UPSC NDA-1

21. The European Space Agency (ESA) successfully landed a spacecraft on a

The European Space Agency (ESA) successfully landed a spacecraft on a speeding comet that lies 310 million miles away from Earth. As a result, the scientists may find out

[amp_mcq option1=”the age of the Sun” option2=”the age of the Universe” option3=”new fundamental atomic particles” option4=”the role of the comets in bringing organic matter and water to Earth” correct=”option4″]

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The European Space Agency’s (ESA) Rosetta mission, which included the Philae lander, successfully landed on comet 67P/Churyumov–Gerasimenko in November 2014. Comets are believed to be pristine remnants from the formation of the solar system, preserving material from that era. A major scientific objective of studying comets is to understand their composition, including water and organic molecules, and their potential role in delivering these crucial building blocks to early Earth, which could have been significant for the origin of life.
Comet missions like Rosetta aim to study the composition of comets to understand the early solar system and their potential role in delivering water and organic matter to Earth.
The Rosetta mission orbited the comet for over two years, studying it extensively, while Philae provided data from the surface, although its power source was limited due to landing in a shaded location.

22. Which of the following country/countries successfully inserted a space

Which of the following country/countries successfully inserted a spacecraft into Mars’ orbit by maiden attempt ?

[amp_mcq option1=”USA” option2=”USA and Russia” option3=”India” option4=”China” correct=”option3″]

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India’s Mars Orbiter Mission (MOM), also known as Mangalyaan, successfully inserted a spacecraft into Mars’ orbit on September 24, 2014. This was India’s first interplanetary mission and it achieved orbit insertion on its very first attempt, a feat not accomplished by any other country or space agency before (USA, Soviet Union/Russia, and Europe had previous attempts, some successful, some not, before achieving orbit insertion).
India is the first country to successfully place a spacecraft into Mars orbit on its maiden attempt.
The Mars Orbiter Mission was a technology demonstrator project but also carried scientific payloads to study the Martian atmosphere and surface. Its success made India the fourth entity (after NASA, Soviet space program, and ESA) to reach Mars and the first in Asia.

23. The radius of the Moon is about one-fourth that of the Earth and accel

The radius of the Moon is about one-fourth that of the Earth and acceleration due to gravity on the Moon is about one-sixth that on the Earth. From this, we can conclude that the ratio of the mass of Earth to the mass of the Moon is about

[amp_mcq option1=”10″ option2=”100″ option3=”1,000″ option4=”10,000″ correct=”option2″]

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The acceleration due to gravity (g) on a celestial body with mass M and radius R is given by the formula g = GM/R², where G is the gravitational constant. We are given that the radius of the Moon (Rm) is about one-fourth that of the Earth (Re), i.e., Rm ≈ Re/4. We are also given that the acceleration due to gravity on the Moon (gm) is about one-sixth that on the Earth (ge), i.e., gm ≈ ge/6.
From g = GM/R², we can write M = gR²/G.
The ratio of the mass of Earth (Me) to the mass of the Moon (Mm) is:
Me/Mm = (ge * Re² / G) / (gm * Rm² / G)
Me/Mm = (ge/gm) * (Re/Rm)²
Substitute the given ratios: ge/gm ≈ 6 and Re/Rm ≈ 4.
Me/Mm ≈ 6 * (4)² = 6 * 16 = 96.
Among the options, 96 is closest to 100.
The ratio of masses can be calculated using the relationship between acceleration due to gravity, mass, and radius (g = GM/R²).
The actual ratio of Earth’s mass to Moon’s mass is approximately 81.3, so the given approximate values lead to a result (96) that is closest to 100, indicating the question uses approximate figures typical for simplified calculations.

24. Perspiration cools the body because

Perspiration cools the body because

[amp_mcq option1=”presence of water on the skin is cooling” option2=”evaporation requires latent heat” option3=”water has a high specific heat” option4=”water is a poor conductor of heat” correct=”option2″]

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Perspiration cools the body through the process of evaporation. When sweat (water) evaporates from the skin surface, it changes from a liquid to a gas. This phase change requires energy, which is absorbed from the skin and underlying tissues. This energy absorbed is known as the latent heat of vaporization. By absorbing heat from the body, the evaporation process effectively cools the skin and helps regulate body temperature.
Evaporation of sweat cools the body because it requires latent heat, which is drawn from the body itself.
Factors like humidity affect the rate of evaporation. In high humidity, evaporation is slower, making it harder for the body to cool down effectively through sweating.

