UPSC NDA-2 Archives

21. Which one of the following statements is correct for a plane mirror?

Which one of the following statements is correct for a plane mirror?

Its focal length is zero.

The size of the image of an object placed in front of the mirror is slightly less than that of the object.

The image is virtual, erect and laterally inverted.

Its focal length is 200 cm.

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UPSC NDA-2 – 2018

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The correct statement for a plane mirror is C) The image is virtual, erect and laterally inverted.

A plane mirror forms a virtual image, which means it appears to be behind the mirror and cannot be projected onto a screen. This image is always erect (upright) relative to the object. It is also laterally inverted, meaning the left side of the object appears as the right side of the image, and vice versa.

Other properties of the image formed by a plane mirror include:
– The size of the image is equal to the size of the object.
– The distance of the image behind the mirror is equal to the distance of the object in front of the mirror.
– The focal length of a plane mirror is considered to be infinite.

22. Which one of the following is not a process of chemical weathering?

Which one of the following is not a process of chemical weathering?

Solution

Carbonation

Oxidation

Exfoliation

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The correct answer is D) Exfoliation.

Exfoliation is a type of physical weathering process, not chemical weathering. Chemical weathering involves the decomposition of rocks through chemical reactions, such as solution, carbonation, and oxidation.

Chemical weathering processes include Solution (minerals dissolving in water), Carbonation (reaction with carbonic acid, often formed from CO2 in water), Oxidation (reaction with oxygen, e.g., rusting), Hydration (addition of water to mineral structures), and Hydrolysis (reaction of water with minerals to form new compounds). Physical weathering processes, like exfoliation, involve the breakdown of rocks into smaller pieces without changing their chemical composition. Exfoliation is the process where outer layers of rock peel off due to pressure release or thermal expansion/contraction.

23. Steppe (temperate continental) climate is not experienced in which one

Steppe (temperate continental) climate is not experienced in which one of the following places?

Pretoria

Saskatchewan

Perth

Buenos Aires

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Steppe (temperate continental) climate is not experienced in Perth.

– Steppe climate (often classified as BSk or BSh in Koppen depending on temperature, but the question specifies “temperate continental”) is a semi-arid climate characterized by grasslands, intermediate in precipitation between desert and humid climates. It is typically found in continental interiors or rain shadow areas of mid-latitudes.
– Saskatchewan, Canada, is part of the Great Plains/Prairies and experiences significant areas with Cold Semi-arid (BSk) or Humid Continental (Dfb) climates, including vast grasslands indicative of steppe conditions.
– Buenos Aires, Argentina, is in the Pampas region, which predominantly has a Humid Subtropical climate (Cfa), although some western parts border on semi-arid conditions.
– Pretoria, South Africa, located on the Highveld, has a subtropical highland climate (Cwb or Cwa) or a high-altitude semi-arid climate (BShw), characterized by dry winters and wet summers. While bordering on semi-arid conditions, it is not a classic mid-latitude continental steppe.
– Perth, Western Australia, has a Mediterranean climate (Cs), characterized by hot, dry summers and mild, wet winters. This distinct seasonal rainfall pattern is different from the less extreme seasonal precipitation typical of steppe climates.
– Among the given options, Perth’s climate is the most distinctly different from a steppe climate.

– Classic examples of temperate steppe regions include the Great Plains of North America, the Eurasian Steppe, and the Pampas of Argentina.
– Mediterranean climates (Cs) are typically found on the western sides of continents between roughly 30° and 45° latitude.

24. Which one of the following is the correct descending order of Indian S

Which one of the following is the correct descending order of Indian States in terms of sex ratio as per Census 2011?

Mizoram—Manipur—Tripura—Meghalaya

Tripura—Manipur—Meghalaya—Mizoram

Meghalaya—Manipur—Mizoram—Tripura

Manipur—Meghalaya—Tripura—Mizoram

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UPSC NDA-2 – 2018

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According to Census 2011, the correct descending order of the given Indian States in terms of sex ratio is Meghalaya—Manipur—Mizoram—Tripura.

– Sex ratio is defined as the number of females per 1000 males in a population.
– According to Census 2011 data for the given states:
– Meghalaya: 989
– Manipur: 985
– Mizoram: 976
– Tripura: 960
– Arranging these states in descending order of sex ratio (highest to lowest): 989 (Meghalaya) > 985 (Manipur) > 976 (Mizoram) > 960 (Tripura).
– The correct order is Meghalaya—Manipur—Mizoram—Tripura.

