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Home » UPSC Prelims Quiz » UPSC Prelims Quiz: April 20, 2026

UPSC Prelims Quiz: April 20, 2026

Q1. With reference to ethanol blending in India, consider the following statements:

1. The target of 20 percent ethanol blending in petrol was advanced to Ethanol Supply Year 2025–26.

2. The permissible feedstock base includes sugarcane juice, sugar beet, cassava, damaged food grains, rotten potatoes, and surplus grains.

3. The Ethanol Blended Petrol Programme was launched in January 2003.

Which of the statements given above are correct?

(a)

1 and 2 only

(b)

2 and 3 only

(c)

1 and 3 only

(d)

1, 2 and 3

Explanation

Statement 1 – Correct: The National Policy on Biofuels, 2018 as amended in 2022 advanced the target of 20 percent ethanol blending in petrol to Ethanol Supply Year 2025–26 from the earlier target year of 2030.

Statement 2 – Correct: The widened feedstock base includes sugarcane juice, sugar beet, cassava, damaged food grains, rotten potatoes, and surplus grains. This is part of the expanded policy support for ethanol production.

Statement 3 – Correct: The Ethanol Blended Petrol Programme was launched in January 2003, after pilot projects had begun in 2001 at Miraj, Manmad, and Aonla-Bareilly.

Answer: (d)
Q2. With reference to fuel characteristics of ethanol-blended petrol, consider the following statements:

1. Ethanol improves anti-knocking properties because of its higher octane value.

2. E20 may lead to a marginal reduction in mileage because ethanol has lower energy density than petrol.

3. Ethanol can be easily transported through conventional petroleum pipelines without additional logistical adjustments.

Which of the statements given above is/are correct?

(a)

1 and 2 only

(b)

2 only

(c)

1 and 3 only

(d)

1, 2 and 3

Explanation

Statement 1 – Correct: Ethanol has a higher octane value than petrol and therefore raises the anti-knocking quality of the blended fuel. Pure ethanol has a Research Octane Number in the range of about 108–110, whereas regular petrol is much lower. This greater knock resistance helps prevent premature ignition inside the cylinder and supports smoother combustion under compression.

Statement 2 – Correct: Ethanol has lower energy density than petrol, which means the energy available per unit volume of fuel declines when the ethanol share rises. Because of this, E20 can produce a marginal reduction in fuel economy or mileage, especially in vehicles not specifically optimised for higher-ethanol blends. The decline is linked to the lower calorific content of ethanol, even though combustion quality may improve.

Statement 3 – Incorrect: Ethanol cannot be easily transported through conventional petroleum pipelines because its physical properties create significant handling constraints. Ethanol is hygroscopic, meaning it readily attracts and absorbs water. If moved through pipelines containing residual water, it may absorb moisture and undergo phase separation from petrol, which affects fuel quality and can damage engines. This is why ethanol movement requires dedicated storage, specialised transport arrangements, and added logistics support instead of simple use of the conventional petroleum pipeline system.

Answer: (a)
Q3. Which one of the following best explains why second-generation ethanol is viewed as a more sustainable pathway within the ethanol strategy?
(a)

It is produced mainly from sugarcane juice and B-heavy molasses

(b)

It is produced from ligno-cellulosic biomass and agricultural residues

(c)

It eliminates the need for specialised storage and transport infrastructure

(d)

It ensures that ethanol-blended petrol remains cheaper than non-blended petrol

Explanation

Option (a) – Incorrect: Sugarcane juice and B-heavy molasses belong to the existing first-generation feedstock structure. This option uses familiar ethanol terms but assigns them to the wrong generation.

Option (b) – Correct: Second-generation ethanol is produced from ligno-cellulosic biomass and residues such as rice straw, wheat straw, corn cobs, stubble, bagasse, bamboo, and woody biomass. Its policy relevance lies in reducing pressure on food crops while using agricultural waste productively.

Option (c) – Incorrect: The source notes continued logistical constraints, including the need for dedicated storage and specialised transport. Second-generation ethanol does not remove these downstream infrastructure requirements.

Option (d) – Incorrect: Pricing changes have altered the earlier expectation that ethanol-blended petrol would necessarily remain cheaper than non-blended petrol. Therefore, price advantage is not the defining reason for second-generation ethanol’s importance.

