteriophages specifically infect bacteria.

❌Statement III: False. Viruses can alter host transcription and modify host gene expression.

None of the statements are correct.

Explanation

In lithium-ion batteries, the cathode is typically made of materials that include Cobalt, Lithium, and Nickel, depending on the chemistry used.

• ✅I. Cobalt: Used in cathodes like LCO and NMC.
• ❌ II. Graphite: Used in the anode, not the cathode.
• ✅III. Lithium: Core element in cathode materials (like LCO, LFP).
• ✅IV. Nickel: Found in cathode types like NMC and NCA.

Three of the four are used in cathodes.

Alternatively, you can use mnemonic CoLiNi to remember Cathode forming materials.

Explanation

✅ Pair I: Dornier-228 : Maritime patrol aircraft — Correct Dornier-228 is used by Indian Navy & Coast Guard for maritime patrol and surveillance.

❌ Pair II: IL-76 : Supersonic combat aircraft — Incorrect IL-76 is a heavy military transport aircraft, not supersonic or combat.

✅ Pair III: C-17 Globemaster III : Military transport aircraft — Correct C-17 is a strategic military transport aircraft used by the Indian Air Force.

Therefore, only pairs I and III are correct.

Explanation

CL-20, HMX, and LLM-105 are chemical substances known for their use as high-energy explosives in military weapons.

• ✅CL-20: A powerful explosive with high energy density.
• ✅ HMX: A well-known military explosive used in various munitions.
• ✅ LLM-105: A newer explosive with similar high performance.

All three are explosives used in military weapons.

Explanation

Coal gasification produces syngas (carbon monoxide + hydrogen), which is a starting point for making many chemicals.

✅I. Ethanol – Syngas can be converted into ethanol using chemical processes. ✅II. Nitroglycerine – Though not made directly, syngas helps produce chemicals (like hydrogen and methanol) needed to make nitroglycerine. ✅III. Urea – Syngas is used to produce ammonia, a key ingredient for urea production.

All three substances can be produced using coal gasification technology.

Explanation

❌ Statement I: Incorrect The National Rail Plan targets 2030 for a future-ready railway, not 2028.

❌ Statement II: Incorrect Kavach is an indigenous Automatic Train Protection system developed under 'Make in India', not with Germany.

✅ Statement III: Correct Kavach uses RFID tags on tracks in station sections to track train location and speed continuously.

Therefore, Statements I and II are incorrect, and Statement III is correct.

Explanation

Majorana 1 chip is linked to quantum computing and deep learning is part of machine learning, but AWS did not introduce the Majorana 1 chip.

• ✅ I. Majorana 1 chip – Expected to advance quantum computing.
• ❌ II. AWS introducing Majorana 1 – Incorrect, it’s a Microsoft project.
• ✅III. Deep learning – A subset of machine learning.

Only statements I and III are correct.

Explanation

Monoclonal antibodies are lab-made proteins that target specific antigens and can be used to treat viral infections like Nipah virus.

• ✅ I. Man-made proteins – Created by cloning a single immune cell type.
• ✅II. Bind to specific antigens – Help stimulate or guide immune response.
• ✅III. Used in viral infections – Applied in treating infections like Nipah virus.

All three statements are correct.

Explanation

✅ Statement I: Correct GAGAN is an Indian SBAS developed by ISRO and AAI to enhance GPS accuracy and integrity, crucial for aviation safety.

✅ Statement II: Correct It improves GPS reliability and accuracy, enabling better air traffic management and safer, efficient navigation.

❌ Statement III: Incorrect GAGAN’s benefits extend beyond aviation to railways, roadways, maritime, agriculture, and disaster management.

Correct Answer: Only Statements I and II are correct.

Explanation

Alternative powertrain vehicles are those that do not use conventional petrol/diesel engines. Instead, they rely on clean energy sources like electricity or hydrogen.

• ✅ I. BEVs – Run fully on batteries and electric motors.
• ✅II. FCEVs – Use hydrogen to make electricity via a fuel cell.
• ✅III. FCEHVs – Combine hydrogen fuel cell + battery + electric motor.

All three are alternatives to traditional fuel vehicles.

Explanation

✅ Statement I: Correct Rare earth elements like europium, terbium, and yttrium are essential in flat TV screens and monitors due to their role in producing vibrant colors and enhancing display quality.

✅ Statement II: Correct These elements exhibit phosphorescence—absorbing energy and slowly emitting light—which is key to their use in color reproduction and brightness in displays.

Relationship: Statement II explains why rare earth elements are crucial in displays, confirming the reason behind Statement I.

Therefore, both statements are correct and related.

Explanation

Unmanned Aerial Vehicles (UAVs) are aircraft systems operated without a human pilot onboard. Their capabilities depend on design type (like fixed-wing, multirotor, or hybrid) and power source.

❌ I. Vertical landing – Only VTOL and multirotor drones can do vertical landings. Fixed-wing UAVs cannot. ❌II. Automated hovering – Only multirotor drones and advanced hybrids can hover. Fixed-wing UAVs cannot hover at all. ❌ III. Battery-only power – Not all UAVs use batteries. Larger ones may use fuel, hybrid, or solar power.

None of the statements are correct.

Explanation

✅ I. Axiom-4: Correct Axiom-4 is a private crewed ISS mission focused on micro-gravity research through scientific experiments.

✅ II. SpaDeX: Correct SpaDeX, ISRO’s autonomous docking tech demo, also supports micro-gravity research during its mission.

✅ III. Gaganyaan: Correct India’s first human spaceflight, Gaganyaan, promotes micro-gravity research by enabling experiments in space.

Therefore, all three missions support and encourage micro-gravity research.