UPSC CAPF Archives

11. Which one of the following statements about the solstices, an event th

Which one of the following statements about the solstices, an event that occurs when the Sun appears to reach most northerly or southerly, is correct ?

The winter solstice takes place on June 21 in both the northern and southern hemispheres

The winter solstice takes place on December 21 in both the northern and southern hemispheres

The summer solstice occurs in northern hemisphere on June 21 and on December 21 in southern hemisphere

The summer solstice occurs in northern hemisphere on December 21 and on June 21 in southern hemisphere

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UPSC CAPF – 2024

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Solstices are astronomical events that occur twice a year, marking the points at which the Sun reaches its highest or lowest point in the sky at noon, depending on the hemisphere. This is due to the tilt of the Earth’s axis relative to its orbital plane. The summer solstice occurs around June 20 or 21 in the Northern Hemisphere when the North Pole is tilted towards the Sun, resulting in the longest day of the year. On this same date, it is the winter solstice in the Southern Hemisphere, with the shortest day. Conversely, the winter solstice in the Northern Hemisphere occurs around December 21 or 22 when the North Pole is tilted away from the Sun, marking the shortest day. On this date, it is the summer solstice in the Southern Hemisphere. Therefore, the summer solstice occurs in the Northern Hemisphere on June 21 (approximately) and in the Southern Hemisphere on December 21 (approximately).

Solstices mark the maximum axial tilt of the Earth towards or away from the Sun, leading to the longest and shortest days of the year in the respective hemispheres. The solstices in the Northern and Southern Hemispheres are six months apart.

The dates of the solstices can vary by a day or two each year due to the Earth’s elliptical orbit and the presence of leap years. The other key seasonal markers are the equinoxes (vernal/spring and autumnal), which occur around March 20 and September 22, when the tilt is neither towards nor away from the Sun, resulting in approximately equal day and night length globally.

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12. Which one of the following heat transfer mechanism does NOT require a

Which one of the following heat transfer mechanism does NOT require a medium ?

Conduction

Convection

Radiation

Collision

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UPSC CAPF – 2024

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Heat transfer occurs through three primary mechanisms: conduction, convection, and radiation. Conduction is the transfer of heat through direct contact and molecular vibrations within a material; it requires a medium (solid, liquid, or gas). Convection is the transfer of heat through the bulk movement of a fluid (liquid or gas); it requires a medium that can flow. Radiation is the transfer of heat through electromagnetic waves, such as infrared radiation. These waves can travel through a vacuum (like space) and do not require a physical medium to transfer energy. Collision is not a distinct primary heat transfer mechanism; energy transfer through molecular collisions is the basis of conduction and part of convection at the molecular level. Therefore, radiation is the only mechanism listed that does not require a medium.

Conduction and convection require a medium for heat transfer, while radiation does not. Heat from the Sun reaches Earth through radiation across the vacuum of space.

Examples: Conduction heats the handle of a metal spoon in hot soup. Convection heats water in a pot as warmer water rises and cooler water sinks. Radiation is felt as warmth from a fire or the sun. All three mechanisms can occur simultaneously in many situations, but one often dominates depending on the conditions.

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13. Which one of the following statements correctly defines PM1 particles

Which one of the following statements correctly defines PM1 particles in air ?

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These are suspended particles of diameter more than 10 micron

These are the particles that are filtered by the nose during respiration

These are extreme fine particles of diameter less than 1 micron

These are coarse particles that penetrate directly through the lungs into the bloodstream

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UPSC CAPF – 2024

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PM stands for Particulate Matter, which is a mixture of solid particles and liquid droplets found in the air. The number designation (e.g., PM10, PM2.5, PM1) refers to the maximum diameter of the particles in micrometers (microns). PM1 particles are defined as extremely fine particles that have a diameter less than 1 micrometer. These are smaller than PM2.5 and PM10 particles.

PM classification is based on the aerodynamic diameter of airborne particulate matter. PM1 < 1 µm, PM2.5 < 2.5 µm, PM10 < 10 µm. Smaller particles can penetrate deeper into the respiratory system.

PM1 particles are considered among the most harmful air pollutants because their small size allows them to be inhaled deeply into the lungs and potentially enter the bloodstream. They are often associated with combustion processes (vehicle exhaust, industrial emissions, power plants) and can contribute to respiratory and cardiovascular diseases.

