Prelims Solution

Q. Consider the following statements : I. It is expected that Majorana 1 chip will enable quantum computing.

Q. Consider the following statements :
I. It is expected that Majorana 1 chip will enable quantum computing.
II. Majorana 1 chip has been introduced by Amazon Web Services (AWS).
III. Deep learning is a subset of machine learning.

Which of the statements given above are correct?

(a) I and II only
(b) II and III only
(c) I and III only
(d) I, II and III

UPSC Prelims 2025 GS Paper's Solution

Explanation : 

Majorana 1 quantum chip

The Majorana 1 quantum chip, introduced by Microsoft (not Amazon Web Services), represents a significant advancement in quantum computing through its use of topological qubits, which enhance stability and scalability.

Deep learning is a specialized area within machine learning that utilizes neural networks composed of multiple interconnected layers to model complex patterns and relationships in large datasets effectively.

Q. Consider the following statements : I. It is expected that Majorana 1 chip will enable quantum computing. Read More »

Q. What is the common characteristic of the chemical substances generally known as CL-20, HMX and LLM-105, which are sometimes talked about in media?

Q. What is the common characteristic of the chemical substances generally known as CL-20, HMX and LLM-105, which are sometimes talked about in media?

(a) These are alternatives to hydrofluorocarbon refrigerants
(b) These are explosives in military weapons
(c) These are high-energy fuels for cruise missiles
(d) These are fuels for rocket propulsion

Correct Answer: (b) These are explosives in military weapons.

UPSC Prelims 2025 GS Paper's Solution

Explanation : 

CL-20, HMX and LLM-105

CL-20 (hexanitrohexaazaisowurtzitane), HMX (octogen) and LLM-105 are all high-performance military explosives. They are prized for their very high detonation velocities and pressures and are used in advanced warheads, shaped charges and propellant formulations. They are not refrigerants or conventional fuels.

Q. What is the common characteristic of the chemical substances generally known as CL-20, HMX and LLM-105, which are sometimes talked about in media? Read More »

Q. Coal gasification technology can be used in the production of how many of them?

Q. Consider the following substances :
I. Ethanol
II. Nitroglycerine
III. Urea

Coal gasification technology can be used in the production of how many of them?

(a) Only one
(b) Only two
(c) All the three
(d) None

Correct Answer: (c) All the three

UPSC Prelims 2025 GS Paper's Solution

Explanation : 

Coal gasification

Coal gasification produces a synthesis gas (syngas) mixture of CO and H₂, which serves as a versatile building-block for many downstream chemicals:

Ethanol
– Syngas → (Fischer–Tropsch or direct catalytic) → ethanol
– Or via syngas fermentation by specialized microbes

Nitroglycerine
– Syngas → NH₃ (Haber–Bosch) → HNO₃ (Ostwald process)
– HNO₃ + glycerol → nitroglycerine (nitration)

Urea
– Syngas → NH₃
– Syngas also supplies CO₂
– NH₃ + CO₂ → ammonium carbamate → urea

Since all three—ethanol, nitroglycerine (via HNO₃ from NH₃), and urea—can be derived ultimately from coal-derived syngas, the correct answer is (c) all three.

Q. Coal gasification technology can be used in the production of how many of them? Read More »

Q. Consider the following : I. Cigarette butts II. Eyeglass lenses III. Car tyres How many of them contain plastic?

Q. Consider the following :
I. Cigarette butts
II. Eyeglass lenses
III. Car tyres

How many of them contain plastic?

(a) Only one
(b) Only two
(c) All the three
(d) None

Correct Answer: (c) All the three

UPSC Prelims 2025 GS Paper's Solution

Explanation :

I. Cigarette butts: Cigarette butts contain cellulose acetate, a type of plastic.

II. Eyeglass lenses: Most modern eyeglass lenses are made from plastic materials such as polycarbonate or CR-39 (plastic polymer).

III. Car tyres: Car tyres contain synthetic rubber, which is a polymer-based plastic material.

Thus, all three items listed contain plastic.

Q. Consider the following : I. Cigarette butts II. Eyeglass lenses III. Car tyres How many of them contain plastic? Read More »

Q. In the context of electric vehicle batteries, consider the following elements:

Q. In the context of electric vehicle batteries, consider the following elements:

I. Cobalt
II. Graphite
III. Lithium
IV. Nickel

How many of the above usually make up battery cathodes?

(a) Only one
(b) Only two
(c) Only three
(d) All the four

Correct Answer: (c) Only three

UPSC Prelims 2025 GS Paper's Solution

Explanation : 

In lithium-ion batteries used in electric vehicles, the battery cell primarily consists of two electrodes: the cathode (positive electrode) and the anode (negative electrode).