Answer: (b)
Read Full Article
Ethanol Blending In India And The Debate On Energy Transition
Read the full detailed article on ethanol blending, E20 rollout, energy security, food-fuel debate, vehicle compatibility, and environmental concerns.
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Q4. With reference to India’s space sustainability efforts, consider the following:

1. NETRA

2. MOTR

3. Baker Nunn Schmidt Telescope

Which of the above are part of India’s indigenous efforts for tracking or monitoring space objects?

(a)

1 and 2 only

(b)

2 and 3 only

(c)

1 and 3 only

(d)

1, 2 and 3

Explanation

Statement 1 – Correct: NETRA, or Network for Space Objects Tracking and Analysis, is listed as an indigenous effort related to tracking space objects.

Statement 2 – Correct: MOTR at Sriharikota is part of the indigenous space sustainability effort.

Statement 3 – Correct: The Baker Nunn Schmidt Telescope, though under refurbishment at Nainital, is also included among the indigenous efforts.

Answer: (d)
Q5. Consider the following pairs:

1. DFSM — ISRO initiative declared in 2024 for debris free space missions by 2030

2. MOTR — Nainital

3. BNST — Sriharikota

4. IADC — global forum on space debris coordination

How many pairs given above are correctly matched?

(a)

Only one

(b)

Only two

(c)

Only three

(d)

All four

Explanation

Pair 1 – Correct: DFSM was declared in 2024 as part of ISRO’s effort toward debris free space missions by 2030. It should not be described as a mandate binding all global space actors.

Pair 2 – Incorrect: MOTR is located at Sriharikota, not at Nainital.

Pair 3 – Incorrect: BNST refers to the Baker Nunn Schmidt Telescope, which is being refurbished at Nainital, not at Sriharikota.

Pair 4 – Correct: The Inter-Agency Space Debris Coordination Committee is one of the global fora associated with space debris coordination in which India participates.

Answer: (b)
Q6. With reference to Marine Heat Waves, consider the following statements:

1. A marine heat wave is identified when the sea-surface temperature of a particular region remains about 3°C to 4°C above average for at least five days.

2. Marine heat waves are only short-duration events and cannot persist beyond a few weeks.

3. Marine heat waves can intensify harmful algal blooms and disturb marine species distribution.

Which of the statements given above are correct?

(a)

1 and 3 only

(b)

2 only

(c)

1 and 2 only

(d)

1, 2 and 3

Explanation

Statement 1 – Correct: Marine heat waves are described as periods in which the surface temperature of a particular sea region rises about 3°C to 4°C above average for at least five days.

Statement 2 – Incorrect: These events are not confined to a few weeks. They may last for weeks, months, or even years.

Statement 3 – Correct: Marine heat waves can shift the population of marine species, disrupt fish ecosystems, and exacerbate harmful algal blooms.

Answer: (a)
Additional Prelims Facts

Vulnerability of non-mobile species: Non-mobile marine species such as corals, algae and sponges are especially vulnerable during marine heat waves because they are less able to escape thermal stress.

Rising frequency: Marine heat waves have increased in frequency, with their number having doubled since 1982.

Wider impact: The phenomenon can also increase the likelihood of extreme weather events.

Q7. Consider the following pairs:

1. Cyclones — Indian Ocean

2. Hurricanes — Atlantic

3. Typhoons — Western Pacific and South China Sea

4. Willy-willies — Western Australia

How many of the above pairs are correctly matched?

(a)

Only one

(b)

Only two

(c)

Only three

(d)

All four

Explanation

Pair 1 – Correct: The term “cyclones” is used for these storms in the Indian Ocean.

Pair 2 – Correct: The term “hurricanes” is used in the Atlantic.

Pair 3 – Correct: The term “typhoons” is used in the Western Pacific and the South China Sea.

Pair 4 – Correct: “Willy-willies” is the regional name used for tropical cyclones in Western Australia.

Answer: (d)
Additional Prelims Facts

Favourable conditions: Tropical cyclones originate over tropical oceans and intensify under conditions such as sea-surface temperatures above 27°C, sufficient Coriolis force, low vertical wind shear, a pre-existing low-pressure system, and upper-level divergence.

Formation dynamics: A weak low-pressure area or low-level cyclonic circulation acts as the initial trigger for cyclone development over warm ocean waters.

Major impacts: On landfall, tropical cyclones bring violent winds, heavy rainfall, and storm surges, leading to widespread coastal and inland damage.