UPSC CDS-2 Archives

1. Mission Shakti (DRDO) of India is related to which one among the follo

Mission Shakti (DRDO) of India is related to which one among the following ?

Launch of multiple satellites using a single rocket

Launch of heavy satellites

Use of high power rockets in launching of satellites

Use of rocket to destroy an orbiting satellite

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UPSC CDS-2 – 2024

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Mission Shakti (DRDO) is related to the use of a rocket to destroy an orbiting satellite.

– Mission Shakti was the codename for India’s first anti-satellite (ASAT) missile test, conducted by the Defence Research and Development Organisation (DRDO) on 27 March 2019.
– The test involved the successful destruction of an Indian satellite in low Earth orbit (LEO) using a ground-based missile.
– This test demonstrated India’s capability to intercept and destroy orbiting targets, establishing it as the fourth country (after the US, Russia, and China) with this capability.

The test aimed to demonstrate India’s technological capability in space defence and security. The target satellite was MicrosaT-R, an Indian satellite. The debris generated by the test was stated to be minimized by conducting the test at a relatively low altitude, intended to ensure that the debris would decay quickly.

2. A sound wave having frequency of 300 Hz is travelling in an unknown me

A sound wave having frequency of 300 Hz is travelling in an unknown medium. Its wavelength is not known. It travels a distance equal to 150 times its wavelength in time t. The value of t is :

0.5 s

1 s

1.5 s

2 s

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UPSC CDS-2 – 2024

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The time taken for the sound wave to travel the given distance is 0.5 s.

– The speed of a wave (v) is given by the product of its frequency (f) and wavelength (λ): v = f * λ.
– The distance travelled (d) is given as 150 times the wavelength: d = 150λ.
– The relationship between speed, distance, and time (t) is v = d / t.
– Combining these equations, we get: f * λ = (150λ) / t.
– We can cancel out λ from both sides (assuming λ is non-zero): f = 150 / t.
– We are given the frequency f = 300 Hz.
– Rearranging the equation to find t: t = 150 / f.
– Substituting the value of f: t = 150 / 300 = 0.5 s.

This calculation assumes the speed of the sound wave is constant in the unknown medium. The wavelength of the sound wave in the medium is not required to find the time, as it cancels out in the calculation.

3. Which of the following statements for persons suffering from presbyopi

Which of the following statements for persons suffering from presbyopia is/are correct ?

1. They cannot distinguish colours.
2. It usually develops with ageing.
3. They wear either bi-focal lenses consisting of both concave and convex lenses or progressive lenses.

Select the answer using the code given below :

1 only

2 only

1 and 3

2 and 3

This question was previously asked in

UPSC CDS-2 – 2024

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Statement 1 is incorrect, while statements 2 and 3 are correct.

– Presbyopia is a condition that affects the eye’s ability to focus, especially on near objects. It is a natural process that occurs with ageing, typically starting around the age of 40. The eye’s lens becomes less flexible, making it harder to adjust focus. Thus, statement 2 is correct.
– Difficulty distinguishing colours is associated with colour blindness (daltonism), which is a different condition and not typically related to presbyopia. Thus, statement 1 is incorrect.
– People with presbyopia often need corrective lenses to see clearly up close. Bifocal lenses have two distinct optical powers (for distance and near vision), while progressive lenses provide a smooth transition between multiple focal lengths. These are common solutions for correcting presbyopia, often combined with other refractive errors like myopia or hyperopia. Thus, statement 3 is correct.

Presbyopia is derived from the Greek word “presbys” meaning “old man” and “ops” meaning “eye”. It is a universal physiological change. Contact lenses and refractive surgery can also be options for correcting presbyopia in some cases.

4. Which one of the following is the most appropriate reason for aircraft

Which one of the following is the most appropriate reason for aircraft being equipped with conducting tyres ?

They can transfer the charge accumulated on their surfaces during lightning

They can transfer the charge accumulated on their surfaces being rubbed by air particles

They can transfer accumulated on their surfaces due to inflight operation of several gadgets

For preventing sparks on the ground while they land

This question was previously asked in

UPSC CDS-2 – 2024

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The most appropriate reason for aircraft being equipped with conducting tyres is for preventing sparks on the ground while they land.

Aircraft build up a considerable amount of static electric charge during flight due to friction with air, dust, and precipitation. This charge needs to be safely dissipated upon landing. Conducting tyres provide a low-resistance path for this accumulated static charge to flow from the aircraft’s structure to the ground, thus neutralizing the charge gradually and preventing a sudden electrostatic discharge or spark that could ignite flammable fuel vapours near the ground.

Option B correctly identifies the source of the charge accumulation (rubbing by air particles), and conducting tyres *do* transfer this charge. However, the *reason* for this capability is the safety outcome described in option D – preventing potentially catastrophic sparks during landing. Option D is the most direct and crucial reason for the design feature.

5. Which of the following are the major missions of Indian Space Research

Which of the following are the major missions of Indian Space Research Organization in 2023 ?

1. Chandrayaan-3
2. Solar Mission Aditya-L1
3. Liquid fuel powered rockets
4. Solar powered rockets

Select the answer using the code given below :

1 and 2 only

1, 2 and 3

3 and 4 only

1, 2, 3 and 4

This question was previously asked in

UPSC CDS-2 – 2024

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Chandrayaan-3 and Solar Mission Aditya-L1 were major missions of the Indian Space Research Organization (ISRO) in 2023.

In 2023, ISRO successfully launched and executed two highly significant scientific missions: Chandrayaan-3, India’s third lunar exploration mission which achieved a historic soft landing on the Moon’s south polar region, and Aditya-L1, India’s first space-based observatory dedicated to studying the Sun from a halo orbit around the Sun-Earth Lagrangian point L1.