14. A canon shoots a ball upwards with an initial speed of 100 m/s. The to

A canon shoots a ball upwards with an initial speed of 100 m/s. The total time of flight of the ball is 20 s before it hits the ground. The ball looses 70% of its speed after hitting the ground. Which among the following is the correct height that the ball will bounce up after its first bounce? (g=10 m/s²)

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100 m

70 m

50 m

45 m

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This question was previously asked in

UPSC CAPF – 2024

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The ball is shot upwards with an initial speed of 100 m/s. In vertical motion under gravity (g=10 m/s²), the time taken to reach the maximum height is given by t_up = u/g = 100/10 = 10 s. The time taken to fall back to the ground from the maximum height is also 10 s. The total time of flight before the first bounce is t_up + t_down = 10 + 10 = 20 s, which matches the given information. The speed of the ball just before hitting the ground after falling from its peak height is equal to its initial projection speed, which is 100 m/s (downwards). After hitting the ground, the ball loses 70% of its speed. So, the speed after the first bounce is (100% – 70%) of 100 m/s = 30% of 100 m/s = 0.30 * 100 m/s = 30 m/s (upwards). To find the height the ball bounces up, we use the equation v² = u² + 2as, where the final velocity at the peak height is v=0, the initial velocity after bounce is u=30 m/s, and the acceleration is a=-g=-10 m/s². So, 0² = 30² + 2 * (-10) * h. This simplifies to 0 = 900 – 20h, so 20h = 900, which gives h = 900/20 = 45 meters.

Understanding projectile motion under gravity, calculating time of flight, speed before impact, calculating speed after an inelastic collision (loss of speed), and calculating the maximum height reached with a new initial velocity.

The collision with the ground is inelastic as the ball loses speed. The coefficient of restitution (e) for this bounce would be the ratio of the speed after bounce to the speed before bounce, i.e., e = 30/100 = 0.3. The maximum height reached after a bounce with speed v is given by h = v² / (2g).

15. Which one of the following statements with regard to greenhouse effect

Which one of the following statements with regard to greenhouse effect is correct?

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It can take place inside a glass chamber where no radiation can pass into it or pass back through it

It can take place inside a glass chamber where long wavelength infrared radiation can pass through into it and short wavelength infrared radiation cannot pass back through it

It can take place inside a glass chamber where short wavelength infrared radiation can pass through and long wavelength infrared radiation cannot pass through it

It can take place inside a glass chamber where all infrared radiation can pass into it or pass back through it

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This question was previously asked in

UPSC CAPF – 2024

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The greenhouse effect in a simplified model, like a glass chamber (or the Earth’s atmosphere), works because the medium is transparent to incoming radiation but opaque or less transparent to outgoing radiation. The Sun emits radiation primarily in the visible and short-wavelength infrared range, which passes through glass. This radiation heats the interior surface. The heated surface then re-emits radiation in the longer wavelength infrared range. Glass (and greenhouse gases in the atmosphere) absorb or reflect this longer wavelength infrared radiation, trapping heat inside. Therefore, short wavelength radiation passes in, and long wavelength radiation cannot easily pass out.

The core principle of the greenhouse effect is the differential transparency of the trapping medium (glass or atmosphere) to incoming short-wavelength radiation and outgoing long-wavelength infrared radiation.

In the Earth’s atmosphere, greenhouse gases like carbon dioxide, methane, and water vapor play the role of the glass, being largely transparent to incoming solar radiation but absorbing and re-emitting outgoing infrared radiation, warming the planet. A glass greenhouse traps heat not only due to this radiative effect but also by preventing convective heat loss. However, the term “greenhouse effect” applied to the atmosphere primarily refers to the radiative trapping mechanism.

16. In Sun-Earth system, the distance between Lagrange points L2 and L3 is

In Sun-Earth system, the distance between Lagrange points L2 and L3 is about

15 lakh kilometre

30 lakh kilometre

16 crore kilometre

32 crore kilometre

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UPSC CAPF – 2024

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Lagrange points L1, L2, and L3 for the Sun-Earth system lie on the line connecting the Sun and the Earth. L1 and L2 are located approximately 1.5 million kilometers (or 0.01 AU) from Earth. L1 is between the Sun and Earth, and L2 is beyond Earth away from the Sun. L3 is on the opposite side of the Sun from Earth, roughly at the same distance from the Sun as Earth (approx 1 AU). The distance between L2 and L3 is approximately the distance from L2 to Earth (~1.5M km) + the distance from Earth to the Sun (~150M km) + the distance from the Sun to L3 (~150M km). This sum is approximately 1.5M km + 150M km + 150M km = 301.5M km. This is equivalent to 30.15 crore kilometers. Option D, 32 crore kilometre, is the closest value among the choices.

– L1, L2, and L3 are collinear Lagrange points in a two-body system.
– For the Sun-Earth system, L1 and L2 are about 1.5 million km from Earth.
– L3 is roughly 1 AU (approx 150 million km) from the Sun, on the opposite side of Earth.
– The distance between L2 and L3 is approximately L2-Earth distance + Earth-Sun distance + Sun-L3 distance.

While L3 is roughly 1 AU from the Sun, its exact location is slightly closer or farther depending on the mass distribution and other orbital parameters, but approximately 1 AU. The total distance L2 to L3 is therefore approximately 0.01 AU + 1 AU + 1 AU = 2.01 AU. Since 1 AU is about 150 million km, 2.01 AU is about 301.5 million km (30.15 crore km). Option D (32 crore km) is the best fit among the given choices.

