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Physics — UPSC Prelims Science & Environment previous year questions — page 5

177 solved previous year questions on Physics, papers from 1990 to 2023, drawn from UPSC CSE Prelims, UPPCS, UPSC CDS. Each carries the printed answer key and the explanation from the source compilation.

1. #161Practice set
   With reference to the National Agroforestry Policy, consider the following statements: 1. The policy aims to integrate trees, crops and livestock on the same plot of land to improve productivity of land. 2. The policy aims to achieve a target of tree cover in the country. 3. India was the first country in the world to adopt a National level Agroforestry policy.How many of the statements given above are correct?
   • AOnly one
   • BOnly two
   • CAll three
   • DNone
   Answer: (B) Only two
   Explanation

   Option b is the correct National Agroforestry policy was approved by government in February 2014 and was launched of the same year. It recognizes the important role can play in promoting sustainable land degradation, and improving rural policy aims to increase the area under agroforestry current 10 million hectares to 25 million hectares Statement 1 is correct: The National Agroforestry with the practice of integrating trees, crops, on the same plot ofland to increase the the land. It also recognizes that agroforestry can the development of sustainable value chains for such as timber and non-timber forest 2 is incorrect: Though the policy aims to country's forest cover, it does not aim to achieve a tree cover in the country. This is the target set by Forest Policy of 1988, which is a separate 3 is correct: India was the first country in to adopt a National Agroforestry Policy in May 2014

2. #162Practice set
   Consider the following statements regarding the Green Term Ahead Market (GTAM) in electricity sector: 1. It will create a Pan India Market for selling and buying of renewable energy. l.lfl, 2. GTAM contracts will be segregated into Solar and Non-Solar Renewable Purchase Obligations.Which of the statements given above is/are correct?
   • A1 only
   • B2 only
   • CBoth 1 and 2
   • DNeither 1 nor 2
   Answer: (C) Both 1 and 2
   Explanation

   Option c is the correct 1 is correct. Union Power Ministry has Ahead Market ( GTAM) in electricity. The first product for renewable energy sector world. GTAM would benefit buyers of renewable competitive prices and transparent and It will also benefit sellers as they will to Pan India 2 is correct. Transactions through be in nature with clear identification buyers and sellers, there will not be in accounting for Renewable Purchase GTAM contracts will be segregated into Solar Non-Solar RPO as RPO targets are also Solution: Option c is the correct 1 is correctly matched. Environment has been released biennially by Yale and in collaboration with the World Environmental Performance Index (EPI) provides summary of the state of sustainability world. l,Jsing 32 performance indicators across 11 the EPI ranks 180 countries on and ecosystem 2 is correctly matched; Global Climate Risk Index by the

3. #163Practice set
   With respect to International Solar Alliance, which of the following statements is incorrect?
   • AIt was launched at COP-21 of United Nations Framework Convention on Climate Change
   • BMembership is limited only to countries lying fully or partially in between Tropic of Cancer and Tropic of Capricorn
   • CHeadquarter of the alliance is in Gurugram
   • DAlliance aims for installed solar capacity globally by 2030
   Answer: (B) Membership is limited only to countries lying fully or partially in between Tropic of Cancer and Tropic of Capricorn
   Explanation

   Option b is the correct a is correct: ISA was launched at 21 at Paris in 2015. The purpose of the Alliance is to bring countries on a platform clean energy, sustainable environment, transport and clean b is incorrect: the to only those countries which lied partially in the tropics. But recently India has expanded it to of United Nation even beyond the c is correct: Headquarter of ISA is set up at of Solar Energy, d is correct: ISA has set a target of 1000 GW solar capacity globally by 2030. For which it the need of 1 trillion dollars

4. #164Full-length test
   With reference to 'Gamma Ray Bursts (GRB consider the following statements: 1. These are high-energy short gamma radiation originating from distant parts of the universe. 2. They are emitted equally in every direction from their source. 3. At present, only two observed GRBs have originated from within the Milky Way galaxy. 4. GRBs events can produce ripples in the fabric of space-time called gravitational waves.How many of the above given statements are correct?
   • AOnly one
   • BOnly two
   • COnly three
   • DAll the four
   Answer: (B) Only two
   Explanation

   Option b is the correct 1 is correct: GRBs (Gamma Ray Bursts) are high energy short gamma radiations that originate from of the universe. They are the most energetic events known in the universe and can last to several 2 is incorrect: GRBs are not emitted equally direction. They have a beamed emission means they are more intense in certain directions intense in 3 is incorrect: At present, no observed originated from within the Milky Way galaxy. GRBs have been observed in faraway 4 is correct: GRBs events can produce the fabric of space-time called gravitational bursts (GRBs) events are incredibly release huge amounts of energy in the form of matter