Cathode (Positive Electrode):

The cathode typically contains lithium-based metal oxides. Common cathode materials include:

Lithium (Li): Essential component in cathode materials, present as lithium ions.
Cobalt (Co): Used in cathodes such as Lithium Cobalt Oxide (LiCoO₂).
Nickel (Ni): Used in cathodes such as Nickel-Manganese-Cobalt (NMC) or Nickel-Cobalt-Aluminum (NCA) chemistries.

Thus, Lithium, Cobalt, and Nickel are commonly found in cathode materials.

Anode (Negative Electrode):

The anode typically consists of carbon-based materials, most commonly:

Graphite: Widely used as the anode material due to its ability to intercalate lithium ions efficiently.

Hence, the correct answer is option (c) Only three.

 

 

Q. In the context of electric vehicle batteries, consider the following elements: Read More »

Q. With reference to Unmanned Aerial Vehicles (UAVs), consider the following statements :

Q. With reference to Unmanned Aerial Vehicles (UAVs), consider the following statements :

I. All types of UAVs can do vertical landing.
II. All types of UAVs can do automated hovering.
III. All types of UAVs can use battery only as a source of power supply.

How many of the statements given above are correct?

(a) Only one
(b) Only two
(c) All the three
(d) None

Correct Answer: (d) None

UPSC Prelims 2025 GS Paper's Solution

Explanation : 

I. “All types of UAVs can do vertical landing.” This statement is incorrect. UAVs come in various types, such as fixed-wing UAVs, rotary-wing UAVs (multirotors), and hybrid UAVs. Fixed-wing UAVs typically require a runway or landing strip and cannot perform vertical landings. Only rotary-wing or hybrid UAVs can perform vertical landings.

II. “All types of UAVs can do automated hovering.” This statement is incorrect. Fixed-wing UAVs cannot hover in place because they rely on forward motion to generate lift. Only rotary-wing UAVs (such as quadcopters or helicopters) or certain hybrid UAVs can hover.

III. “All types of UAVs can use battery only as a source of power supply.” This statement is incorrect. While many small UAVs use batteries, larger UAVs or specialized UAVs may use other power sources such as gasoline engines, hybrid power systems, solar power, or fuel cells.

Thus, none of the given statements are correct.

Q. With reference to Unmanned Aerial Vehicles (UAVs), consider the following statements : Read More »

Q. How many of the above are considered as alternative powertrain vehicles?

Q. Consider the following types of vehicles :
I. Full battery electric vehicles
II. Hydrogen fuel cell vehicles
III. Fuel Cell electric hybrid vehicles

How many of the above are considered as alternative powertrain vehicles?

(a) Only one
(b) Only two
(c) All the three
(d) None

Correct Answer: (c) All the three

UPSC Prelims 2025 GS Paper's Solution

Explanation : 

Alternative powertrain vehicles

Alternative powertrain vehicles refer to vehicles that use propulsion systems other than conventional internal combustion engines powered solely by gasoline or diesel. The given types of vehicles are:

I. Full battery electric vehicles (BEVs): These vehicles run entirely on electricity stored in batteries and do not use conventional fuels.

II. Hydrogen fuel cell vehicles (FCVs): These vehicles use hydrogen gas to generate electricity through fuel cells, powering an electric motor. They emit only water vapor as exhaust.

III. Fuel cell electric hybrid vehicles: These vehicles combine hydrogen fuel cell technology with battery-electric technology, using both fuel cells and batteries to power the vehicle.

All three types mentioned above represent alternative powertrain technologies, as they deviate from traditional internal combustion engine vehicles. Hence, the correct answer is option (c) All the three.

Q. How many of the above are considered as alternative powertrain vehicles? Read More »

Paragraph: Unlike religion and science, poetry does not posit or expect any belief in absolute truths.

Paragraph: Unlike religion and science, poetry does not posit or expect any belief in absolute truths.

Those forces or individuals who claim to have absolute truths in their grasp tend to turn dictatorial and tyrannical. Truth usually does not admit any contradictions or imperfections. It is unitarian. It is, therefore, not of much use for poetry. Poetry abides by the plurality of life and existence. Perhaps poetry follows reality which is plural, anachronistic, full of contradictions. Against the tyranny of truth, poetry remains a partisan of democratic reality. Against the arrogance of power, wealth and hierarchy, poetry proposes both humility and defiance.

Q. Which one of the following statements best reflects the most logical and rational message conveyed by the above passage?
a) It is the poetry, not science or religion, which recognizes and accepts imperfections in humans.
b) Truth is revealed through science or religion and poetry is anathema to truth.
c) Poetry is romantic, imaginary and is about feeling whereas science and religion are about truth.
d) In a world of violence, tyranny and bigotry, poetry is a form of dynamic resistance.
Correct answer: d) In a world of violence, tyranny and bigotry, poetry is a form of dynamic resistance.

