UPSC NDA-2

41. Which one of the following was composed by Harishena?

Which one of the following was composed by Harishena?

Subscribe on YouTube
Nashik Inscription of Gautami Balashri
Prayaga Prashasti of Samudragupta
Deopara Prashasti of Vijayasena
Hathigumpha Inscription of Kharavela
This question was previously asked in
UPSC NDA-2 – 2022
Download PDFAttempt Online
The Prayaga Prashasti of Samudragupta was composed by Harishena.
Harishena was a 4th-century poet and minister in the court of the Gupta emperor Samudragupta. He composed the Prayaga Prashasti, an inscription carved on the Ashoka pillar in Allahabad (Prayagraj). This inscription is a eulogy praising Samudragupta’s military campaigns, conquests, and personal qualities, providing valuable historical information about his reign.
The Nashik Inscription of Gautami Balashri relates to the Satavahana dynasty ruler Gautamiputra Satakarni. The Deopara Prashasti was composed by Umapatidhar in praise of the Sena king Vijayasena. The Hathigumpha Inscription was issued by King Kharavela of Kalinga.

Join Our Telegram Channel

42. A negative work is done when an applied force F and the corresponding

A negative work is done when an applied force F and the corresponding displacement S are

Join Our Telegram Channel
perpendicular to each other.
parallel to each other.
anti-parallel to each other.
equal in magnitude.
This question was previously asked in
UPSC NDA-2 – 2021
Download PDFAttempt Online
A negative work is done when an applied force F and the corresponding displacement S are anti-parallel to each other.
The work done (W) by a constant force (F) when an object undergoes a displacement (S) is given by the dot product of the force and displacement vectors: $W = \vec{F} \cdot \vec{S} = |\vec{F}| |\vec{S}| \cos\theta$, where $\theta$ is the angle between the force and displacement vectors. Work done is positive when the force and displacement are in the same general direction ($0^\circ \le \theta < 90^\circ$), zero when they are perpendicular ($\theta = 90^\circ$), and negative when they are in opposite directions ($90^\circ < \theta \le 180^\circ$). When the force and displacement are anti-parallel ($\theta = 180^\circ$), $\cos\theta = -1$, and the work done is maximum negative: $W = -FS$.
Examples of negative work include the work done by friction when an object moves (friction acts opposite to motion), or the work done by gravity when an object is lifted upwards (gravity acts downwards while displacement is upwards).

Subscribe on YouTube

43. Which one of the following is not a conservative force ?

Which one of the following is not a conservative force ?

Join Our Telegram Channel
Frictional force
Electric force
Gravitational force
Spring force
This question was previously asked in
UPSC NDA-2 – 2021
Download PDFAttempt Online
Frictional force is not a conservative force.
A conservative force is one for which the work done in moving an object between two points is independent of the path taken, or equivalently, the work done in moving an object around a closed loop is zero. Gravitational force, electric force, and spring force are examples of conservative forces because the work done by them depends only on the initial and final positions. Frictional force, however, is a dissipative force and the work done by friction depends on the path length; the longer the path, the more work is done against friction. Work done by friction over a closed loop is generally non-zero and negative (energy is dissipated as heat).
Forces like friction and air resistance are examples of non-conservative forces. The work done by non-conservative forces leads to a change in the mechanical energy of the system, often converting mechanical energy into other forms like heat or sound.

Subscribe on YouTube

44. The image of an object formed by a plane mirror is

The image of an object formed by a plane mirror is

Join Our Telegram Channel
erect, real and larger.
erect, virtual and same size.
inverted, virtual and same size.
inverted, real and smaller.
This question was previously asked in
UPSC NDA-2 – 2021
Download PDFAttempt Online
The image of an object formed by a plane mirror is erect, virtual and the same size as the object.
A plane mirror forms an image that is always virtual (cannot be projected onto a screen), erect (same orientation as the object), laterally inverted (left appears right and vice versa), and of the same size as the object. The image is also located as far behind the mirror as the object is in front.
Real images are formed when light rays converge at a point after reflection or refraction, whereas virtual images are formed when light rays appear to diverge from a point. Plane mirrors produce virtual images because the reflected rays do not actually meet but only appear to meet behind the mirror.

Subscribe on YouTube

45. When a light beam falls on a triangular glass prism, a band of colours

When a light beam falls on a triangular glass prism, a band of colours is obtained. Which one of the following statements is correct in this regard?