5. #165Full-length test
   Which of the following are the possible impacts of geo-magnetic storms? 1. Cause beautiful auroras in the sky. 2. Disrupt satellite communications and GPS systems. 3. Cause power outages in a country. 4. Can increase the risk of cancer for people. 5. Cause disruption to airline and air traffic control systems. 6. Cause disturbances in oceanic gyre circulation.Select the correct answer using the codes given below
   • A1, 2, 3, 4 and 5 only
   • B1, 2, 4 and 6 only
   • C1, 2, 3 and 5 only
   • D2, 4, 5 and 6 only
   Answer: (A) 1, 2, 3, 4 and 5 only
   Explanation

   Option a is the correct storms are a type of space weather can affect the Earth's magnetic field. They are caused wind disturbances, which can disrupt the normal charged particles around the 1 is correct: One of the most visible pleasing impacts of geomagnetic storms display of auroras in the polar regions. Auroras charged particles from the solar wind interact with magnetic field and are channeled towards the 2 is correct: Geomagnetic storms can satellite communications and navigation systems radio signals and GPS 3 is correct: During a severe geomagnetic currents induced by the storm can flow lines and transformers, causing power outages to 4 is correct: Exposure to radiation from a can pose a risk to astronauts and airline crews at Solar storms emit radiation, exposure to which to humans and can cause organ damage, and 5 is correct: Geomagnetic storms can interfere and communication s

6. #166Full-length test
   Consider the following statements about the greenhouse effect: 1. Green-house effect is responsible for life on the earth. 2. It is a naturally occurring phenomenon that shields the earth from harmful solar radiation. 3. Green-house effect is higher at higher elevations.How many of the above given statements are correct?
   • AOnly one
   • BOnly two
   • CAll three
   • DNone
   Answer: (A) Only one
   Explanation

   Option a is the correct 1 is correct. The green-house effect is a phenomenon that acts as a blanket and keeps warm. It maintains the temperature suitable for to survive. The average temperature of earth's be instead of present and earth would and lifeless 2 is incorrect. It has no role in protection solar radiation. Due to trapping of terrestrial radiations by greenhouse gases there of lower 3 is incorrect. Due to lesser density and air column at higher elevation as compared to the air temperature is generally cooler. As a the rarified atmosphere there is lesser greenhouse gases to support this effect. Due to effect is weaker at higher elevations

7. #167Full-length test
   With reference to the Raman Spectroscopy, consider the following: 1. It works on the principle of scattering of light waves when it interacts with an object. 2. It is used to characterize the chemical composition and structure of only liquid samples. 3. It can be used to detect RNA virus traces present in saliva samples. 4. It can be used to provide molecular fingerprint of physiological biomarkers.How many of the above given statements are correct?
   • AOnly one
   • BOnly two
   • COnly three
   • DAll four oru.nilll
   Answer: (C) Only three
   Explanation

   Option c is the correct I is correct. Raman spectroscopy is an where scattered light is used to measure energy modes of a sample. In 1928, Raman 11 { that when a stream of light passes through a fraction of the light scattered by the liquid is of colour. The Raman Effect is when the change energy of the light is affected by the vibrations of or material under observation, leading to a its wavelength. Raman spectra result from scattering by vibrating molecules whereas IR spectra result absorption by vibrating 2 is incorrect. It can be used to the chemical composition and structure of whether solid, liquid, gas, gel, slurry or 3 is correct. It can be used to detect RNA present in saliva samples. In case of COVID it can be used only for screening. Because virus detected could be a common cold virus as well other RNA virus such as 4 is correct. Raman spectroscopy has shown to have massive po

8. #168Full-length test
   Which of the following options best describes the term "e-fuels"?
   • ABattery induced energy used in electric vehicles
   • BHydrogen fuel produced using electricity
   • CThe energy consumed by computers in the process of Bitcoin mining
   • DCrude oil refined using the zero human contact technology
   Answer: (B) Hydrogen fuel produced using electricity
   Explanation

   Option b is the correct production involves the process of breaking a into hydrogen (H2) and oxygen electrolysis process and combining hydrogen with from the atmosphere. As this process use of electricity to make carbon hydrogen these fuels are called e-fuels. Important Tips Advantages of e-fuels are climate-neutral; no additional greenhouse gases are produced while they are in use. can be easily stored and transported over long distances without any energy loss. emit significantly less nitrogen oxide and particulate matter than conventional fuels. do not cause any disposal or recycling issues. can be used in today's engines and heating systems

9. #169Full-length test
   Which among the following correctly describes the term Ecological efficiency?
   • AChemical energy converted into biomass from one trophic level to another
   • BAbility of plants to convert solar energy into chemical energy
   • CAmount of inorganic matter stored by producers
   • DOxygen availability at the lowest trophic level
   Answer: (A) Chemical energy converted into biomass from one trophic level to another
   Explanation

