UPSC Essentials | Daily subject-wise quiz : Science and Technology MCQs on polycrystalline cathodes, Small Satellite Launch Vehicle and more (Week 143)

3. It can be used to take a satellite to Geosynchronous orbit.

How many of the statements given above are correct?

(a) Only one

(b) Only two

(c) All three

(d) None

Relevance: This question tests factual clarity on ISRO’s launch vehicles, a high-frequency area in Science & Technology for UPSC Prelims. SSLV is often in news due to private sector participation, small satellite launches, and space reforms, making such statement-based questions highly probable.

Explanation

— ISRO carried out a successful static test of an improved version of the third stage (SS3) of Small Satellite Launch Vehicle (SSLV) on December 30, 2025 at the Solid Motor Static Test Facility of Satish Dhawan Space Centre, Sriharikota.

— ISRO’s Small Satellite Launch Vehicle (SSLV) is a three-stage Launch Vehicle configured with three Solid Propulsion Stages. It also has a liquid propulsion-based Velocity Trimming Module (VTM) as a terminal stage, which can help adjust the velocity as it prepares to place the satellite. Hence, statement 1 is not correct.

— The aim behind SSLVs is to produce low-cost launch vehicles with short turnaround times and minimal infrastructural requirements. The SSLV can launch satellites weighing up to 500 kg and accommodate multiple satellites. Hence, statement 2 is correct.

— SSLV is meant for placing small satellites into Low Earth Orbit (LEO) and Sun-Synchronous Polar Orbit, not Geosynchronous Orbit (GSO). Hence, statement 3 is not correct.

Therefore, option (a) is the correct answer.

QUESTION 2

With reference to the polycrystalline cathodes, consider the following statements:

1. Traditional lithium-ion batteries commonly use polycrystalline nickel-rich cathode materials.

2. In polycrystalline cathodes, the degradation happens inside the crystal itself.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Relevance: The question tests conceptual clarity on lithium-ion battery technology, a recurring theme in science & technology current affairs. It also links energy storage, electric mobility, and clean energy transitions, which are high-frequency UPSC Prelims areas.

Explanation

— Traditional lithium-ion batteries commonly use polycrystalline nickel-rich cathode materials. These are made of many tiny crystal grains packed together. Each time a battery charges and discharges, these grains slightly expand and contract. Over thousands of cycles of charging and discharging, the motion strains the boundaries between grains, causing them to fracture and form minor cracks. Once those are formed, liquid electrolyte can seep inside, causing unwanted chemical reactions, resulting in oxygen release, and a gradual loss of capacity and exhaustion of the battery. Hence, statement 1 is correct.

— To avoid this, researchers shifted toward single-crystal cathodes. Unlike their polycrystalline counterparts, single-crystal materials lack internal grain boundaries. In theory, that meant fewer weak points and a much longer lifespan. In practice, however, the results were inconsistent. Some single-crystal batteries degraded faster than expected, puzzling engineers who believed they had already solved the mechanical problem.

— In polycrystalline cathodes, damage accumulates between grains. In single-crystal cathodes, the degradation happens inside the crystal itself. Cutting-edge imaging techniques revealed that chemical reactions during charging do not proceed evenly across a single particle. Some regions react faster than others, leading to uneven expansion and contraction within the same crystal. Hence, statement 2 is not correct.

Therefore, option (a) is the correct answer.

QUESTION 3

The ‘mycoheterotroph’ refers to:

(a) A plant that derives nutrition by preying on insects

(b) A plant that obtains nutrients from fungi instead of photosynthesis

(c) A fungus that parasitises plant roots

(d) A microorganism that fixes atmospheric nitrogen

Relevance: The question checks conceptual clarity on alternative modes of nutrition in organisms, a core science concept frequently tested in UPSC Prelims. Such terms are often linked with scientific discoveries of rare species and ecosystem functioning, connecting static science with current affairs.

