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Home » UPSC Prelims Quiz » UPSC Prelims Quiz: January 24, 2026

UPSC Prelims Quiz: January 24, 2026

Q1. Assertion (A): Nature-based Solutions represent a shift from conservation as an ecological goal to conservation as a systemic risk-management strategy.
Reason (R): NbS frameworks link ecosystem degradation with fiscal instability, climate vulnerability, and long-term economic risk.

Which one of the following is correct?

(a)

Both A and R are correct and R explains A

(b)

Both A and R are correct but R does not explain A

(c)

A is correct but R is incorrect

(d)

A is incorrect but R is correct

Explanation

Assertion – Correct: Nature-based Solutions treat ecosystems as instruments of climate resilience, economic stability and disaster risk reduction, not merely as conservation targets.

Reason – Correct: Ecosystem degradation is linked with fiscal stress, climate vulnerability and economic losses, which is why NbS is framed as a risk-management strategy.

Link: The Reason correctly explains why NbS represents a paradigm shift from traditional conservation.

Answer: (a)
Q2. Which one of the following best explains why the same decarbonisation sequence cannot be applied uniformly across all industrial sectors?
(a)

Differences in market structure

(b)

Differences in product demand

(c)

Differences in dominant emission sources

(d)

Differences in labour intensity

Explanation

Different industrial sectors emit greenhouse gases from fundamentally different stages of production.

Some sectors are dominated by process emissions.

Others are dominated by electricity-related emissions.

Therefore, the sequence and choice of decarbonisation measures must differ.

Core Logic: The determining constraint is the dominant emission source, not market structure, labour use, or demand patterns.

Why other options are wrong:

(a) Market structure does not determine emission chemistry.

(b) Demand size does not change emission pathways.

(d) Labour intensity has no bearing on emission origin.

Answer: (c)
Q3. India’s nuclear establishment is prioritising the development of indigenous Light Water Reactors (LWRs) even though it already has deep expertise in heavy water reactors. From a systems perspective, this is primarily because:
(a)

LWRs are the only reactor type that can use imported nuclear fuel

(b)

Export integration requires compatibility with the globally dominant reactor architecture

(c)

Heavy water reactors cannot be scaled beyond a certain megawatt capacity

(d)

LWRs are inherently safer than all other reactor types

Explanation

Structural Context: India’s heavy water reactor programme is technologically mature, but global nuclear trade, vendor ecosystems, component standards, and fuel logistics are overwhelmingly centred on Light Water Reactor (LWR) platforms.

System Constraint: Without domestic capability in the globally dominant architecture, Indian firms cannot integrate into international nuclear supply chains or participate in reactor exports.

Core Logic: Hence, the driving constraint is market architecture compatibility, not any technical limitation of PHWRs.

Why other options are wrong:

(a) PHWRs also use imported fuel where required.

(c) India already operates 700 MWe PHWRs.

(d) Safety is not the structural reason cited for the LWR shift.

Answer: (b)
Q4. In India’s nuclear sector reform, the SHANTI Act most closely performs which of the following systemic functions?
(a)

Technology substitution

(b)

Market ecosystem integration

(c)

Energy resource diversification

(d)

Cost minimisation

Explanation

Structural Role: The SHANTI Act does not change reactor physics or fuel chemistry.

Systemic Function: Its primary role is to open the sector to private and foreign-linked activity, enabling component manufacturing, reactor exports, and global vendor participation.

Core Logic: Thus, it functions as an institutional bridge between India’s nuclear sector and the dominant global LWR ecosystem — just as wetlands function as filters, not water sources.

Why others are wrong:

(a) It does not replace reactor technology.

(c) It does not diversify energy sources.

(d) Cost effects are secondary, not its systemic role.

Answer: (b)
Q5. Which one of the following best explains why thorium cannot directly replace uranium as a primary nuclear fuel in the first stage of India’s programme?
(a)

Thorium is less radioactive than uranium

(b)

Thorium is not fissile in its natural form

(c)

Thorium reactors require heavy water

(d)

Thorium cannot produce fast neutrons

Q6. In the architecture of India’s three-stage nuclear programme, Fast Breeder Reactors (FBRs) most closely perform which of the following systemic functions?
(a)

Energy maximisation

(b)

Fuel multiplication

(c)

Waste reduction

(d)

Power diversification

Explanation

Core Function: FBRs are designed to produce more fissile material than they consume.

Fuel Conversion: They convert U-238 → Pu-239 and enable the thorium cycle by supplying starter material.

System Logic: Thus, their systemic role is fuel multiplication, not merely power generation.

Why others are wrong:

(a) Energy is a by-product, not the system purpose.

(c) Waste reduction is not the design objective.

(d) They do not diversify power sources.

Answer: (b)