   Option a is the correct percentage of usable chemical energy biomass from one trophic level to the next is efficiency. Ecological efficiency depends on the proportion of assimilated energy incorporated in growth, storage and reproduction. Put simply, it depends on the total amount of energy an organism needs to survive and thrive. Depending on what types of species an ecosystem is involved, the Ecological efficiency ranges from with a loss of of the original energy. This energy is generally lost as heat to Since each trophic level only receives an average of energy from previous trophic levels, there won't be more than 4-5 trophic structures

10. #170Full-length test
    Which of the following statements best reflects the meaning of Tidal Disruption Events?
    • AA destruction of stars by the gravitational force of the super massive black holes in space
    • BA destruction of stars caused when the stars run out of their fuel. { }
    • CA disruption caused. due to the collision of stars of equal mass and density
    • DA disruption in the direction of light caused by the gravitational force of stars in Space
    Answer: (A) A destruction of stars by the gravitational force of the super massive black holes in space
    Explanation

    Option a is the correct a is correct: A Tidal Disruption Event (TDE) astronomical phenomenon that occurs when a near the Super Massive Black Holes, it gets the gravitational force of black holes resulting in flare of electromagnetic radiation and these tidal disruption events. A tidal force is the the strength of gravity between two points. If the exerted on a body is greater than the that keeps it together, the body will get b is incorrect: Tidal Disruption Events are to the disruption of stars due to the loss of stars take millions of years to die and when a star all its hydrogen fuel, it expands to become a red eventually stars burst out, resulting in the formation dwarfs and black c is incorrect: Tidal Disruption Events (TDEs) related to the disruption event caused by the collision stars with equal masses and density. { d is incorrect: TDEs are not related to of light by the gravitat

11. #171Full-length test
    Gravitational lensing occurs when the gravitational field from a massive object warps space and deflects light from a distant object. The bull's-eye patterns are so-called "Einstein rings" which are the most elegant manifestation of the gravitational lensing phenomenon. In this reference, which of the following statement appropriately describes the method of formation of Einstein's rings?
    • AThey are produced when two galaxies are almost aligned one behind the other
    • BThey are produced when two galaxies are almost perpendicular to each other
    • CThey are produced when two black holes are almost aligned one behind the other
    • DThey are produced when two black holes are almost perpendicular to each other
    Answer: (A) They are produced when two galaxies are almost aligned one behind the other
    Explanation

    Option a is the correct bull's-eye patterns are created (as shown in figure) as from galaxies twice as far away is distorted into by the gravity of the giant elliptical galaxies. is called gravitational lensing, first Albert Einstein almost a century ago. occurs when the gravitational field from a warps space and deflects light from a distant bull's-eye patterns are so-called "Einstein are the most elegant manifestation of the Einstein rings are produced when are almost perfectly aligned, one behind Hence, option a is correct

12. #172Full-length test
    With reference to the UN Peacekeeping, consider the following statements: 1. UN General Assembly has power to authorise a peacekeeping operation in regions of conflict by adopting a resolution. 2. Every Member State is legally obligated to pay its respective share of finances towards peacekeeping operations. 3. Currently, Indian personnel are deployed in all active UN peacekeeping missions.How many of the above given statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (A) Only one
    Explanation

    Option a is the correct Peacekeeping is one of the most effective tools the United Nations in the promotion and maintenance peace and security. The first UN was established in May 1948, when the UN authorized the deployment of a small number of observers to the Middle 1 is incorrect: The UN can only deploy when there is a UN Security Council (Not Assembly) resolution authorizing them to If the Security Council determines that deploying a operation is the most appropriate step to will formally authorize this by adopting a resolution sets out the operation's mandate and size, the tasks it will be responsible for performing. and resources are then subject to General 2 is correct: While decisions about or expanding a peacekeeping operation are the Security Council, the financing of UN is the collective responsibility of all UN Fo { } Every Member State is legally obligated to pay share towar

13. #173Full-length test
    With reference to nuclear technology consider the following statements: 1. Nuclear fuel like U-235 can be used directly to produce electricity. { } 2. Currently Nuclear power reactor produces energy through process of nuclear fusion only. 3. Solid graphite can be used as a moderator in nuclear reactors. 4. Nuclear technology can be used in medical diagnosis and treatment.How many of the above given statements are correct?
    • AOnly one
    • BOnly two
    • COnly three
    • DAll four
    Answer: (B) Only two
    Explanation

    Option b is the correct 1 is incorrect. U-235 cannot be used produce electricity they have to undergo before being used to generate 2 is incorrect. Nuclear fusion-based are presently not in operation for meeting needs on a commercial scale. However, some power plants are under construction around More common ones are the nuclear fission 3 is correct. Water, solid graphite and are used as a moderator in nuclear 4 is correct. Nuclear technology can be medical diagnosis and treatment. It can also be used 11 Fot { - 5 in different industries for different purposes such as in of food, sterilization of disposable products etc. i J Important Tips Operational Inda and their states Name Of Nuclear Station Kakrapar Atomic Power Station - 1993 Gujarat (Kalpakkam) Madras Atomic Power Tamil Nadu Station - 1984 Narora Atomic Power Station- 1991 Uttar Pradesh Kaiga Nuclear Power Plant -2000 Karnataka R

