UPSC NDA-2 Archives

41. Which one of the following is a non-metallic mineral ?

Which one of the following is a non-metallic mineral ?

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Iron

Mica

Copper

Bauxite

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Minerals are broadly classified into metallic and non-metallic minerals. Metallic minerals contain one or more metallic elements, while non-metallic minerals do not. Iron, Copper, and Bauxite (an ore of aluminum) are metallic minerals. Mica is a silicate mineral that does not contain metallic elements and is classified as a non-metallic mineral.

Metallic minerals are sources of metals (e.g., iron ore, copper ore, bauxite), while non-metallic minerals are used for various purposes other than obtaining metals (e.g., building materials, chemicals, fertilizers, gemstones).

Examples of metallic minerals include hematite, magnetite, bauxite, chalcopyrite, chromite, gold, silver, etc. Examples of non-metallic minerals include mica, limestone, gypsum, dolomite, feldspar, quartz, diamond, coal, petroleum, etc.

42. Which of the following are the characteristics of electromagnetic wave

Which of the following are the characteristics of electromagnetic waves ?

They are elastic waves.
They can also move in vacuum.
They have electric and magnetic components which are mutually perpendicular.
They move with a speed equal to 3 lakh meters per second.

Select the correct answer using the code given below :

1, 2, 3 and 4

1, 2 and 4 only

2 and 3 only

3 and 4 only

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Statement 1 is incorrect because electromagnetic waves are not elastic waves; they do not require a medium for propagation. Statement 4 is incorrect as electromagnetic waves move with a speed of approximately 3 x 10^8 meters per second (speed of light), which is 3 lakh *kilometres* per second, not 3 lakh meters per second. Statements 2 and 3 correctly describe characteristics of electromagnetic waves: they can travel through a vacuum, and their electric and magnetic field components are mutually perpendicular.

Electromagnetic waves are transverse waves consisting of oscillating electric and magnetic fields that propagate through space at the speed of light, even in a vacuum. They do not require a material medium, unlike mechanical waves (like sound or elastic waves). The electric and magnetic fields are perpendicular to each other and to the direction of wave propagation.

The speed of electromagnetic waves in a vacuum is a fundamental constant, denoted by ‘c’, approximately 299,792,458 meters per second, often rounded to 3 x 10^8 m/s or 300,000 km/s (3 lakh km/s). The spectrum of electromagnetic waves includes radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays, all differing in wavelength and frequency but sharing these fundamental characteristics.

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43. Radiations coming from the Sun are mostly in the form of

Radiations coming from the Sun are mostly in the form of

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light only.

light and long wavelength infrared.

light and short wavelength infrared.

both short and long wavelength infrared.

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The correct option is C) light and short wavelength infrared.

The Sun emits electromagnetic radiation across a broad spectrum, with the peak intensity in the visible light region, and significant contributions in the infrared and ultraviolet regions.

The Sun’s surface temperature (around 5500°C or 5778 K) causes it to radiate energy according to Wien’s displacement law and Planck’s law. The peak wavelength falls in the visible spectrum (around 500 nm). The emitted radiation also includes infrared. Due to the high temperature, the infrared radiation from the Sun is predominantly in the short-wavelength range (near-infrared, roughly 0.7 to 5 µm), which is higher energy compared to the long-wavelength infrared emitted by cooler objects like the Earth’s surface (which peaks around 10 µm). Therefore, solar radiation consists mainly of visible light and short wavelength infrared.

44. The temperature of a place on one sunny day is 113 in Fahrenheit scale

The temperature of a place on one sunny day is 113 in Fahrenheit scale. The Kelvin scale reading of this temperature will be

318 K

45 K

62.8 K

335.8 K

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The correct option is A) 318 K.

To convert temperature from Fahrenheit to Kelvin, one must first convert from Fahrenheit to Celsius and then from Celsius to Kelvin.

The formula for converting Fahrenheit (T_F) to Celsius (T_C) is T_C = (T_F – 32) * 5/9.
Given T_F = 113 °F, T_C = (113 – 32) * 5/9 = 81 * 5/9 = 9 * 5 = 45 °C.
The formula for converting Celsius (T_C) to Kelvin (T_K) is T_K = T_C + 273.15. For practical purposes in MCQs, 273 is often used.
Using 273: T_K = 45 + 273 = 318 K.
Using 273.15: T_K = 45 + 273.15 = 318.15 K.
Since 318 K is an option and close to 318.15 K, it is the intended answer using the approximation of 273.

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45. A rigid body of mass 2 kg is dropped from a stationary balloon kept at

A rigid body of mass 2 kg is dropped from a stationary balloon kept at a height of 50 m from the ground. The speed of the body when it just touches the ground and the total energy when it is dropped from the balloon are respectively (acceleration due to gravity = 9.8 m/s²)

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980 m.s⁻¹ and 980 J

√980 m.s⁻¹ and √980 J

980 m.s⁻¹ and √980 J

√980 m.s⁻¹ and 980 J

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The correct option is D) √980 m.s⁻¹ and 980 J.