Explanation

— A bizarre plant was discovered near Kuala Lumpur, Malaysia, on the periphery of a forest preserve’s picnic area. This plant, called a fairy lantern, is a parasite that steals all its energy and nutrients from mycorrhizal fungi that dwell within the soil. Usually hidden underground, the fairy lantern periodically produces a pinkish flower with a domed top, shaped like an umbrella, from which three tentacle-like structures extend.

(Gim Siew Tan, NYT)

— The fairy lantern is a mycoheterotroph, the general term for a plant that parasitizes fungi. There are only around 550 known species of mycoheterotrophs worldwide, such as waxy white ghost pipes, said Vincent Merckx, a biologist at the Naturalis Biodiversity Center in the Netherlands, who was not involved with the paper. That is a small fraction of the estimated 435,000 plant species on Earth.

— The ‘mycoheterotroph’ refers to a plant that obtains nutrients from fungi instead of photosynthesis. It is an organism (usually a plant) that lacks chlorophyll and obtains its carbon and nutrients from fungi, rather than through photosynthesis.

Therefore, option (b) is the correct answer.

QUESTION 4

Artificial way of causing rainfall to reduce air pollution makes use of: (UPSC 2025)

(a) silver iodide and potassium iodide

(b) silver nitrate and potassium iodide

(c) silver iodide and potassium nitrate

(d) silver nitrate and potassium chloride

Relevance: The question tests awareness of cloud seeding technology, a key Science & Technology topic linked to air pollution control and weather modification in current affairs.

Explanation

— The India Meteorological Department (IMD) classifies October to December as the period of the post-monsoon season. This means that the rain-bearing, moisture-laden monsoon clouds and the associated synoptic systems, like monsoonal low pressures or depressions (which trigger rainfall), would be largely absent.

— The winds are calm, and atmospheric conditions largely favour dry weather conditions during this season, unless triggered by the passing western disturbances at lower latitudes. Western disturbances cause rain and snow over north and northwest India during the post-monsoon/winter seasons.

— Cloud seeding is a weather modification technique that involves dispersing substances such as silver iodide/potassium iodide or sodium chloride into clouds to encourage rainfall.

Therefore, option (a) is the correct answer.

QUESTION 5

Consider the following pairs:

1. Randomly-generated numbers – Foundation on which modern encryption systems and security architectures are built.

2. Pseudorandom numbers – Generated through computer algorithms.

Which of the pairs given above is/are correctly matched?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Relevance: This question checks understanding of core concepts in cryptography and cybersecurity, especially the distinction between true random and pseudorandom numbers, which is a recurring UPSC Prelims theme in Science & Technology.

Explanation

— Randomly-generated numbers are critical to digital security. In fact, very large randomly-generated numbers are the foundation on which modern encryption systems and security architectures are built. The defining feature of such numbers is that they are created in completely random processes, not by following any pattern or algorithm. As a result, they cannot be guessed or predicted. Anything built on top of them — passwords, encryption keys, or authentication systems – become highly secure against hacking. Hence, pair 1 is correct.

— Our current systems, however, do not use truly random numbers. Instead, they use what are known as pseudorandom numbers, generated through computer algorithms. These algorithms are sophisticated enough to ensure that the very large numbers they produce appear random and are extremely difficult to predict without knowledge of how the algorithm works, as well as its initial input. Hence, pair 2 is correct.

— These pseudorandom numbers are good enough for securing our existing networks and information systems. Even the fastest computers, applying brute-force algorithms, would take centuries or longer to decode the passwords or encryption keys based on these numbers.

Therefore, option (c) is the correct answer.

Previous Daily Subject-Wise-Quiz

Daily Subject-wise quiz — History, Culture, and Social Issues (Week 138)

Daily subject-wise quiz — Polity and Governance (Week 143)

Daily subject-wise quiz —  Science and Technology (Week 142)

Daily subject-wise quiz — Economy (Week 142)

Daily subject-wise quiz — Environment and Geography (Week 142)

Daily subject-wise quiz – International Relations (Week 142)

Subscribe to our UPSC newsletter and stay updated with the news cues from the past week.

Stay updated with the latest UPSC articles by joining our Telegram channel – IndianExpress UPSC Hub, and follow us on Instagram and X.