UPSC NDA-2 Archives

11. Which one of the following is NOT an example of organic compound ?

Which one of the following is NOT an example of organic compound ?

Ammonium cyanate

Marsh gas

Urea

Cane sugar

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A) Ammonium cyanate is NOT an example of an organic compound.

– Organic compounds are generally defined as compounds containing carbon, especially those with C-H bonds. They typically originate from biological sources or contain carbon in combination with hydrogen, oxygen, nitrogen, sulfur, etc.
– There are exceptions to the “contains carbon” rule for inorganic compounds, which include oxides of carbon (CO, CO₂), carbonates, bicarbonates, cyanides, cyanates, thiocyanates, carbides, and elemental carbon forms.

– Ammonium cyanate (NH₄OCN) is an ionic salt formed from the ammonium ion (NH₄⁺) and the cyanate ion (OCN⁻). It is classified as an inorganic salt. Historically, it is famous because Friedrich Wöhler synthesized urea (an organic compound) from it in 1828, which was a significant step in disproving the vital force theory.
– Marsh gas is Methane (CH₄), a simple hydrocarbon (alkane) and a classic organic compound.
– Urea ((NH₂)₂CO) contains a carbonyl group (C=O) and amine groups (NH₂). It is an organic compound, specifically an amide.
– Cane sugar is Sucrose (C₁₂H₂₂O₁₁), a disaccharide carbohydrate, which is a large class of organic compounds.
– Therefore, Ammonium cyanate is the only compound in the list that is considered inorganic.

12. A liquid is heated up to a certain temperature. Which one of the follo

A liquid is heated up to a certain temperature. Which one of the following situation would correspond to the boiling of the liquid?

When atmospheric pressure becomes equal to the vapour pressure

When atmospheric pressure becomes less than vapour pressure

When atmospheric pressure becomes higher than the vapour pressure

When vapour pressure becomes equal to the air pressure

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A) When atmospheric pressure becomes equal to the vapour pressure corresponds to the boiling of the liquid.

– Boiling is the phase transition where a liquid turns into a gas when heated to its boiling point.
– The boiling point of a liquid is defined as the temperature at which its vapor pressure equals the surrounding environmental pressure (usually atmospheric pressure).
– At this point, the vapor pressure is sufficient to overcome the external pressure, allowing bubbles of vapor to form within the bulk of the liquid and rise to the surface.

– If atmospheric pressure is less than the vapor pressure at a given temperature, boiling occurs below the standard boiling point (e.g., at high altitudes).
– If atmospheric pressure is higher than the vapor pressure, boiling will not occur at that temperature; the liquid must be heated further to increase its vapor pressure to match the higher external pressure.
– Option D essentially states the same condition as option A, assuming “air pressure” refers to the external pressure, which is typically atmospheric pressure in an open system. Option A uses the more standard terminology.

13. Which of the following statements are correct about the electrical res

Which of the following statements are correct about the electrical resistance and resistivity of a wire?

1. Both quantities depend on the area of cross-section of the wire
2. Both depend on the temperature
3. Resistance of the wire is directly proportional to the resistivity of the wire
4. Resistivity of the wire is directly proportional to the length of the wire

Select the correct answer using the code given below :

1 and 2

1 and 3

2 and 3

2 and 4

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C) 2 and 3 are the correct statements.

– The resistance (R) of a wire is given by the formula R = ρ * (L/A), where ρ is the resistivity of the material, L is the length of the wire, and A is the area of its cross-section.
– Resistivity (ρ) is an intrinsic property of the material itself, depending on the material type and temperature, but not on the dimensions (length or area) of the specific wire.

– Statement 1: Resistance depends on the area of cross-section (inversely proportional, R ∝ 1/A), but resistivity does NOT depend on the area of cross-section. So, statement 1 is incorrect.
– Statement 2: Both resistance and resistivity of most metallic conductors are dependent on temperature. For metals, both generally increase with increasing temperature. So, statement 2 is correct.
– Statement 3: From the formula R = ρ * (L/A), Resistance (R) is directly proportional to resistivity (ρ) for a wire of fixed length and area. So, statement 3 is correct.
– Statement 4: Resistivity (ρ) is a material property and does not depend on the length of the wire. So, statement 4 is incorrect.
– Thus, only statements 2 and 3 are correct.

14. Ramesh cannot see distinctly objects kept beyond 2 m. This defect can

Ramesh cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power

+ 0.5 D

- 0.5 D

+ 0.2 D

- 0.2 D

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B) – 0.5 D is the correct power of the lens required to correct the defect.

– The person cannot see objects distinctly beyond 2 m, meaning their far point is 2 m. This is a condition of myopia (nearsightedness).
– In myopia, distant objects (effectively at infinity) are focused in front of the retina.
– A diverging lens (concave lens) is used to correct myopia, as it diverges incoming light rays slightly before they reach the eye lens, causing them to focus further back on the retina.
– Concave lenses have negative power.
– The corrective lens should form a virtual image of an object at infinity (u = ∞) at the person’s far point (v = -2 m, as the image is virtual and on the same side as the object).

– Using the lens formula, 1/f = 1/v – 1/u:
– 1/f = 1/(-2) – 1/∞
– 1/f = -1/2 – 0
– 1/f = -1/2
– The power of the lens P is given by P = 1/f (in meters).
– P = 1/(-2 m) = -0.5 Diopters (D).
– Therefore, a concave lens of power -0.5 D is needed.

15. Ms. Rani decides to convert her AC generator into a DC generator. Whic

Ms. Rani decides to convert her AC generator into a DC generator. Which one of the following she would need to use?