– Kerala had the highest sex ratio among Indian states in Census 2011 (1084), while Haryana had the lowest (879).
– The national average sex ratio in India according to Census 2011 was 943.

25. 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 (Railway Zone)	List-II (Headquarters)
A. West Central	1. Jabalpur
B. South East Central	2. Gorakhpur
C. East Central	3. Bilaspur
D. North Eastern	4. Hajipur

Code :

A-2, B-3, C-4, D-1

A-1, B-4, C-3, D-2

A-2, B-4, C-3, D-1

A-1, B-3, C-4, D-2

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UPSC NDA-2 – 2018

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The correct match between List-I (Railway Zone) and List-II (Headquarters) is A-1, B-3, C-4, D-2.

– Indian Railways is divided into various zones, each having a designated headquarters.
– West Central Railway has its headquarters in Jabalpur.
– South East Central Railway has its headquarters in Bilaspur.
– East Central Railway has its headquarters in Hajipur.
– North Eastern Railway has its headquarters in Gorakhpur.
– Matching the zones to their headquarters: A-1 (West Central – Jabalpur), B-3 (South East Central – Bilaspur), C-4 (East Central – Hajipur), D-2 (North Eastern – Gorakhpur).

– As of 2023, Indian Railways has 18 zones and 73 divisions.
– Understanding the headquarters of major railway zones is relevant for general knowledge about India’s infrastructure.

26. 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 (Koppen’s Climatic Type)	List-II (Letter Code)
A. Tropical wet	1. Af
B. Mid-latitude desert	2. Cs
C. Mediterranean	3. Df
D. Humid continental	4. BWk

Code :

A-1, B-4, C-2, D-3

A-1, B-2, C-4, D-3

A-3, B-2, C-4, D-1

A-3, B-4, C-2, D-1

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UPSC NDA-2 – 2018

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The correct match between List-I (Koppen’s Climatic Type) and List-II (Letter Code) is A-1, B-4, C-2, D-3.

– Koppen’s climate classification uses letter codes to represent different climate types based primarily on temperature and precipitation characteristics.
– A. Tropical wet climate is characterized by consistently high temperatures and heavy rainfall throughout the year, designated by the code Af (A: Tropical, f: fully humid).
– B. Mid-latitude desert is an arid climate type found in mid-latitudes, often experiencing cold winters. The code BWk represents Arid (B), Desert (W), and Cold (k).
– C. Mediterranean climate is characterized by hot, dry summers and mild, wet winters. The code is Cs (C: Temperate, s: dry summer).
– D. Humid continental climate is found in mid-latitudes of continents, characterized by large seasonal temperature variations with warm to hot summers and cold winters, and precipitation throughout the year. The code is Df (D: Continental, f: fully humid).
– Matching the types to codes gives: A-1 (Af), B-4 (BWk), C-2 (Cs), D-3 (Df).

– The first letter of the Koppen code usually indicates the main climate group (A: Tropical, B: Arid, C: Temperate, D: Continental, E: Polar).
– Subsequent letters denote precipitation patterns (f: fully humid, w: dry winter, s: dry summer, m: monsoon) and temperature characteristics (a: hot summer, b: warm summer, c: cool summer, d: extremely cold winter, h: hot arid, k: cold arid).

27. Which one of the following greenhouse gases is in largest concentratio

Which one of the following greenhouse gases is in largest concentration in the atmosphere?

Chlorofluorocarbon

Nitrous oxide

Carbon dioxide

Methane

This question was previously asked in

UPSC NDA-2 – 2018

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Among the given options, Carbon dioxide is in the largest concentration in the atmosphere.

– Greenhouse gases trap heat in the Earth’s atmosphere, contributing to the greenhouse effect.
– Common greenhouse gases include water vapor (H₂O), carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), ozone (O₃), and chlorofluorocarbons (CFCs).
– While water vapor is the most abundant greenhouse gas overall, its concentration is highly variable and often considered separately when discussing anthropogenic emissions.
– Among the options listed (excluding water vapor), carbon dioxide (CO₂) has by far the highest concentration in the Earth’s atmosphere. Its concentration is currently over 400 parts per million (ppm).
– Methane (CH₄) concentration is around 1.9 ppm, Nitrous oxide (N₂O) is around 0.34 ppm, and Chlorofluorocarbons (CFCs) are present in much lower concentrations (parts per billion or trillion).

– The radiative efficiency (global warming potential) and atmospheric lifetime vary significantly among greenhouse gases. CO₂ has a relatively low radiative efficiency compared to CH₄ or N₂O, but its high concentration and long atmospheric lifetime make it the largest contributor to anthropogenic climate change.
– The concentrations of these gases are monitored globally by various scientific bodies.