Join Our Telegram Channel
Red light bends the most, as the refractive index of glass for red light is greatest.
Red light bends the most, as the refractive index of glass for red light is lowest.
Violet light bends the most, as the refractive index of glass for violet light is greatest.
Violet light bends the most, as the refractive index of glass for violet light is lowest.
This question was previously asked in
UPSC NDA-2 – 2021
Download PDFAttempt Online
The correct answer is that Violet light bends the most because the refractive index of glass for violet light is greatest.
When white light passes through a prism, it splits into its constituent colours due to dispersion. The amount of bending (deviation) of light by a prism depends on the refractive index of the prism material for that specific colour. According to Cauchy’s formula and experimental observations, the refractive index of a material decreases as the wavelength of light increases. Violet light has the shortest wavelength among the visible colours, while red light has the longest wavelength. Therefore, the refractive index of glass is highest for violet light and lowest for red light. A higher refractive index leads to a greater deviation (bending).
The deviation of light by a prism is given approximately by $\delta = (\mu – 1)A$, where $\mu$ is the refractive index of the prism material and A is the angle of the prism. Since $\mu_{\text{violet}} > \mu_{\text{red}}$, it follows that $\delta_{\text{violet}} > \delta_{\text{red}}$. This causes violet light to be deviated the most and red light the least, resulting in the separation of colours observed as a spectrum.

Subscribe on YouTube

46. Which one of the following figures correctly shows the path of a ray o

Which one of the following figures correctly shows the path of a ray of light through a glass prism ?

Join Our Telegram Channel
Image of path of light through prism
Image of path of light through prism
Image of path of light through prism
Image of path of light through prism
This question was previously asked in
UPSC NDA-2 – 2021
Download PDFAttempt Online
Assuming Option A depicts the standard correct path of a ray of light through a glass prism. A ray of light entering a prism from air bends towards the normal upon entering the glass (denser medium). Inside the prism, it travels in a straight line. Upon exiting the prism from glass back into air (rarer medium), it bends away from the normal.
According to Snell’s Law, when light travels from a rarer medium (like air) to a denser medium (like glass), the ray bends towards the normal. When it travels from a denser medium to a rarer medium, it bends away from the normal. For a prism, the incident ray bends towards the normal at the first surface and the emergent ray bends away from the normal at the second surface. The net deviation of the ray is always towards the base of the prism for a ray entering one face and exiting another.
Different paths might be depicted in the options, such as bending away from the normal upon entry, no bending, total internal reflection, or bending towards the apex. Only one diagram correctly shows the path based on the principles of refraction. Without seeing the specific diagrams, it is assumed option A represents the correct standard path with deviation towards the base.

Subscribe on YouTube

47. The unit of the ratio between thrust and impulse is same as that of

The unit of the ratio between thrust and impulse is same as that of

Join Our Telegram Channel
frequency
speed
wavelength
acceleration
This question was previously asked in
UPSC NDA-2 – 2021
Download PDFAttempt Online
The correct option is A. We need to find the unit of the ratio between thrust and impulse and compare it with the units of the given options.
Thrust is a force. The SI unit of force is Newton (N), which is equivalent to $\text{kg} \cdot \text{m/s}^2$.
Impulse is the change in momentum, or force multiplied by time. The SI unit of impulse is N·s, which is equivalent to $(\text{kg} \cdot \text{m/s}^2) \cdot \text{s} = \text{kg} \cdot \text{m/s}$.
The ratio $\frac{\text{Thrust}}{\text{Impulse}}$ has units $\frac{\text{N}}{\text{N} \cdot \text{s}} = \frac{1}{\text{s}}$.
The unit $1/\text{s}$ is the unit of frequency. Frequency is the number of cycles or events per unit time, measured in Hertz (Hz), where 1 Hz = $1/\text{s}$.
Let’s check the units of the options:
A) Frequency: $1/\text{s}$ or Hz.
B) Speed: m/s.
C) Wavelength: m.
D) Acceleration: m/s².
The unit of the ratio is the same as the unit of frequency.
Impulse is also equal to the change in momentum ($\Delta p = m \Delta v$). So the unit of impulse is also $(\text{kg}) \cdot (\text{m/s}) = \text{kg} \cdot \text{m/s}$. Using this, the ratio unit is $\frac{\text{kg} \cdot \text{m/s}^2}{\text{kg} \cdot \text{m/s}} = \frac{1}{\text{s}}$.

Subscribe on YouTube

48. Which one of the following is the chemical formula of Plaster of Paris

Which one of the following is the chemical formula of Plaster of Paris ?