The problem involves calculating the final speed of a falling object using kinematics and determining the total mechanical energy at the beginning of the fall using the principle of conservation of energy.

Given: mass (m) = 2 kg, initial height (h) = 50 m, initial velocity (u) = 0 m/s, acceleration due to gravity (g) = 9.8 m/s².
1. Speed when it just touches the ground (v): Using the kinematic equation v² = u² + 2gh, we get v² = 0² + 2 * 9.8 * 50 = 980. So, v = √980 m/s.
2. Total energy when dropped: At the moment of dropping from a height h with zero initial velocity, the total mechanical energy is the sum of potential energy and kinetic energy. Potential Energy (PE) = mgh = 2 kg * 9.8 m/s² * 50 m = 980 J. Kinetic Energy (KE) = ½mu² = ½ * 2 kg * (0 m/s)² = 0 J. Total Energy = PE + KE = 980 J + 0 J = 980 J. (Note: By conservation of energy, the total energy remains 980 J just before hitting the ground, where all potential energy is converted to kinetic energy).

46. Compared to audible sound waves, ultrasound waves have

Compared to audible sound waves, ultrasound waves have

higher speed.

higher frequency.

longer wavelength.

both higher speed and frequency.

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The correct option is B) higher frequency.

Ultrasound waves are defined as sound waves with frequencies higher than the upper limit of human hearing, which is typically considered to be 20 kilohertz (kHz). Audible sound waves have frequencies between approximately 20 Hz and 20 kHz.

The speed of sound in a given medium is generally constant for all frequencies. The relationship between speed (v), frequency (f), and wavelength (λ) is v = fλ. Since ultrasound has a higher frequency (f) than audible sound in the same medium with constant speed (v), its wavelength (λ) must be shorter. Therefore, compared to audible sound waves, ultrasound waves have higher frequency and shorter wavelength, but the speed remains the same in the same medium.

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47. Which one of the following diseases may be caused by the deficiency of

Which one of the following diseases may be caused by the deficiency of vitamin C ?

Rickets

Rabies

Hepatitis

Scurvy

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The correct option is D) Scurvy.

Scurvy is a disease resulting from a deficiency of vitamin C (ascorbic acid).

Vitamin C is essential for the synthesis of collagen, a protein required for healthy skin, gums, blood vessels, bones, and connective tissue. Symptoms of scurvy include fatigue, gum disease, joint pain, poor wound healing, and bleeding. Rickets is caused by Vitamin D deficiency. Rabies is a viral infection. Hepatitis is typically a viral infection causing liver inflammation.

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48. Which one of the following statements regarding viruses is not true

Which one of the following statements regarding viruses is not true ?

Viruses need living cells to reproduce.

All viruses are parasites.

Viruses can synthesize their food through photosynthesis.

Viruses are similar to chemical substances outside the host.

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The correct option is C) Viruses can synthesize their food through photosynthesis.

Viruses are acellular entities that lack the metabolic machinery necessary for processes like photosynthesis or self-synthesis of food. They are obligate intracellular parasites.

Viruses require a host cell to reproduce because they lack the necessary enzymes and ribosomes. They hijack the host cell’s machinery to replicate. Outside a host cell, a virus particle is essentially an inert complex of genetic material and protein, behaving like a chemical substance. They obtain energy and building blocks from the host cell, not through photosynthesis or any independent metabolic activity.

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49. Which one of the following is a bacterium that causes disease in the h

Which one of the following is a bacterium that causes disease in the human body ?

Varicella zoster

Trypanosoma gambiense

Salmonella typhi

Plasmodium falciparum

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The correct option is C) Salmonella typhi.

The question asks to identify a bacterium from the given options that causes disease in humans.

Salmonella typhi is a rod-shaped, Gram-negative bacterium that causes typhoid fever in humans. Varicella zoster is a virus (causes chickenpox and shingles). Trypanosoma gambiense is a protozoan (causes African sleeping sickness). Plasmodium falciparum is a protozoan (causes malaria).

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50. Thyroid gland produces a hormone called “Thyroxine” which

Thyroid gland produces a hormone called “Thyroxine” which

controls blood glucose levels.

controls ovulation.

controls metabolic rate.

maintains pregnancy.

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The correct option is C) controls metabolic rate.

Thyroxine, produced by the thyroid gland, is the main hormone responsible for regulating the body’s metabolism, including how fast the body uses energy and makes proteins.

Thyroxine (T4) and triiodothyronine (T3), the active form, affect almost every cell in the body. They increase the basal metabolic rate, influence protein synthesis, help regulate long bone growth, and play a role in neural maturation. Blood glucose levels are primarily controlled by insulin and glucagon, ovulation by FSH, LH, and estrogen, and maintenance of pregnancy mainly by progesterone.

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