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17. Which one among the following has largest energy per photon ?

Which one among the following has largest energy per photon ?

X-ray

Ultra-violet ray

Visible-ray

Infra-red ray

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UPSC CAPF – 2024

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The energy of a photon is directly proportional to its frequency. In the electromagnetic spectrum, energy increases as frequency increases and wavelength decreases. Among the given options, X-rays have the highest frequency (and shortest wavelength), followed by Ultra-violet rays, Visible rays, and Infra-red rays.

– The relationship between photon energy (E), Planck’s constant (h), frequency (f), speed of light (c), and wavelength (λ) is given by E = hf = hc/λ.
– Higher frequency or shorter wavelength corresponds to higher photon energy.
– The order of electromagnetic radiation in increasing frequency (and thus increasing energy per photon) is: Radio, Microwave, Infrared, Visible, Ultraviolet, X-ray, Gamma ray.

Visible light occupies a small portion of the spectrum. Infrared is below visible light in frequency, and Ultraviolet, X-rays, and Gamma rays are above visible light in frequency. X-rays are high-energy electromagnetic radiation capable of penetrating various materials, widely used in medical imaging and security screening.

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18. Consider the following: 1. MPEG 2. P*64 3. Indeo Which of the abo

Consider the following:

1. MPEG
2. P*64
3. Indeo

Which of the above can be used to compress video files ?

1 and 2 only

1 and 3 only

2 and 3 only

1, 2 and 3

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UPSC CAPF – 2024

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All three listed technologies – MPEG, P*64, and Indeo – are video compression standards or codecs that can be used to compress video files.

– MPEG (Moving Picture Experts Group) is a working group that develops standards for digital video and audio compression and transmission (e.g., MPEG-1, MPEG-2, MPEG-4, H.264, H.265).
– P*64 (Px64 or H.261) was an early video coding standard developed by the ITU-T, designed for videoconferencing over ISDN lines at multiples of 64 kbit/s.
– Indeo was a family of video codecs developed by Intel, popular in the early to mid-1990s, used for video playback on personal computers.

Video compression is essential for reducing the storage space and bandwidth required for transmitting digital video. Different codecs and standards employ various algorithms (like spatial and temporal redundancy reduction) to achieve compression, often trading off file size/bandwidth with video quality.

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19. Which one among the following is NOT a non-procedural computer

Which one among the following is NOT a non-procedural computer language?

LISP

Python

Prolog

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UPSC CAPF – 2024

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Non-procedural computer languages are declarative languages that focus on describing *what* computation should be performed, rather than specifying *how* to perform it step-by-step. LISP, Prolog, and ML are typically classified as functional or logic programming languages, which are often considered non-procedural or declarative paradigms. Python, while being a multi-paradigm language, is primarily known and used as an imperative/procedural language, where instructions are executed sequentially. Therefore, Python is NOT a non-procedural computer language in the same vein as LISP, Prolog, or ML.

– Procedural languages specify a sequence of operations to change the program’s state.
– Non-procedural (or declarative) languages describe the desired result or logic without explicitly detailing the execution steps.
– LISP, Prolog, and ML represent functional or logic programming paradigms often contrasted with procedural programming.
– Python is predominantly an imperative/procedural language, although it supports aspects of object-oriented and functional programming.

LISP (List Processing) is one of the oldest functional programming languages. Prolog (Programming in Logic) is a prominent logic programming language. ML (Meta Language) is a general-purpose functional programming language. Python’s core execution model is based on executing statements sequentially, defining procedures (functions), which aligns with the procedural paradigm.

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20. Which one of the following Indian Naval Ships has recently concluded a

Which one of the following Indian Naval Ships has recently concluded a 17,000-nm trans-ocean intercontinental voyage ?

INS Tarangini

INS Mandovi

INSV Mhadei

INSV Tarini

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UPSC CAPF – 2023

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INSV Tarini is an Indian Naval Sailing Vessel known for undertaking challenging long-distance voyages. It recently concluded a notable 17,000-nm (nautical mile) trans-ocean intercontinental voyage, including participation in the Transatlantic Race 2023 and the Cape2Rio 2023 race.

– INSV Tarini is the sister vessel of INSV Mhadei.
– It is famous for circumnavigating the globe with an all-women crew (Navika Sagar Parikrama) in 2017-2018.
– The 17,000-nm voyage in 2023 involved sailing from Goa to Rio de Janeiro, then to Cascais (Portugal), and finally back to Goa, covering multiple legs across continents and oceans.

INSV Tarini and INSV Mhadei are used by the Indian Navy for ocean sailing training and expeditions, promoting maritime skills and adventure activities. These voyages highlight the capabilities of the Indian Navy and promote India’s maritime heritage.

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