Options 3 (“Liquid fuel powered rockets”) and 4 (“Solar powered rockets”) refer to types of propulsion or non-existent technologies for launch vehicles, not specific missions conducted by ISRO in 2023. ISRO utilizes liquid-fueled rockets (like PSLV stages and GSLV) for its launches, but these are the means of delivery rather than the mission names themselves. Solar power is used by spacecraft in orbit for energy but not for rocket propulsion during launch.

6. Ozone hole is a region over :

Ozone hole is a region over :

the Antarctic caused mainly by CFC gases.

the Antarctic caused mainly by carbon dioxide gas.

the Arctic caused mainly by CFC gases.

the Arctic caused mainly by carbon dioxide gas.

This question was previously asked in

UPSC CDS-2 – 2024

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The ozone hole is a region over the Antarctic caused mainly by CFC gases.

The “ozone hole” refers to the dramatic thinning of the stratospheric ozone layer that occurs annually over Antarctica during the Southern Hemisphere spring (August-October). This severe depletion is primarily driven by catalytic reactions involving chlorine and bromine atoms released from synthetic ozone-depleting substances (ODS) like chlorofluorocarbons (CFCs) and halons, which accumulate in the stratosphere and are activated under the extremely cold conditions and sunlight present in the Antarctic polar vortex.

While some ozone depletion also occurs over the Arctic, it is generally less severe and variable due to different meteorological conditions. Carbon dioxide (CO₂) is a greenhouse gas that contributes to global warming but is not a direct cause of stratospheric ozone depletion; in fact, increasing greenhouse gases can even cool the stratosphere, potentially influencing ozone chemistry in complex ways.

7. The phenomenon of rainbow formation by water droplets involves :

The phenomenon of rainbow formation by water droplets involves :

single refraction of sunlight

one internal reflection of sunlight

two internal reflections of sunlight

both refraction and internal reflection of sunlight

This question was previously asked in

UPSC CDS-2 – 2024

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The phenomenon of rainbow formation by water droplets involves both refraction and internal reflection of sunlight.

A rainbow is formed when sunlight interacts with raindrops. Sunlight is first refracted (bent) as it enters the water droplet. It is then internally reflected off the back inner surface of the droplet. Finally, it is refracted again as it exits the droplet. The different wavelengths (colors) of light are refracted at slightly different angles (dispersion), separating the white light into the spectrum of colors observed in a rainbow.

A primary rainbow involves one internal reflection and results in the colors ordered from red on the outside to violet on the inside. A secondary rainbow involves two internal reflections, reversing the color order (violet on the outside, red on the inside), and is typically fainter than the primary rainbow.

8. Which one of the following heat transfers is an example of convection

Which one of the following heat transfers is an example of convection ?

Heating of food in a microwave oven

Boiling water in a pot on a gas stove

Feeling the warmth in sun

Heating a brass rod at one end and observing the temperature rise at the other end

This question was previously asked in

UPSC CDS-2 – 2024

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Boiling water in a pot on a gas stove is an example of heat transfer primarily by convection within the water.

Convection is the transfer of heat through the movement of a fluid (liquid or gas). In boiling water, heat from the stove is conducted through the pot to the water at the bottom. This heated water becomes less dense and rises, while cooler, denser water from the top sinks, creating circulating currents (convection currents) that distribute heat throughout the liquid.

Heat transfer in a microwave oven (A) is primarily through dielectric heating caused by microwave radiation exciting water molecules. Feeling warmth from the sun (C) is heat transfer by radiation through electromagnetic waves. Heating a brass rod (D) involves heat transfer by conduction through the solid material from the hotter end to the cooler end via molecular vibrations and free electron movement.

9. X-rays can be used to : inspect welded joints between two metal part

X-rays can be used to :

inspect welded joints between two metal parts of a machine.
study structure of crystals.

Select the answer using the code given below :

1 only

2 only

Both 1 and 2

Neither 1 nor 2

This question was previously asked in

UPSC CDS-2 – 2024

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Both inspecting welded joints between two metal parts of a machine and studying the structure of crystals can be done using X-rays.

X-ray radiography is a well-established Non-Destructive Testing (NDT) technique used to inspect internal structures for defects, such as detecting cracks, voids, or porosity in welded joints or castings. X-ray Diffraction (XRD) is a fundamental technique in materials science used to study the atomic and molecular structure of crystalline solids by analyzing the diffraction pattern produced when X-rays interact with the crystal lattice.

X-rays have numerous other applications, including medical imaging (radiography, CT scans), security screening, and X-ray fluorescence (XRF) spectroscopy for elemental analysis.

10. Which one among the following is used in bleaching of paper ?

Which one among the following is used in bleaching of paper ?

Chloride

Chlorobenzene

Ammonium chloride

Hydrochloric acid

This question was previously asked in

UPSC CDS-2 – 2024

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Chloride (referring to chlorine-based compounds) is used in the bleaching of paper.

Bleaching of paper pulp is primarily done using oxidizing agents to remove lignin and whiten the pulp. Historically, elemental chlorine (Cl₂) was used, but it has largely been replaced by more environmentally friendly chlorine-based compounds like chlorine dioxide (ClO₂) or processes using oxygen, hydrogen peroxide, or ozone. Among the given options, “Chloride” is the most general term that points towards the use of chlorine-based bleaching agents.

Options B (Chlorobenzene) is an organic solvent and chemical intermediate, not a paper bleach. Option C (Ammonium chloride) is a salt used in various applications but not paper bleaching. Option D (Hydrochloric acid) is a strong acid, used in some industrial processes but not as the primary bleaching agent for paper pulp.