25. Thermal conductivity of aluminium, copper and stainless steel increase

Thermal conductivity of aluminium, copper and stainless steel increases in the order

[amp_mcq option1=”Copper < Aluminium < Stainless Steel" option2="Stainless Steel < Aluminium < Copper" option3="Aluminium < Copper < Stainless Steel" option4="Copper < Stainless Steel < Aluminium" correct="option2"]

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Thermal conductivity is a measure of a material’s ability to conduct heat. Generally, pure metals are good thermal conductors, while alloys and non-metals are poorer conductors. Among the given options, copper is an excellent thermal conductor, aluminium is also good but less so than copper, and stainless steel (an alloy of iron, chromium, nickel, etc.) is a relatively poor conductor compared to pure metals. Typical thermal conductivity values (in W/m·K) are approximately: Copper ≈ 400, Aluminium ≈ 205, Stainless Steel ≈ 15-20. Therefore, the order of increasing thermal conductivity is Stainless Steel < Aluminium < Copper.
Different materials have different thermal conductivity values; pure metals like copper and aluminium are typically better conductors than alloys like stainless steel.
Good thermal conductors are used in applications like heat sinks and cooking utensils, while poor conductors (thermal insulators) are used for insulation purposes.

26. The Sun is observed to be reddish when it is near the horizon, i.e., i

The Sun is observed to be reddish when it is near the horizon, i.e., in the morning and the evening. This is because

[amp_mcq option1=”red light is least scattered by atmosphere” option2=”red light is most scattered by atmosphere” option3=”it is the colour of the Sun in the morning and evening” option4=”Earth’s atmosphere emits red light” correct=”option1″]

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The scattering of sunlight by particles in the atmosphere is described by Rayleigh scattering. According to Rayleigh scattering, the intensity of scattered light is inversely proportional to the fourth power of its wavelength (I ∝ 1/λ⁴). This means shorter wavelengths (like blue and violet) are scattered much more effectively than longer wavelengths (like red and orange). When the Sun is near the horizon, sunlight travels through a much greater thickness of the atmosphere. Most of the shorter-wavelength blue light is scattered away from the line of sight, leaving the longer-wavelength red and orange light to reach the observer, making the Sun appear reddish.
The reddish appearance of the Sun at sunrise and sunset is due to the atmospheric scattering of light, specifically the preferential scattering of shorter wavelengths.
The blue colour of the sky during the day is also a result of Rayleigh scattering, where the abundant blue light from the Sun is scattered in all directions across the sky.

27. ‘Lub-dup’ sound is produced due to action of

‘Lub-dup’ sound is produced due to action of

[amp_mcq option1=”Large intestine” option2=”Lungs” option3=”Heart” option4=”Oesophagus” correct=”option3″]

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The ‘lub-dup’ sounds are characteristic heart sounds. The ‘lub’ sound occurs during systole when the atrioventricular valves (mitral and tricuspid) close. The ‘dup’ sound occurs during diastole when the semilunar valves (aortic and pulmonary) close. These sounds are produced by the vibrations of the valves, heart walls, and blood flow.
The ‘lub-dup’ sounds are associated with the closure of heart valves during the cardiac cycle.
These sounds can be heard using a stethoscope. Abnormal heart sounds, called murmurs, can indicate underlying issues with valve function or blood flow.

28. Precursor of which one of the following vitamins comes from β-carotene

Precursor of which one of the following vitamins comes from β-carotene ?