28. The refractive indices of two media are denoted by n 1 and n 2 and t

The refractive indices of two media are denoted by n₁ and n₂ and the velocities of light in these two media are respectively v₁ and v₂. If n₂ / n₁ is 1.5, which one of the following statements is correct?

v1 is 1.5 times v2.

v2 is 1.5 times v1.

v1 is equal to v2.

v1 is 3 times v2.

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The correct statement is that v₁ is 1.5 times v₂.

– The refractive index (n) of a medium is defined as the ratio of the speed of light in vacuum (c) to the speed of light in that medium (v). That is, n = c/v.
– For two media, we have n₁ = c/v₁ and n₂ = c/v₂.
– The given relation is n₂ / n₁ = 1.5.
– Substitute the expressions for n₁ and n₂: (c/v₂) / (c/v₁) = 1.5.
– This simplifies to (c/v₂) * (v₁/c) = v₁ / v₂ = 1.5.
– Rearranging the equation, we get v₁ = 1.5 * v₂.

– A higher refractive index means light travels slower in that medium.
– Since n₂/n₁ = 1.5 > 1, it means n₂ > n₁. Therefore, light travels slower in medium 2 (v₂) than in medium 1 (v₁).
– The relationship v₁ = 1.5 v₂ confirms that v₁ is greater than v₂.

29. The coefficient of areal expansion of a material is 1•6×10⁻⁵ K⁻¹. Whic

The coefficient of areal expansion of a material is 1•6×10⁻⁵ K⁻¹. Which one of the following gives the value of coefficient of volume expansion of this material?

0•8×10⁻⁵ K⁻¹

2•4×10⁻⁵ K⁻¹

3•2×10⁻⁵ K⁻¹

4•8×10⁻⁵ K⁻¹

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The value of the coefficient of volume expansion of this material is 2.4×10⁻⁵ K⁻¹.

– For an isotropic solid material, the coefficients of linear expansion (α), areal expansion (β), and volume expansion (γ) are related.
– The relationship is approximately β ≈ 2α and γ ≈ 3α.
– From these relations, we can derive the relationship between the coefficient of areal expansion (β) and the coefficient of volume expansion (γ): γ = (3/2)β.
– Given coefficient of areal expansion β = 1.6 × 10⁻⁵ K⁻¹.
– Substitute the value into the formula: γ = (3/2) * (1.6 × 10⁻⁵ K⁻¹).
– γ = 1.5 * 1.6 × 10⁻⁵ K⁻¹ = 2.4 × 10⁻⁵ K⁻¹.

– These relationships (β=2α, γ=3α) are valid for small changes in temperature and for isotropic materials (materials with the same properties in all directions).
– Linear expansion refers to the change in length, areal expansion to the change in area, and volume expansion to the change in volume per unit change in temperature.

30. A ball is released from rest and rolls down an inclined plane, as show

A ball is released from rest and rolls down an inclined plane, as shown in the following figure, requiring 4 s to cover a distance of 100 cm along the plane :
Which one of the following is the correct value of angle θ that the plane makes with the horizontal? (g = 1000 cm/s²)

θ = sin⁻¹ (1/9•8)

θ = sin⁻¹ (1/20)

θ = sin⁻¹ (1/80)

θ = sin⁻¹ (1/100)

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The correct value of angle θ that the plane makes with the horizontal is sin⁻¹ (1/80).

– The ball is released from rest, so initial velocity u = 0.
– The distance covered along the plane is s = 100 cm in time t = 4 s.
– The motion along the inclined plane is uniformly accelerated. The formula for distance is s = ut + (1/2)at².
– Substitute the values: 100 cm = (0)(4 s) + (1/2)a(4 s)².
– 100 = (1/2)a(16) => 100 = 8a.
– The acceleration down the inclined plane is a = 100 / 8 = 12.5 cm/s².
– The acceleration of an object rolling down an inclined plane (without slipping, but here it’s just about acceleration along the plane component of gravity) is a = g sin θ, where g is the acceleration due to gravity and θ is the angle of inclination.
– Given g = 1000 cm/s².
– So, 12.5 = 1000 sin θ.
– sin θ = 12.5 / 1000 = 125 / 10000 = 1 / 80.
– θ = sin⁻¹ (1/80).

– The acceleration due to gravity along an inclined plane is g sin θ, and perpendicular to the plane is g cos θ. The net force along the plane determines the acceleration.
– The value of g is given as 1000 cm/s², which is equivalent to 10 m/s².