UPSC 2024: Nexus 31—40

Space Tech, Stellar Physics, Advanced Materials & Financial Markets. [Set A]

Question 31

Space Technology

With reference to radioisotope thermoelectric generators (RTGs), consider the following statements:

RTGs are miniature fission reactors.
RTGs are used for powering the onboard systems of spacecrafts.
RTGs can use Plutonium-238, which is a by-product of weapons development.

Which of the statements given above are correct?

Official Verdict: (b) 2 and 3 only

The Core Concept: Radioisotope Thermoelectric Generators (RTGs) are not fission reactors (1 is false). Instead of splitting atoms in a chain reaction, they simply harvest the natural heat released by the passive radioactive decay of isotopes—primarily Plutonium-238 (a non-weapons-grade isotope synthesized as a by-product of nuclear development) (3 is true). Because they have no moving parts and run for decades without sunlight, RTGs are the gold standard for powering deep-space probes like Voyager, Cassini, and the Curiosity rover (2 is true).

Tethered to: REALM 355: Launch Vehicles & Applications

Question 32

Astrophysics

Consider the following statements:

Statement-I:

Giant stars live much longer than dwarf stars.

Statement-II:

Compared to dwarf stars, giant stars have a greater rate of nuclear reactions.

Which one of the following is correct in respect of the above statements?

Official Verdict: (d) Statement-I is incorrect, but Statement-II is correct

The Core Concept: Stellar lifespans are counter-intuitive. A massive Giant Star has immense gravitational pressure crushing its core, which forces it to fuse hydrogen at an incredibly violent and rapid rate (Statement-II is true). Because of this voracious high rate of nuclear reactions, Giant Stars burn through their massive fuel supplies very quickly (millions of years) and die in supernovae. In contrast, low-mass dwarf stars (like red dwarfs) fuse hydrogen at a slow, frugal trickle, allowing them to live for trillions of years. Therefore, giants live much shorter lives than dwarfs (Statement-I is false).

Tethered to: REALM 106: Stars & Stellar Evolution

Question 33

Human Physiology

Which one of the following is synthesised in human body that dilates blood vessels and increases blood flow?

(a) Nitric oxide
(b) Nitrous oxide
(c) Nitrogen dioxide
(d) Nitrogen pentoxide

Official Verdict: (a) Nitric oxide

The Core Concept: Nitric Oxide (NO) is a critical signaling molecule naturally synthesized by the endothelium (inner lining) of blood vessels. It signals the surrounding smooth muscle to relax, leading to vasodilation (widening of blood vessels), which lowers blood pressure and increases blood flow. (This discovery won the 1998 Nobel Prize in Medicine and is the functional pathway for drugs like Nitroglycerin and Viagra). Nitrous oxide ($N_2O$) is "laughing gas," and Nitrogen dioxide ($NO_2$) is a toxic air pollutant.

Tethered to: REALM 185: Circulatory, Blood & Heart

Question 34

Electromagnetic Technologies

Consider the following activities:

Identification of narcotics on passengers at airports or in aircraft
Monitoring of precipitation
Tracking the migration of animals

In how many of the above activities can the radars be used?

Official Verdict: (b) Only two

The Core Concept: Radar (Radio Detection and Ranging) uses radio waves to determine distance, angle, or velocity of objects. Doppler Weather Radars are extensively used to monitor precipitation and storms (2 is true). Specialized Avian Radars are used heavily by airports and ornithologists to track bird/animal migrations to prevent bird strikes (3 is true). However, identifying specific chemical compositions like narcotics requires chemical analysis (Ion Mobility Spectrometry) or density penetration (Backscatter X-Rays), not standard macro-object radar tracing (1 is false). Thus, only two apply.

Tethered to: REALM 96: Lenses, Instruments & Lasers

Question 35

Defence Technology

Consider the following aircraft:

Rafael
MiG-29
Tejas MK-1

How many of the above are considered fifth generation fighter aircraft?

Official Verdict: (d) None

The Core Concept: A 5th-generation fighter is characterized by highly advanced stealth capabilities (internal weapon bays, radar-absorbent materials) and supercruise (e.g., US F-22/F-35, Russian Su-57, Chinese J-20). The Dassault Rafale is a highly advanced 4.5 generation "omnirole" fighter. The Russian MiG-29 is a legacy 4th generation fighter. India's indigenous HAL Tejas Mk-1 is a 4th/4.5 generation light combat aircraft. None of the listed aircraft are 5th generation.

