[DAY 41] 60 DAY RAPID REVISION (RaRe) SERIES for UPSC Prelims 2023 – SCIENCE AND TECHNOLOGY, CURRENT AFFAIRS & CSAT TEST SERIES!

Solution: (c)

Explanation:

The International System of Units is a global standard for expressing the magnitudes or quantities of important natural phenomena. Also referred to as the metric system, the System of Units is commonly abbreviated as SI, which comes from the original French name, Système international d’unités.

Hence option c is correct.

Solution: (d)

Explanation:

• Scalar quantitiesare the quantities that only have a magnitude or size associated with them.
• Vector quantities are those physical quantities that have both magnitude and direction like displacement, velocity, acceleration, force, mass, etc. Hence statement 1 is incorrect.
• Scalar quantities can be expressed completely with a single number.
• Every scalar quantity is one-dimensional.
• For doing operations on scalar quantities, the usual rules of algebra work. These quantities can be added and subtracted in the same way numbers are added and subtracted. But only numbers with the same measuring unit can use the process for a scalar quantity. Hence statement 2 is incorrect.
• Some examples of scalar quantities are – the mass of an object, the distance between two points, Energy etc. Hence statement 3 is correct.

Solution: (a)

Explanation:

• Velocity is the rate at which a particular object changes its position in a certain direction.
• At its core, velocity tells the difference between an object’s final and initial positions. Velocity helps us to determine how quickly a person or an object will reach its destination from a given location. Hence statement 1 is correct.
• Speed is the amount of distance covered by an object over a specific period.
• It is helpful in estimating how fast the object is moving.
• A change in speed tells us two things: either the object’s speed has gotten very fast or slow.
• An increase in the speed of an object is called acceleration. On the other hand, if the speed decreases it is known as deceleration. If the object is not moving at all the speed is zero. Hence statement 2 is correct.
• Velocity is a vector quantity whereas speed is a scalar quantity.
• In order to find velocity, we need both magnitude and direction. Hence velocity is a vector quantity.
• Speed doesn’t take the direction of the object into consideration it is called a scalar quantity. Hence statement 3 is incorrect.

Solution: (c)

Explanation:

• Newton’s laws of motion are three basic laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows:

1. A body remains at rest, or in motion at a constant speed in a straight line, unless acted upon by a force.
2. When a body is acted upon by a force, the time rate of change of its momentum equals the force.
3. If two bodies exert forces on each other, these forces have the same magnitude but opposite directions

• A ball rolling on the ground is an example of Newton’s first law of motion. As per law, a ball rolling on the ground is prone to maintain its state of motion till infinity if no external force will be applied to it; hence the frictional force acting on the ball from the external will helps to break the motion of that ball & brings it to its rest position. Hence statement 1 is incorrect.
• Newton’s second law of motion is a quantitative illustration of the changes in the body that refers to the general situation when there is a net external force acting on the body. It relates the net external force to the acceleration of the body.
• Pushing a shopping cart is an example of Newton’s second law of motion. There is a difference between pushing an empty cart which is easy to push and pushing a loaded cart which is difficult to push. This happens because of the relationship between the mass of the object (mass of cart), the force applied to it and the acceleration produced. The mass has inversely proportional to acceleration, so that’s why the loaded cart has a slower pace than the empty cart. Hence statement 2 is correct.
• Newton’s third law of motion states that “To every action, there is always an equal and opposite reaction”.It states that when two bodies interact with each other, they have to apply forces to each other that are equal in magnitude and opposite in direction.
• Resting against a tree is an example of Newton’s third law of motion. Whenever we rest against a tree we get a reactive force from the tree to support us. In that example, the active and reactive forces are balanced in nature because both forces are applied for balancing the person. Hence statement 3 is incorrect.

Solution: (b)

Explanation:

• The force directed towards the center when an object is moving in a circular path is called centripetal force. The force is directed radially toward the center of the circle.
• When a body moves in a circular path, in the frame where the body is, the force that acts radially outward is called centrifugal force. It is also termed a pseudo or fictitious force. It comes into play only in non-inertial frames–ones in which Newton’s laws are not obeyed. Hence statement 1 is incorrect.
• The electromagnetic force between the protons in the nucleus, the electrons revolving in orbits around the nucleus, and the movement of a car on a circular track are examples of centripetal force. Hence statement 2 is correct.

