UPSC Prelims 2026: Science and Technology MCQs - Practice Quiz

Science & Technology Practice Quiz

1. Pollutants and Their Sources

With reference to the pollutants and their sources, consider the following pairs:

1. PM 2.5: Predominantly produced by vehicle emissions and thermal power plants.
2. Nitrogen dioxide: Produced primarily due to the burning of fossil fuels by vehicles, thermal power plants, and industrial processes.
3. Soot: It comes from sources such as vehicle exhaust emissions and burning wood.

How many of the pairs given above are correctly matched?

• (a) Only one pair
• (b) Only two pairs
• (c) All three pairs
• (d) None of the above

Explanation: All matches are accurate. PM 2.5 and NO₂ are major byproducts of high-temperature combustion in engines and power plants. Soot (Black Carbon) results from the incomplete combustion of organic matter like diesel and wood.

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2. Earthquake Terminology

The term “hypocenter” with reference to an earthquake refers to:

• (a) The location below the Earth’s surface where the earthquake starts
• (b) The location on the surface of the Earth where it cracks
• (c) The location from where the seismograph measures intensity
• (d) The location adjacent to the seismically prone region

Explanation: The hypocenter (or focus) is the point within the earth where the rupture starts. The epicenter is the point directly above it on the surface.

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3. Ham Radio (Amateur Radio)

Consider the following statements regarding 'ham' radio:

1. It is used for educational and knowledge purposes.
2. Communication can be set up between two licensed hams.
3. In India, individuals below the age of 21 are not permitted to operate a ham radio.

Which of the statements given above is/are correct?

• (a) 1 and 2 only
• (b) 2 only
• (c) 2 and 3 only
• (d) 1, 2 and 3

Explanation: Statement 3 is incorrect. In India, any citizen above the age of 12 can obtain a license to operate a ham radio after passing the necessary examination.

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4. Indian Space Research Organisation (ISRO)

Consider the following statements:

1. It was established as a successor to INCOSPAR in 1969.
2. It is the nodal space agency under the Department of Space (DoS), formed in 1972.
3. Its core mandate includes designing launch vehicles and applying space technology for societal development.
4. ISRO functions autonomously under the Ministry of Science & Technology.

Which of the statements given above are correct?

• (a) 1 and 4 only
• (b) 1, 2 and 3 only
• (c) 2 and 4 only
• (d) All of the above

Explanation: Statement 4 is incorrect because ISRO falls under the Department of Space, which reports directly to the Prime Minister’s Office (PMO), not the Ministry of Science & Technology.

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5. Population III Stars

What are Population III stars?

• (a) The first stars in the universe
• (b) The recent stars in the universe
• (c) The smallest, long-living, dim stars
• (d) None of the above

Explanation: Population III stars are the hypothetical first generation of very massive, hot stars that contained almost no "metals" (elements heavier than helium), formed shortly after the Big Bang.

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6. Reionization

Consider the following statements regarding ‘reionization’:

1. It allows us to indirectly study the earliest stars.
2. Scientists have recently discovered data on when the reionization process occurred.

Which of the above given statements is/are correct?

• (a) 1 only
• (b) 2 only
• (c) Both 1 and 2
• (d) Neither 1 nor 2

Explanation: Reionization is the process where the first stars/galaxies ionized neutral hydrogen. Observations from the James Webb Space Telescope have been instrumental in dating this era.

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7. Gaia Mission

Consider the following statements regarding the Gaia mission:

1. It maps the cosmos through precise measurement of stars.
2. Gaia was positioned in the Lagrange point 1 (L1).
3. The data allowed for a 3D map of the galaxy.
4. The mission was launched by NASA.

How many of the statements given above are correct?

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

Explanation: Statements 1 and 3 are correct. Statement 2 is incorrect (it is at L2). Statement 4 is incorrect (it is a European Space Agency mission).

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8. Perseid Meteors

Consider the following statements:

1. It can be seen from anywhere in the Southern Hemisphere.
2. Perseids are known for their fireballs.
3. The name derives from the Perseus constellation.

How many of the statements given above are correct?

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

Explanation: Statement 1 is incorrect as they are primarily a Northern Hemisphere phenomenon. Statements 2 and 3 are correct.

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9. Blue Sky Phenomenon

The blue of the sky is a result of:

• (a) Scattering of light
• (b) Interference of light
• (c) Polarization of light
• (d) Total Internal Reflection

Explanation: Known as Rayleigh scattering, shorter blue wavelengths are scattered in all directions by gas molecules in the atmosphere.

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10. Graphene Properties

Which of the following statements about Graphene is NOT correct?

1. It is an electrically and thermally conductive material.
2. It is a two-atom-thick layer of carbon atoms arranged in a square lattice.

Select the correct answer:

• (a) 1 only
• (b) 2 only
• (c) Both 1 and 2
• (d) Neither 1 nor 2

Explanation: Statement 2 is incorrect because Graphene is one-atom-thick and arranged in a hexagonal (honeycomb) lattice.