Join Our Telegram Channel
$ ext{CaSO}_4 cdot rac{1}{2} ext{ H}_2 ext{O}$
$ ext{CaSO}_4 cdot 2 ext{ H}_2 ext{O}$
$ ext{CaSO}_4 cdot 5 ext{ H}_2 ext{O}$
$ ext{CaSO}_4 cdot 4 ext{ H}_2 ext{O}$
This question was previously asked in
UPSC NDA-2 – 2021
Download PDFAttempt Online
The correct option is A. The chemical formula of Plaster of Paris is Calcium Sulfate hemihydrate, which is $\text{CaSO}_4 \cdot \frac{1}{2} \text{ H}_2\text{O}$.
Plaster of Paris is produced by heating Gypsum ($\text{CaSO}_4 \cdot 2 \text{ H}_2\text{O}$) to about 150°C (302°F). This heating process removes three-quarters of the water of crystallization, leaving the hemihydrate form. When mixed with water, Plaster of Paris rehydrates and sets into a hard mass, which is chemically Gypsum.
Gypsum ($\text{CaSO}_4 \cdot 2 \text{ H}_2\text{O}$) is Calcium Sulfate dihydrate. It is a naturally occurring mineral. The setting of Plaster of Paris is an exothermic reaction: $\text{CaSO}_4 \cdot \frac{1}{2} \text{ H}_2\text{O} + 1\frac{1}{2} \text{ H}_2\text{O} \rightarrow \text{CaSO}_4 \cdot 2 \text{ H}_2\text{O}$.

Subscribe on YouTube

49. What is the total number of covalent bonds in methanol ?

What is the total number of covalent bonds in methanol ?

Subscribe on YouTube
3
4
5
6
This question was previously asked in
UPSC NDA-2 – 2021
Download PDFAttempt Online
The correct option is C. Methanol has the chemical formula $\text{CH}_3\text{OH}$. To find the number of covalent bonds, we need to consider its molecular structure.
The structure of methanol involves a central carbon atom bonded to three hydrogen atoms, one oxygen atom, and the oxygen atom is bonded to one hydrogen atom.
Drawing the Lewis structure or structural formula:
Carbon (C) forms single bonds with 3 Hydrogen atoms (H) and 1 Oxygen atom (O).
Oxygen (O) forms a single bond with the Carbon atom (C) and a single bond with 1 Hydrogen atom (H).
The bonds are: 3 C-H single bonds, 1 C-O single bond, and 1 O-H single bond.
Total number of covalent bonds = 3 (C-H) + 1 (C-O) + 1 (O-H) = 5.
Each line in the structural formula represents a single covalent bond, which is a pair of shared electrons. Carbon typically forms 4 bonds, Oxygen typically forms 2 bonds and has 2 lone pairs, and Hydrogen forms 1 bond. This structure satisfies the valency rules for all atoms.

Join Our Telegram Channel

50. Which one of the following ions is not iso-electronic with F⁻ ?

Which one of the following ions is not iso-electronic with F⁻ ?

Join Our Telegram Channel
O²⁻
Na⁺
Ne
N⁻
This question was previously asked in
UPSC NDA-2 – 2021
Download PDFAttempt Online
The correct option is D. Iso-electronic species are atoms or ions that have the same number of electrons. We need to find which species among the options does not have the same number of electrons as F⁻.
A neutral Fluorine atom (F) has 9 electrons (atomic number = 9). The F⁻ ion has gained one electron, so it has $9 + 1 = 10$ electrons.
Let’s find the number of electrons for each option:
A) O²⁻: Neutral Oxygen (O) has 8 electrons (atomic number = 8). O²⁻ has gained two electrons, so $8 + 2 = 10$ electrons.
B) Na⁺: Neutral Sodium (Na) has 11 electrons (atomic number = 11). Na⁺ has lost one electron, so $11 – 1 = 10$ electrons.
C) Ne: Neutral Neon (Ne) has 10 electrons (atomic number = 10).
D) N⁻: Neutral Nitrogen (N) has 7 electrons (atomic number = 7). N⁻ has gained one electron, so $7 + 1 = 8$ electrons.
Thus, N⁻ has 8 electrons, while F⁻ has 10 electrons. N⁻ is not isoelectronic with F⁻.
Isoelectronic species often have similar chemical and physical properties due to having the same electron configuration. The species O²⁻, F⁻, Ne, Na⁺, Mg²⁺, Al³⁺ are all isoelectronic with 10 electrons, having the electron configuration of Neon.

Subscribe on YouTube
Page 1Page 2Page 3Page 4Page 5
Test 1Test 2Test 3Test 4Test 5Test 6Test 7Test 8Test 9Test 10Test 11Test 12Test 13Test 14Test 15Test 16Test 17Test 18Test 19Test 20