Solution: (c)

Explanation:

• Kinetic energy is a form of energy possessed by an object due to its motion. It applies to all the objects which are in motion. If we want to explain kinetic energy in terms of work, then it can be stated as the work done to accelerate the object to move at a certain velocity.
• Kinetic energy is directly proportional to the body’s mass and the square of the velocity with which the body is moving. Hence statement 1 is correct.
• Kinetic energy examples include energy possessed by a moving bus, a ball thrown in the air, and a swing doing to and fro motion.
• Potential energy is defined as the stored form of energy.
• When the object starts moving, potential energy gets converted into kinetic energy. Thus, for an object to move, it must have potential energy.
• It is energy present in the object by virtue of its position with respect to other bodies.
• Energy in the electrical charges and gravitational energy are examples of potential energy.
• Potential energy depends on the mass of the object. Hence statement 2 is incorrect.
• Since Kinetic energy is a form of energy possessed by an object due to its motion, it tends to be zero when the object is in the rest position. Hence statement 3 is correct.

Solution: (c)

Explanation:

• Kepler’s First Law of Planetary Motion states that the orbit of every planet around the sun is an ellipse. The centre of the sun is found at one of the foci in the planet’s elliptical orbit. The sun is in a single point of focus, and all the planets travel in an elliptical orbit.
• This means that the distance between the sun and the planet changes as the planets move. The point at which a planet is closest to the sun is called the perihelion. The point at which the planet is found at its furthest distance from the sun is called the aphelion. Hence statement 1 is correct.
• Kepler’s Second Law of Planetary Motion states that the imaginary line that joins both the planet and sun sweeps an equal area of space in equal intervals of time. Eventually, the planets do not move at a constant speed along the orbits as believed to be. Instead, their speed varies with the equal area of space swept by the planet in a particular time limit.
• The highest speed is observed at the perihelion, while the planet moves slower at the aphelion.
• Kepler’s Third Law of Planetary Motion states that the cube of a planet’s semi-major axis is directly proportional to the square of its time period of revolution around the sun in an elliptical orbit.
• Kepler’s theories were crucial in gaining a better grasp of the dynamics of our solar system, as well as serving as a springboard for newer models that more properly approximate our planetary orbits.
• Kepler’s laws are applied in understanding and predicting the motions of natural and artificial satellites, along with those of star systems and extrasolar planets. Hence statement 2 is correct.

Solution: (b)

Explanation:

• When a body floats with its volume partially above the liquid surface, the volume of the liquid displaced by the body is equal to the volume of the submerged portion of the body. Since the body is in equilibrium, the force of buoyancy acting on the body must be equal to its weight. This is known as the law of floatation.
• The conditions for an object to float in fluid:
• The fluid should have more density than the object. Hence statement 1 is incorrect.
• The weight of the object must be equal to the upthrust force of the fluid. Hence statement 2 is correct.

Solution: (a)

Explanation:

• Wave is a form of disturbance that travels through a material medium due to the repeated periodic motion of the particles of the medium about their mean positions without any actual transportation of matter.
• Mechanical waves can be produced or propagated only in a material medium. These waves are governed by Newton’s laws of motion. Hence statement 1 is correct.
• Electromagnetic waves require no material medium for their production and propagation. i.e., they can pass through a vacuum and any other material medium. Hence statement 2 is correct.
• Visible light and ultra-violet light are examples of electromagnetic waves.
• Waves on the water’s surface, waves on strings, sound waves, etc are examples of mechanical waves. Hence statement 3 is incorrect.