Question from UPSC Prelims 2024 CSAT

Explanation : 

The passage emphasizes that poetry does not claim absolute truths, unlike religion and science. It argues that absolute truths can lead to tyranny and dictatorship, as truth is unitarian and intolerant of contradictions. Poetry, on the other hand, embraces plurality, contradictions, and imperfections. It is described as a partisan of democratic reality, standing against the tyranny of truth and the arrogance of power, wealth, and hierarchy. Thus, poetry is presented as a form of resistance against oppressive forces, making option (d) the most logical and rational message conveyed by the passage.

Option (a) is incorrect because the passage does not explicitly state that poetry alone recognizes human imperfections. Option (b) is incorrect because the passage does not suggest poetry is anathema (completely opposed) to truth; rather, it suggests poetry does not posit absolute truths. Option (c) is incorrect because the passage does not characterize poetry as merely romantic or imaginary; rather, it emphasizes poetry’s role in embracing plurality and resisting tyranny.

Paragraph: Unlike religion and science, poetry does not posit or expect any belief in absolute truths. Read More »

Paragraph: Evolution has endowed caterpillars that feed on corn with a unique ability,

Paragraph: Evolution has endowed caterpillars that feed on corn with a unique ability,

they can induce the plant to turn off its defence against insect predators. This helps caterpillars to eat more and grow faster. The agent that causes this effect is the caterpillar’s faeces or frass. The find could throw new light on compounds associated with plant response to pathogens like fungi or bacteria.

Q. Which one of the following statements best reflects the most logical, rational, and practical message conveyed by the passage?
a) Farmers can use caterpillars to feed on weeds in their crop fields/ plantations.
b) This finding can help in the development of clinically useful antimicrobial compounds.
c) This finding can help in the development of organic, ecologically sustainable pesticides.
d) Caterpillars can be genetically modified to be predators of the other plant pests.
Correct answer: c) This finding can help in the development of organic, ecologically sustainable pesticides.

Question from UPSC Prelims 2024 CSAT

Explanation : 

1. Key focus: Caterpillars use frass to disable corn plant defenses, related to plant-pathogen responses

2. Evaluating options:
a) Weed control – Not related to passage
b) Antimicrobials – Only tangentially related
c) Organic pesticides – Most logical application as it directly connects to understanding plant defense mechanisms
d) GM caterpillars – Not supported by passage

Option (c) is correct because understanding how pests naturally disable plant defenses could lead to developing organic pesticides that work with plant defense mechanisms.

Paragraph: Evolution has endowed caterpillars that feed on corn with a unique ability, Read More »

Paragraph: Geographers analyzed 175 satellite images of ocean colour,

Paragraph: Geographers analyzed 175 satellite images of ocean colour,

which is an indicator of Phytoplankton productivity at the ocean’s surface, and found that giant icebergs are responsible for storing up to 20 percent of carbon in the Southern Ocean. The researchers discovered that melting water from giant icebergs which contains iron and other nutrients, supports hitherto unexpectedly high levels of phytoplankton growth.

Q. Based on the above passage, the following assumptions have been made:
1. Giant icebergs have a bearing on primary productivity and food chains of the Southern Ocean.
2. Melting of giant icebergs can produce climate change effects and impact world fisheries.

Which of the assumptions given above is/are valid?
a) 1 only
b) 2 only
c) Both 1 and 2
d) Neither 1 nor 2
Correct answer: a) 1 only

Question from UPSC Prelims 2024 CSAT

Explanation : 

Assumption 1 is valid:
The passage clearly states that melting water from giant icebergs contains iron and other nutrients, which support unexpectedly high levels of phytoplankton growth. Phytoplankton form the base of marine food chains, and their productivity directly influences primary productivity and the entire food web in the Southern Ocean. Thus, giant icebergs indeed have a bearing on primary productivity and food chains.

Assumption 2 is valid:
The passage mentions that giant icebergs are responsible for storing up to 20 percent of carbon in the Southern Ocean. Phytoplankton growth, stimulated by nutrients from melting icebergs, plays a significant role in carbon sequestration. Changes in carbon storage and phytoplankton productivity can influence global climate patterns. Additionally, phytoplankton productivity directly impacts marine ecosystems and fisheries worldwide, as phytoplankton form the foundation of marine food webs.

Thus, both assumptions are logically valid based on the information provided in the passage.

Paragraph: Geographers analyzed 175 satellite images of ocean colour, Read More »