UPSC NDA-2

1. Which one of the following combinations of stalactites and stalagmites

Which one of the following combinations of stalactites and stalagmites occurrences is correct?

Stalactites hang as icicles of different diameters and stalagmites hang from the floor of the caves
Stalactites hang as icicles of different diameters and stalagmites rise up from the floor of the caves
Stalactites rise up from the floor of the caves and stalagmites hang as icicles of different diameters
Stalactites hang as icicles of different diameters and stalagmites also hang as icicles of different diameters
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Stalactites are formations that hang from the ceiling of caves, typically formed by the slow dripping of mineral-rich water, often appearing like icicles. Stalagmites are formations that rise up from the floor of caves, formed by the accumulation of material from the dripping water from above.
The distinction between stalactites (hanging) and stalagmites (rising) is a common geological concept.
These formations are types of speleothems, usually found in limestone caves, formed by the deposition of calcium carbonate dissolved in water.

2. Which one of the following statements is not correct?

Which one of the following statements is not correct?

Conduction can occur easily in solids, less easily in liquids but hardly at all in gases
Heat energy is carried by moving particles in a convection current
Heat energy is carried by electromagnetic waves in radiation
The temperature at which a solid changes into a liquid is called the boiling point
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The statement “The temperature at which a solid changes into a liquid is called the boiling point” is not correct. The temperature at which a solid changes into a liquid is called the melting point (or fusion point). The boiling point is the temperature at which a liquid changes into a gas.
This question tests knowledge of basic heat transfer mechanisms and phase change terminology.
Conduction is the transfer of heat through direct contact, most effective in solids. Convection is the transfer of heat through the movement of fluids (liquids or gases). Radiation is the transfer of heat through electromagnetic waves, which can occur even in a vacuum.

3. Which one of the following is the SI unit of the thermal conductivity

Which one of the following is the SI unit of the thermal conductivity of a material?

Wm'K~!
Wm/K
WmYK™?
Js'm'K
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The correct answer is A) Wm’K~!.
The SI unit of thermal conductivity (k) is Watt per meter-Kelvin (W/(m·K)) or W·m⁻¹·K⁻¹. This unit comes from Fourier’s law of heat conduction, which states that the rate of heat flow (Q) is proportional to the area (A), the temperature gradient (dT/dx), and the thermal conductivity (k): Q = -k * A * (dT/dx). Rearranging for k, k = Q / (A * (dT/dx)). The units are W / (m² * (K/m)) = W / (m * K) = W m⁻¹ K⁻¹. Assuming the symbols in option A represent W m⁻¹ K⁻¹, it is the correct unit.
Js⁻¹ is equivalent to Watt (W), as Watt is Joules per second. Therefore, W m⁻¹ K⁻¹ is also equivalent to J s⁻¹ m⁻¹ K⁻¹. Option D is Js’m’K, which, if interpreted as J s⁻¹ m⁻¹ K, is incorrect as it lacks the K⁻¹ term. Option B, Wm/K, is W m K⁻¹, which is also incorrect. Option C is uninterpretable. Option A, Wm’K~!, is the closest representation of W m⁻¹ K⁻¹.

4. Which one of the following vitamins is synthesized in our own skin?

Which one of the following vitamins is synthesized in our own skin?

Vitamin A
Vitamin B
Vitamin C
Vitamin D
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The correct answer is D) Vitamin D.
Vitamin D (specifically Vitamin D3 or cholecalciferol) is synthesized in the skin when it is exposed to ultraviolet B (UVB) radiation from sunlight. A precursor molecule, 7-dehydrocholesterol, present in the skin, is converted into Vitamin D3 under UV light.
Vitamins A, B (group of vitamins), and C are primarily obtained from dietary sources. While the body has mechanisms to utilize and process these vitamins, they are not synthesized in the skin in the same way Vitamin D is.

5. Graphite is a much better conductor of heat and electricity than diamo

Graphite is a much better conductor of heat and electricity than diamond. This is due to the fact that each carbon atom in graphite:

undergoes sp² hybridization and forms three sigma bonds with three neighbouring carbon atoms
undergoes sp³ hybridization
is tetrahedrally bonded
is free from van der Waals force
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The correct answer is A) undergoes sp² hybridization and forms three sigma bonds with three neighbouring carbon atoms.
Graphite’s structure consists of layers of carbon atoms arranged in hexagonal lattices. Each carbon atom in graphite is sp² hybridized and forms three strong sigma bonds with three adjacent carbon atoms within the same layer. The remaining unhybridized p-orbital on each carbon atom overlaps sideways with p-orbitals of neighbouring atoms, forming a delocalized pi electron system across the layer. These delocalized electrons are free to move within the layers, making graphite a good conductor of heat and electricity.
In contrast, diamond has a tetrahedral structure where each carbon atom is sp³ hybridized and forms four strong sigma bonds with four neighbouring carbon atoms. All valence electrons are localized in these covalent bonds, so there are no free electrons to conduct electricity, making diamond an excellent electrical insulator. The strong covalent network also makes diamond an excellent thermal conductor, but the question specifically asks about electrical conductivity compared to diamond, and graphite’s delocalized electrons are key. Graphite’s thermal conductivity is also generally higher than diamond in some directions due to strong in-plane bonds and vibration modes. However, the primary reason for its *better* electrical conductivity than diamond is the presence of delocalized electrons, which stems from its sp² hybridization and bonding structure described in option A.