Solution: (b)

Explanation:

• The distance travelled by the wave during one complete oscillation is called the wavelength of the wave.
• Wavelength is the distance between identical points (adjacent crests) in the adjacent cycles of a waveform signal propagated in space or along a wire. In wireless systems, this length is usually specified in meters (m), centimeters (cm), or millimeters (mm). In the case of infrared (IR), visible light, ultraviolet (UV), and gamma radiation (γ), the wavelength is more often specified in nanometers (nm).
• Wavelength is inversely related to frequency, which refers to the number of wave cycles per second. The higher the frequency of the signal, the shorter the wavelength. Hence statement 1 is incorrect.
• The number of oscillations made by the wave in one second is called the frequency of the wave.
• It is the number of waves that pass a fixed point in unit time; also, the number of cycles or vibrations undergone during one unit of time by a body in periodic motion. A body in periodic motion is said to have undergone one cycle or one vibration after passing through a series of events or positions and returning to its original state. Hence statement 2 is incorrect.
• The time taken by the wave to complete one oscillation is called the time period of the wave. This is the amount of time it takes for a complete wave to occur. Hence statement 3 is correct.
• The maximum displacement of the wave from its mean or equilibrium position is called the amplitude of the wave.
• It is equal to one-half the length of the vibration path. The amplitude of a pendulum is thus one-half the distance that the bob traverses in moving from one side to the other. Waves are generated by vibrating sources, their amplitude is proportional to the amplitude of the source. Hence statement 4 is correct.

Solution: (b)

Explanation:

• Heat energy can be transferred from one body to the other or from one location in a body to the other. The study of the techniques and methods adopted to transfer heat energy is known as ‘Heat Transfer’.
• Radiation is one form of heat transfer. It does not require any medium and can be used for the transfer of heat in a vacuum as well. Hence statement 1 is incorrect.
• This method uses electromagnetic waves which transfer heat from one place to the other.
• The heat and light from the sun in our solar system reach our planet using radiation only.
• Radiation is the most potent method of heat transfer. In winter when we sit near a fire we feel warm without actually touching the burning wood. This is possible by radiation only. Hence statement 2 is correct.

Solution: (c)

Explanation:

• Statement 1 is correct because conduction is indeed a process of heat transfer that occurs due to direct contact between two objects. In this process, heat flows from the object at a higher temperature to the object at a lower temperature until both objects reach the same temperature.
• Statement 2 is also correct because radiation is a process of heat transfer that occurs without any physical contact between objects. In this process, heat energy is emitted by a warm object in the form of electromagnetic waves, which travel through space and can be absorbed by other objects. This is how the sun heats the Earth, for example.
• Stefan’s Law of Radiation states that the rate at which an object emits radiation is proportional to the fourth power of its absolute temperature. It provides a quantitative relationship between the intensity of the radiation emitted by a blackbody and its temperature.

Solution: (d)

Explanation:

• The first law of thermodynamics deals with an energy conservation law, which indicates that energy can neither be created nor destroyed. However, it could be possible to change from one state to another.
• Example: Plants convert light energy into chemical energy using a process called photosynthesis. Humans consume plants, transforming chemical energy into useful work such as walking, running, doing multiple tasks, etc. Hence statement 1 is correct.
• The second law states that there will always be an increase in entropy in an isolated system. This system can evolve towards the equilibrium condition spontaneously. Therefore, there will only be an increase in the universe’s entropy, which will never reduce.
• For instance, when we take a room that has not been cleaned for months, it will only become messy and dusty every day. It will never go back to its original state (cleaned) unless someone cleans it. Once it is cleaned, the entropy of the room decreases drastically. However, the efforts to clean it have increased the entropy outside of the room. This would exceed the entropy lost. Hence statement 2 is correct.
• The Third law states that when the temperature of a system reaches absolute zero, the entropy approaches a constant value. This is what happens in the third law of thermodynamics.
• For example, the entropy is zero for a pure crystalline component whose temperature is absolute zero.
• Entropy is nothing but a quantity in thermodynamics, in which its value is fully dependent on the condition of a system. In simple words, entropy is the measure of the disorder or randomness of a system. Hence statement 3 is correct.