A split-ring type commutator

Slip rings and brushes

A stronger magnetic field

A rectangular wire loop

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A) A split-ring type commutator is the correct component needed to convert an AC generator into a DC generator.

– An AC generator produces alternating current due to the use of slip rings, which maintain continuous contact with the rotating coil.
– To convert this to direct current (DC), the direction of the current in the external circuit needs to be maintained constant.
– A split-ring commutator achieves this by reversing the connection of the coil to the external circuit every half rotation, ensuring that the current flows in the same direction in the external load.

– Slip rings are used in AC generators to connect the armature coil to the external circuit.
– A stronger magnetic field would increase the magnitude of the induced electromotive force (EMF) and current, but would not change the nature of the output from AC to DC.
– A rectangular wire loop is the armature coil, which is a component of both AC and DC generators. The type of output depends on how the coil is connected to the external circuit (via slip rings for AC, or a commutator for DC).

16. Ram records the odometer readings of his car for the distance covered

Ram records the odometer readings of his car for the distance covered from 2000 km at the start of his journey and 2400 km at the end of the journey after 8 hours. What is the average speed of the car?

50 km/h

60 km/h

70 km/h

80 km/h

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The distance covered by the car is the difference between the final and initial odometer readings:
Distance = Final reading – Initial reading
Distance = 2400 km – 2000 km = 400 km
The time taken for the journey is given as 8 hours.
Average speed is calculated as Total Distance covered divided by the Total Time taken:
Average speed = Distance / Time
Average speed = 400 km / 8 hours
Average speed = 50 km/h

Average speed is calculated by dividing the total distance covered by the total time taken.

The odometer measures the total distance traveled by a vehicle. Average speed does not reflect the instantaneous speed at any given moment during the journey, which might fluctuate due to varying road conditions or driver actions.

17. In which one of the following states ‘Roopkund’ lake is located ?

In which one of the following states ‘Roopkund’ lake is located ?

Kerala

Manipur

Himachal Pradesh

Uttarakhand

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UPSC NDA-2 – 2023

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Roopkund is a high-altitude glacial lake located in the Himalayas in the state of Uttarakhand, India. It is famous for the hundreds of ancient human skeletons found at its edge, giving it the nickname “Skeleton Lake”.

Roopkund lake, known for its mysterious skeletal remains, is situated in Uttarakhand, India.

The lake is typically frozen for most of the year and is a popular trekking destination. Scientific studies suggest the skeletons belong to people who died in a sudden, severe hailstorm around 850 AD, although recent DNA studies have revealed multiple distinct groups died at different times over several centuries.

18. In which one of the following layers of the atmosphere all weather phe

In which one of the following layers of the atmosphere all weather pheno-menon occur ?

Mesosphere

Troposphere

Thermosphere

Stratosphere

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The Troposphere is the lowest layer of Earth’s atmosphere, extending from the surface up to an average altitude of about 7-15 kilometers (varying with latitude and season). It contains about 75-80% of the atmosphere’s mass and nearly all of its water vapor and aerosols. Weather phenomena, such as clouds, precipitation, storms, fronts, and most air currents, occur almost exclusively within the troposphere due to the presence of water vapor and the process of convection.

Almost all weather phenomena on Earth occur in the Troposphere, the lowest layer of the atmosphere.

The layer above the troposphere is the Stratosphere, which contains the ozone layer and is relatively stable with minimal weather. The Mesosphere and Thermosphere are even higher layers with negligible weather activity.

19. A geographical grid has: 1. Lines that run east to west around the g

A geographical grid has:

1. Lines that run east to west around the globe to mark latitude
2. Lines that run north to south from north pole to south pole indicate longitude

Which of the statements given above is/are correct ?

1 only

2 only

Both 1 and 2

Neither 1 nor 2

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A geographical grid is formed by the intersection of lines of latitude and longitude. Lines of latitude are imaginary circles running horizontally around the globe, parallel to the Equator, measuring distance north or south of the Equator (0°). Lines of longitude are imaginary semi-circles running vertically from the North Pole to the South Pole, measuring distance east or west of the Prime Meridian (0°). Therefore, both statements are correct in describing the components of a geographical grid.

A geographical grid is defined by the network of intersecting lines of latitude (east-west) and longitude (north-south), used for pinpointing locations on Earth.

Latitude lines are called parallels, and longitude lines are called meridians. The latitude of the equator is 0°, the North Pole is 90° N, and the South Pole is 90° S. The Prime Meridian is 0°, and longitude is measured up to 180° East or West.

20. Which one of the following is the oldest era in Geological History det

Which one of the following is the oldest era in Geological History determining the age of various rock types ?

Precambrian

Mesozoic

Cenozoic

Paleozoic

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In the geological timescale, the largest division is the Eon. The history of the Earth is divided into four eons: Hadean, Archean, Proterozoic, and Phanerozoic. The first three eons together are often informally referred to as the Precambrian Supereon, preceding the Phanerozoic. The Phanerozoic Eon is divided into three eras: Paleozoic, Mesozoic, and Cenozoic. The Precambrian represents the vast majority of Earth’s history, from its formation about 4.5 billion years ago until the beginning of the Paleozoic era about 541 million years ago. Therefore, the Precambrian is the oldest era (or supereon encompassing the oldest eras) listed.

The Precambrian Supereon, comprising the Hadean, Archean, and Proterozoic Eons, represents the oldest and longest interval in Earth’s geological history, preceding the Phanerozoic Eon and its subdivisions (Paleozoic, Mesozoic, Cenozoic Eras).

The Paleozoic Era saw the “Cambrian explosion” of life, the Mesozoic is known as the age of dinosaurs, and the Cenozoic is the current era, known as the age of mammals. These are all significantly younger than the Precambrian.