[amp_mcq option1=”Vitamin A” option2=”Vitamin C” option3=”Vitamin D” option4=”Vitamin K” correct=”option1″]

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Beta-carotene (β-carotene) is a red-orange pigment found in plants and fruits, particularly carrots and other colorful vegetables. It is a carotenoid and is a precursor to Vitamin A. The human body converts beta-carotene into retinol, which is a form of Vitamin A. This conversion primarily occurs in the liver. Vitamins C, D, and K have different precursors or are synthesized differently (e.g., Vitamin D synthesized in the skin upon sunlight exposure).
Beta-carotene is a carotenoid pigment found in plants that the body can convert into Vitamin A.
Vitamin A is essential for vision, immune function, reproduction, and cell growth. Other carotenoids like alpha-carotene and beta-cryptoxanthin can also be converted to Vitamin A, but beta-carotene is the most efficient precursor. Vitamin C is an ascorbic acid. Vitamin D is synthesized in the skin from cholesterol derivatives upon UV exposure. Vitamin K is involved in blood clotting and bone metabolism and is synthesized by gut bacteria or obtained from leafy greens.

29. The concept of demographic transition provides a model for

The concept of demographic transition provides a model for

[amp_mcq option1=”analyzing government responses to changing pattern of population growth” option2=”explaining major patterns of global population movement throughout the history” option3=”analyzing spatial variations in the distribution, growth and movement of population over time” option4=”examining the relationship between economic development and natural population change” correct=”option4″]

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The Demographic Transition Model (DTM) describes the historical shift in birth rates and death rates as a country or region develops from a pre-industrial to an industrialized economic system. It typically outlines four or five stages showing how changes in economic development are associated with changes in natural population change (births minus deaths). It does not primarily focus on government responses, population movement (migration), or spatial variations, although these can be related. Its core purpose is to explain the link between development and population growth patterns.
The Demographic Transition Model explains how population growth rates change as societies undergo economic development, specifically linking birth and death rates to modernization.
The DTM proposes that countries pass through stages: Stage 1 (High birth and death rates, low growth), Stage 2 (Falling death rates, high birth rates, rapid growth), Stage 3 (Falling birth rates, slowing growth), Stage 4 (Low birth and death rates, stable or slow growth), and sometimes Stage 5 (Birth rate below death rate, population decline).

30. Match List I with List II and select the correct answer using the code

Match List I with List II and select the correct answer using the code given below the Lists :

List I
(Cloud)		 List II
(Characteristic)
A. Cirrus 1. Rain giving
B. Stratus 2. Feathery appearance
C. Nimbus 3. Vertically growing
D. Cumulus 4. Horizontally spreading

[amp_mcq option1=”A-3, B-1, C-4, D-2″ option2=”A-3, B-4, C-1, D-2″ option3=”A-2, B-4, C-1, D-3″ option4=”A-2, B-1, C-4, D-3″ correct=”option3″]

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Let’s match the cloud types with their characteristics:
A. Cirrus: Cirrus clouds are high-altitude clouds composed of ice crystals. They are thin, wispy, and have a feathery appearance. So, Cirrus matches with Feathery appearance (2).
B. Stratus: Stratus clouds are low-level, flat, and horizontally extended clouds that often cover the sky like a blanket. So, Stratus matches with Horizontally spreading (4).
C. Nimbus: Nimbus is a prefix or suffix indicating a cloud that produces precipitation (rain, snow, etc.). Nimbostratus and Cumulonimbus are examples of rain-giving clouds. So, Nimbus matches with Rain giving (1).
D. Cumulus: Cumulus clouds are puffy, white clouds with flat bases and rounded tops. They often develop vertically. Large, vertically developed cumulus clouds can become cumulonimbus clouds. So, Cumulus matches with Vertically growing (3).
Putting it together: A-2, B-4, C-1, D-3. This matches option C.
Clouds are classified based on their altitude and appearance. Cirrus are high and feathery, Stratus are low and layered, Nimbus indicates rain, and Cumulus are puffy and grow vertically.
The main cloud types are Cirrus (high, wispy), Cumulus (puffy, vertical), Stratus (layered, horizontal), and Nimbus (rain-bearing). Combinations like Cirrocumulus, Cirrostratus, Altocumulus (mid-level puffy), Altostratus (mid-level layered), Cumulonimbus (large vertical rain cloud), and Nimbostratus (low/mid-level rain cloud) also exist.
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