6. The term ‘Regur’ is used to mean:

The term ‘Regur’ is used to mean:

Laterite soil
Deltaic soil
Red soil
Black cotton soil
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The correct answer is D) Black cotton soil.
‘Regur’ is the local name for the black soils found extensively in the Deccan trap region of India. These soils are dark grey to black, rich in clay, and known for their high water retention capacity, making them suitable for cotton cultivation, hence the name ‘Black Cotton Soil’.
Laterite soils are typically red and found in areas with high rainfall and temperature. Deltaic soils are alluvial soils found in river deltas. Red soils are generally formed from the weathering of crystalline and metamorphic rocks.

7. 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
(Place)		 List II
(Normal vegetation type)
A. Western Ghats 1. Tropical Moist Deciduous
B. Himachal Pradesh 2. Tropical Evergreen
C. Haryana and Punjab 3. Himalayan Moist Forest
D. Chhotanagpur Plateau 4. Tropical Thorny Forest
2 3 4 1
1 4 3 2
2 4 3 1
1 3 4 2
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The correct answer is A) 2 3 4 1.
Matching the places with their typical vegetation:
A. Western Ghats: High rainfall zone, particularly the western slopes, supporting Tropical Evergreen forests (2).
B. Himachal Pradesh: Part of the Himalayas, vegetation varies with altitude but Moist Temperate forests are characteristic of mid-altitudes, fitting within Himalayan Moist Forest type (3).
C. Haryana and Punjab: Plains receiving less rainfall, historically having drier vegetation types including Tropical Thorny Forests before extensive agriculture (4).
D. Chhotanagpur Plateau: Receives moderate rainfall, characterized by deciduous forests that shed leaves seasonally, aligning with Tropical Moist Deciduous (1).
The correct sequence of matches is A-2, B-3, C-4, D-1. Option A provides this sequence (2 3 4 1).

8. A man is sitting in a train which is moving with a velocity of 60 km/h

A man is sitting in a train which is moving with a velocity of 60 km/hour. His speed with respect to the train is:

10/3 m/s
60 m/s
infinite
zero
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The correct answer is D) zero.
The question asks for the man’s speed *with respect to the train*. Since the man is sitting *in* the train, he is at rest relative to the train. His position relative to any point inside the train does not change.
His speed with respect to an observer outside the train would be 60 km/hour, but the reference frame specified is the train itself. Relative velocity is calculated based on the difference in velocities of the two objects. If the man’s velocity relative to the ground is V_man_ground and the train’s velocity relative to the ground is V_train_ground, the man’s velocity relative to the train is V_man_train = V_man_ground – V_train_ground. Since the man is sitting still in the train, V_man_ground = V_train_ground. Thus, V_man_train = 0.

9. Which one of the following statements is not correct?

Which one of the following statements is not correct?

The Kelvin scale of temperature is called the Absolute scale
Visible light radiation has wavelength range of 400—700 nm
The capacity to do work is called power
The wavelength of Gamma rays is less than that of X-rays
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The correct answer is C) The capacity to do work is called power.
The capacity to do work is defined as energy. Power is defined as the rate at which work is done or energy is transferred (Power = Work/Time or Energy/Time). Therefore, statement C is incorrect.
A) The Kelvin scale is indeed called the absolute scale because its zero point (0 K) is absolute zero, the theoretical point at which particles have minimal motion. B) The visible light spectrum generally ranges from approximately 400 nm (violet) to 700 nm (red). D) Gamma rays are electromagnetic waves with the shortest wavelengths and highest frequencies, making their wavelengths less than those of X-rays.

10. Which one of the following is not an example of eukaryotic organism?

Which one of the following is not an example of eukaryotic organism?

Yeast
Bacteria
Plant
Human being
This question was previously asked in
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The correct answer is B) Bacteria.
Eukaryotic organisms are characterized by having a membrane-bound nucleus and other membrane-bound organelles within their cells. Prokaryotic organisms, such as bacteria and archaea, lack a nucleus and most membrane-bound organelles. Yeast (a fungus), plants, and human beings (animals) are all examples of eukaryotic organisms.
The classification into prokaryotes and eukaryotes is one of the fundamental distinctions in biology. Eukaryotic cells are generally larger and more complex than prokaryotic cells.
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