Solution: (d)

Explanation:

• A concave lens is defined as a lens that spreads the light beam in different directions.
• A convex lens is defined as a lens wherein the rays reflected through the surface are spread in a parallel direction.
• A concave lens is called a diverging lens whereas a convex lens is called a converging lens. Hence statement 1 is correct.
• A concave lens has one curved surface. The surface is curved inwards.
• A convex lens has two spherical surfaces, one of which is curved outwards.
• A concave lens has a virtual focus whereas a convex lens has a real focus. Hence statement 2 is correct .
• A concave mirror’s magnification is greater, equal to, or less than one.
• A convex mirror’s magnification is less than one.
• A concave lens is used in objects like flashlights, cameras, and lasers.
• A convex lens is used in objects like magnifying glasses, microscopes, etc.
• A concave lens is used for people suffering from myopia. Hence statement 3 is correct.
• A convex lens is used for people suffering from hypermetropia. Hence statement 4 is correct.

Solution: (c)

Explanation:

• Ohm’s Law states that the voltage across a conductor is directly proportional to the current flowing through it, provided all physical conditions and temperatures remain constant.
• V = IR, where V is the voltage across the conductor, I is the current flowing through the conductor and R is the resistance provided by the conductor to the flow of current. Hence statement 1 is correct.
• It only holds true if the provided temperature and the other physical factors remain constant.
• In certain components, increasing the current raises the temperature. An example of this is the filament of a light bulb, in which the temperature rises as the current is increased. In this case, Ohm’s law cannot be applied. The lightbulb filament violates Ohm’s Law. Hence statement 2 is correct.

Solution: (b)

Explanation:

• The alternating current can travel over longer distances whereas direct current cannot travel far.
• The alternating current reverses its direction while flowing in a circuit whereas direct current flows in one direction in the circuit. Hence statement 1 is correct.
• In alternating current, a rotating magnet along the wire cause of the direction of the flow of electrons.
• In direct current, steady magnetism along the wire is the cause of the direction of the flow of electrons. Hence statement 2 is incorrect.
• The frequency of the direct current is zero whereas the frequency of alternating current is 50Hz or 60Hz. Hence statement 3 is correct.
• The alternating current is of varying magnitude with time whereas the direct current is of constant magnitude. Hence statement 4 is correct.

Solution: (a)

Explanation:

• The Nobel Prizein Physics 2022 was awarded to John F. Clauser, Alain Aspect, and Anton Zeilinger.
• The Nobel Prizein Physics for 2022 was awarded for their work in quantum mechanics.
• Quantum mechanicsis a subfield of physics that describes the behavior of particles — atoms, electrons, photons, and almost everything in the molecular and sub-molecular realm. Hence statement 1 is correct.
• In 2021, the Nobel Prize in Physics was awarded to Syukuro Manabe and Klaus Hasselmann for their research on climate models and to Giorgio Parisi for his work on the interplay of disorder and fluctuations in physical systems. Hence statement 2 is incorrect.

Solution: (a)

Explanation:

• Condensation is the transformation from which water vapor converts to liquid.
• Condensation is a phenomenon in which the complete heat is removed from the substance, and from there, it converts to liquid. Hence statement 1 is correct.
• Sublimation is the transformation of a substance from a solid state to a gaseous state without getting into the liquid state. Hence statement 2 is correct.
• Dry ice and naphthalene are examples of sublimation.
• Dry ice is solid carbon dioxide. When dry ice is kept exposed to the air and the atmospheric temperature, it directly changes its solid phase to the gaseous phase, which we can see in the form of fog.
• Naphthalene is one of the organic compounds. Naphthalene is used for pesticides, and it looks like a ball. This naphthalene is seen in the washbasins in hotels, and restaurants and is of white color.  Hence statement 3 is incorrect.

Solution: (d)

Explanation:

• The speed of sound is affected by the physical properties of the medium through which it is travelling.
• Thus the speed of sound is affected by the density, temperature, humidity, and direction of the wind.
• The factors not affecting the speed of sound are pressure, amplitude, wavelength, and frequency of the sound wave. Hence option d is correct.

Solution: (c)

Explanation:

• Specific heat capacity is the amount of heat required to raise the temperature of the unit mass of a substance by 1 Kelvin. Hence statement 1 is correct.
• SI unit of specific heat capacity is Joule per kilogram per kelvin (JKg−1K−1). Hence statement 2 is correct.