Tethered to: REALM 435: Submarines, Carriers & Aircraft

Question 36

Biomedical Polymers

In which of the following are hydrogels used?

Controlled drug delivery in patients
Mobile air-conditioning systems
Preparation of industrial lubricants

Select the correct answer using the code given below:

Official Verdict: (a) 1 only

The Core Concept: Hydrogels are highly absorbent, 3D cross-linked hydrophilic polymer networks. Because they are highly biocompatible and can safely absorb/retain large amounts of water (or biological fluids) without dissolving, they are revolutionary in medicine for contact lenses, wound dressings, and controlled drug delivery systems (1 is true). Air conditioning systems rely on volatile chemical refrigerants (like HFCs), not hydrogels (2 is false). Heavy industrial machinery requires hydrophobic petroleum/synthetic oils or greases as lubricants to reduce friction, not water-absorbing hydrogels (3 is false).

Tethered to: REALM 328: Formulations & Delivery Systems

Question 37

Clean Energy Transport

Which one of the following is the exhaust pipe emission from Fuel Cell Electric Vehicles, powered by hydrogen?

(a) Hydrogen peroxide
(b) Hydronium
(c) Oxygen
(d) Water vapour

Official Verdict: (d) Water vapour

The Core Concept: A Hydrogen Fuel Cell Electric Vehicle (FCEV) operates cleanly without combustion. Inside the fuel cell, pressurized Hydrogen gas ($H_2$) from the tank reacts electrochemically with Oxygen ($O_2$) drawn from the outside air across an electrolyte membrane. This reaction produces the electricity that drives the motor, and the only chemical byproduct expelled from the exhaust pipe is pure $H_2O$ (Water Vapour / Water).

Tethered to: REALM 78: Hydrogen & Emerging Tech

Question 38

Renewable Energy Infrastructure

Recently, the term "pumped-storage hydropower" is actually and appropriately discussed in the context of which one of the following?

(a) Irrigation of terraced crop fields
(b) Lift irrigation of cereal crops
(c) Long duration energy storage
(d) Rainwater harvesting system

Official Verdict: (c) Long duration energy storage

The Core Concept: Pumped-storage hydropower is effectively a massive, gravitational "water battery." During periods of low electricity demand (like nighttime) or surplus renewable generation, excess grid energy is used to pump water from a lower elevation reservoir to a higher elevation reservoir. When demand spikes, the water is released back down through turbines to generate electricity. It is the most established technology for utility-scale, long-duration energy storage.

Tethered to: REALM 72: Hydro-Electric Power

Question 39

Environmental Engineering

"Membrane Bioreactors" are often discussed in the context of:

(a) Assisted reproductive technologies
(b) Drug delivery nanotechnologies
(c) Vaccine production technologies
(d) Wastewater treatment technologies

Official Verdict: (d) Wastewater treatment technologies

The Core Concept: A Membrane Bioreactor (MBR) is an advanced technology used specifically for municipal and industrial wastewater treatment. It ingeniously combines a traditional biological treatment process (where microbes eat the organic sewage waste) with advanced microfiltration or ultrafiltration membranes. The membrane filters out the suspended solids and bacteria, yielding exceptionally high-quality effluent water suitable for recycling or discharge.

Tethered to: REALM 52: Water Conservation & Mgt

Question 40

Financial Instruments

With reference to the Indian economy, "Collateral Borrowing and Lending Obligations" are the instruments of:

(a) Bond market
(b) Forex market
(c) Money market
(d) Stock market

Official Verdict: (c) Money market

The Core Concept: Financial markets are broadly divided by time horizons. The Capital Market (stocks and long-term bonds) handles investments exceeding one year. The Money Market handles short-term liquidity (from overnight up to 365 days). Collateralized Borrowing and Lending Obligations (CBLO) were created by the Clearing Corporation of India (CCIL) as a highly secure, short-term money market instrument allowing banks, mutual funds, and primary dealers to borrow and lend cash for periods up to one year, utilizing Government Securities as collateral. (Note: CBLO was technically phased out in 2018 and replaced by Triparty Repo / TREPS, but the underlying money-market concept remains identical).

Tethered to: REALM 122: Financial Markets