14. #174Full-length test
    With the present state of technological development, Machine Learning can effectively do which of the following? 1. Translation of languages 2. Developing Self-driving cars 3. Diagnosis of some diseases 4. Detection of energy theft in Smart Power grids. 5. Wireless Charging of Electric Vehicles.Select the correct answer using the code given below
    • A1, 2 and 4 only
    • B1, 2, 3 and 4 only
    • C2, 3 and 5 only
    • D1, 2, 3, 4 and 5
    Answer: (B) 1, 2, 3 and 4 only
    Explanation

    Option b is the correct learning is a branch of artificial intelligence computer science which focuses on the use of data to imitate the way that humans learn, its accuracy { 1 is correct: Machine learning can be translate languages effectively. For instance, AI has introduced the machine translation (MMT) model that between any pair of 100 languages without English 2 is correct: Machine learning can be in developing Self driving cars. enables self-driving cars to gather data about and learn from it. For example the the brake to be automatically applied once the a red light (traffic signal) in the 3 is correct: Machine learning can be used diseases in humans. For example, a technology using Machine learning to in the human eye which can reveal signs of like 4 is correct: Machine learning (ML) can be detect energy theft in smart power grids by consumption 5 is incorrect: At present, Machi

15. #175Full-length test
    Consider the following statements with reference to INS Vikrant: 1. It is the only functional Aircraft carrier in India. 2. It is India's first indigenously. designed and manufactured aircraft carrier. 'Festbook { } 3. It uses the Short Take Off but Arrested Recovery (STOBAR) model for launching the aircrafts.Which of the statements given above are correct?
    • A1 and 2 only
    • B1 and 3 only
    • C2 and 3 only
    • D1, 2, and 3
    Answer: (C) 2 and 3 only
    Explanation

    Option c is the correct commissioning of India's first Indigenous (IAC-1) into the Navy as INS Vikrant marks moment for l is incorrect: INS Vikrant is not the Aircraft carrier in India. Apart from the other functional aircraft carrier is Russian origi.r, Kiev-dus INS Vikramaditya. Russia's Gorshkov was commissioned into the Indian INS at Severodvinsk, Russia on 2 is The first ever aircraft carrier to designed and cmi.structed, INS Vikrant the as a 'Blue Water Navy' force with reach and capability to deep seas. It has an overall indigenous content of 3 is coned: INS Viknmt uses a novel aircraft operation mode known as STOBAR (Short Take- Off Landing), the IAC is equipped with a ski launching aircraft, and a set of 'arrester wires' for onboard. In this type of the frontal the deck is elevated forming a curve. This is called Thus, when an aircraft leaves the deck at the the runway, it doesn

16. #176Full-length test
    Which of the statements is correct regarding the speed of sound?
    • ASound travels faster in cold air thari in hot air, keeping other things constant
    • BSpeed of sound is same throughout the medium even when it travels through materials with different elasticity
    • CDensity of a material has no direct correlation with speed of sound in the same medium
    • DNone of the above
    Answer: (D) None of the above
    Explanation

    Option d is the correct a is incorrect. Heat, like sound, is a form of Molecules at higher temperatures have more they can vibrate faster. Since the molecules vibrate waves can travel more quickly. Therefore, Sound faster in Hot air rather than cold b is incorrect. The speed of sound is different types of solids, liquids and gases. Thus, the sound is not constant throughout the medium. One primary reasons is elastic properties are different c is incorrect. The density of the medium affects of sound. Sound will travel at a slower rate in object if they have the same elastic properties. and Gold-The speed of sound will be higher as its density is less than Gold

17. #177Full-length test
    Which of the following statements correctly defines the term "Chemosynthesis"?
    • AIt is the process by which certain microbes create energy by mediating chemical reactions
    • BIt is defined as directional cell movement of cells towards concentration gradients of solubilized attractants
    • CIt is defined as random cell movement in the absence of chemoattractant gradients
    • DIt is a drug treatment that uses powerful chemicals to kill fast-growing cells in your body
    Answer: (A) It is the process by which certain microbes create energy by mediating chemical reactions
    Explanation

    Option a is the correct life on Earth is dependent upon process by which plants make energy from at hydrothermal vents in the deep ocean a has evolved in the absence of sunlight, and of energy is completely different: is the process by which certain energy by chemical reactions. microbes provide the foundation colonization of vents. Chemosynthetic on or below the seafloor, and even within the bodies vent animals as symbionts

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