Solution (a)

Explanation:

• The central government can designate a Management Authority, which grants export or import permits for the trade of specimens. Anyone who trades in a scheduled specimen must inform the appropriate authority of the transaction’s specifics. Statement 1 is correct
• The amended bill reduces the total number of schedules to four by eliminating the schedule for vermin species and reducing the number of schedules for specially protected animals to two. It also inserts a new schedule for specimens listed under CITES. Statement 2 is correct
• The bill provides for any person to voluntarily surrender any captive animals or animal products for which no compensation will be awarded and the items will become the property of the state government. Statement 3 is incorrect

Source: CLICK HERE

Solution (d)

Explanation:

• End-to-end encryption is a communication process that encrypts data being shared between two devices, preventing 3rd parties (cloud service providers, internet service providers (ISPs), and cybercriminals) from accessing data while it is being transferred. Its process uses an algorithm that transforms standard text into an unreadable format, which can only be unscrambled by those with the decryption keys. Statement 1 is correct
• The technology does not protect metadata which includes information like when a file was created, the date when a message is sent and the endpoints between which data was shared. Statement 2 is incorrect

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Solution (c)

Explanation:

The Artemis program is a robotic and human Moon exploration program led by the United States’ National Aeronautics and Space Administration (NASA) along with three partner agencies: European Space Agency (ESA), Japan Aerospace Exploration Agency (JAXA), and Canadian Space Agency (CSA). The Artemis program intends to reestablish a human presence on the Moon for the first time since the Apollo 17 mission in 1972. The major components of the program are the Space Launch System (SLS), Orion spacecraft, Lunar Gateway space station and the commercial Human Landing Systems. The program’s long-term goal is to establish a permanent base camp on the Moon and facilitate human missions to Mars.

Source: CLICK HERE

Solution (b)

Explanation:

• He became a leading figure in the freedom movement and used to write articles for the English newspaper Bande Mataram. After his acquittal in the Alipore Bomb case, Sri Aurobindo launched Karmayogin, a weekly English journal conceived as ‘A Weekly Review of National Religion, Literature, Science, Philosophy. Sri Aurobindo also launched Dharma, a weekly Bengali journal. Statement 1 is incorrect
• He was one of the founders of the youth club Anushilan Samiti which protested against the atrocities of the British government and was charged in the Alipore Bomb Case (1906-1910) and was sentenced to jail. It is colloquially referred to as the Alipore Bomb Case, the Muraripukur conspiracy, or the Manicktolla bomb conspiracy. Statement 2 is correct
• His major works include: Essays on the Gita (1922), The Life Divine (1939) Collected Poems and Plays (1942), The Synthesis of Yoga (1948), The Human Cycle (1949), The Ideal of Human Unity (1949), Savitri: A Legend and a Symbol (1950), On the Veda (1956). Statement 3 is correct

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Solution (a)

Explanation:

• The India Internet Government Forum is an initiative associated with the UN Internet Governance Forum (UN-IGF). The Internet Governance Forum (IGF) is a multi-stakeholder platform bringing representatives together from various groups, all at par to discuss public policy issues related to the Internet. India Internet Governance Forum(IIGF) has been constituted in conformance to IGF-Paragraph 72 of the Tunis Agenda of the UN-based Internet Governance forum (IGF). Statement 1 is correct
• Theme of IIGF 2022: ‘Leveraging Techade for Empowering Bharat’. India hosted it for 1st time last year (2021). Statement 2 is incorrect

Source: CLICK HERE

Solution (d)

Explanation:

The number of female members can’t be determined because the gender of A is not specified.

Hence, the option d is correct.

Solution (a)

E⁺

H^–       M⁺

B^–           C⁺

Solution (b)

Explanation: Here, if Y is the daughter of I, then Y will be the grand – daughter of G

Solution (b)

Explanation:

Father’s wife — Mother; Mother’s daughter — Sister;  Sister’s younger brother — My younger brother. So, the boy is Rakesh’s brother.

Solution (d)

Explanation:

Refer to “The data also suggests how products in these categories reach the neighbourhood kirana stores after they have established themselves in modern trade..”

Hence, option d is the correct answer.