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Physics — UPSC Prelims Science & Environment previous year questions — page 4

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. #121Practice set
   Which of the following animals can produce infrasonic sound? 1. Whales 2. Elephants 3. Bats 4. Rhinoceros 5. DolphinsSelect the correct answer from the codes given below
   • A1, 2 and 3 only
   • B1, 2 and 4 only
   • C2, 3 and 5 only
   • D1, 4 and 5 only
   Answer: (B) 1, 2 and 4 only
   Explanation

   Option b is the correct audible range of sound for human beings extends 20 Hz to Hz. The sound of frequencies Hz are called infrasonic sound or infrasound. of frequencies above Hz are called or ultrasound. Hence, both infrasonic sounds are inaudible to I is correct: Whale can vocalize and hear very low pitched, or infrasonic sound, using which they can distances and scatter to large areas in water. sound, whales can communicate with each geographic areas as large as an ocean 2 is correct: Elephants can produce and using very low frequency sounds, below the range of human hearing. These low frequency infrasound can travel several kilometres elephants with a "private" communication plays an important role in elephants' complex social 3 is incorrect: Bats do not produce they use ultrasonic waves Hz) and 4 is correct: Rhinoceros can produce of frequency as low as 5 Hz for 5 is incorrect: Dol

2. #122Practice set
   With reference to the 'Total Solar Eclipse', consider the following statements:1. 'Ring of fire' is a unique characteristic of Total Solar Eclipse. 2. Total Solar Eclipse are rare as compared to Total Lunar Eclipse. 3. Total Solar Eclipse provides an opportunity for scientists to study the corona of the Sun.How many of the statements given above are correct?
   • AOnly one
   • BOnly two
   • CAll three
   • DNone uulll
   Answer: (B) Only two
   Explanation

   Option b is the correct solar eclipse occurs when the moon is Earth and the Sun and casts a shadow over Sometimes the Moon only blocks part of the Sun's light. called a partial solar eclipse. There are various types eclipse - Total Solar Eclipse, Annular solar, eclipse and Hybrid solar eclipse. When Moon of the Sun's light. This is called a total solar I is incorrect: 'Ring of fire' is a Annular Solar Eclipse (Not Total Solar Eclipse). solar eclipse occurs when the moon passes sun and Earth when it is near its farthest point At this distance, the moon appears smaller than and doesn't cover the entire face of the sun. ring of light is created around the moon, which known as 'Ring of 2 is correct: Lunar eclipses are more because during a lunar eclipse, Earth casts a shadow on the Moon than the Moon casts during eclipse on Earth. The reason solar eclipses are so that the umbra of the Moon r

3. #123Practice set
   Which of the following is/are the preventive measures taken so that the trains don't topple when moving along a curved track? 1. The curved railway tracks are slightly inclined. 2. The shape of wheel is made slightly conical. 34.Select the correct answer using the code given below
   • A1 only
   • B2 only
   • CBoth 1 and 2
   • DNeither 1 nor 2
   Answer: (C) Both 1 and 2
   Explanation

   Option c is the correct implies that an object or an item will over. Trains can topple over curved surfaces if tracks without using proper 1 is correct: The reason for trains don't moving along a curved tracks because railway banked. The outer rail is positioned at a slightly than the inner one. This is the reason why often inclined. Because of the inclination (due to the normal force (reaction of the from the ground has a horizontal component. as this equals the centripetal force of the curve at the train does not fall 2 is correct: The wheels on each side of a train connected with a metal rod called an axle. This axle two train wheels moving together, both wheel turning same speed when the train is moving. This great for straight tracks. But when a train needs to a bend the fact that both wheels are always the same rate can become a problem. The outside of is slightly longer than the i

4. #124Practice set
   The device not require any input energy to operate. Select the correct answer using the code given below
   • A1 only
   • B2 only
   • CBoth 1 and 2
   • DNeither 1 nor 2
   Answer: (A) 1 only
   Explanation

   Option a is the correct Neutrino Observatory (INO) is a proposed research mega project. The objective of the to study neutrinos in a cave. is proposed to be set up near Bodi West hills village in Theni district in Tamil I is correct: The India-based (INO) needs to be underground in order background noise and increase the sensitivity of Neutrinos are subatomic particles that are detect because they interact very weakly with 2 is incorrect: The underground not preserve the physical properties of neutrinos are not affected by atmospheric matter. Neutrinos particles that interact very weakly with matter, can pass through large amounts of rock and soil 3 is incorrect: Neutrinos do not require vacuum like conditions to react with other atoms and it can in underground as well as in the underground detectors are more advantageous detection than atmospheric detectors because location helps to red

5. #125Practice set
   In which of the following medium Sound cannot travel- !. Air 2. Water 3. Vacuum 4. DiamondWhich of the above statements is/are correct in the above context?
   • A1 and 2 only
   • B3 only
   • C3 and 4 only
   • D1, 3 and 4 only
   Answer: (D) 1, 3 and 4 only
   Explanation

   Option d is the correct answer e l 9 p examples of evaporation in daily life with clothes i n the sun: The water present in the hen they are washed removed by the process ration. zation:' Crystallization is th'.e process of obtaining from the ""mother" liquid. It takes place due to ion.poration process is used in food processing to process milk. pasta, and other fruit O btained either from a natural process or industrial process, evaporation is of an ice cu be is an example of of acetone -w-hich is used for removing e-veryday example of is the process in -which two. mixtures -w-ith the help of evaporation as boiling of is of samples in with the help of rotary evaporators everyday example of evaporation is the body after -w-et floors is also an example of evaporation. Iin.portant takes place -w-hen the particles of the liquid changes into gaseous phase. It is a as only the liquid particle

6. #126Practice set
   With reference to the Dark Sky Reserves, consider the following statements. 1. It is an area where light pollution is monitored, to allow better observation of sky at night. 2. A Dark Sky Reserve is to be set up at Hanle in Ladakh.Which of the above statements 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 dark-sky preserve (DSP) is an area, usually park or observatory that is kept free of artificial The purpose of a dark sky preserve is generally 1 is correct: A dark sky reserve is an area pollution is monitored. Basically, there are around the reserve where humans are to have any loud source of light. So, it allows of skies at night for 2 is correct: Recently, in a the Department of Science Technology announced the setting up of India's first Dark in Hanle, Ladakh. Hanle, which is about above sea level, hosts telescopes and is one of the world's most optimal sites for

7. #127Practice set
   Consider the following statements about Geomagnetic Storm: 1. A geomagnetic storm is a disturbance of the Earth's magnetic field caused by solar emission like Coronal Mass Ejections. 2. A Geomagnetic storm can lead to the occurrence of high-rise tsunamis on Earth. 3. The severity of geomagnetic storms is ranked by the World Meteorological Organization.How many of the statements given above are correct?
   • AOnly one
   • BOnly two
   • CAll three
   • DNone I 1
   Answer: (A) Only one
   Explanation

   Option a is the correct geomagnetic storm is a major disturbance of that occurs when there is a very of energy from the solar wind into the surrounding Earth. These storms result in the solar wind that produces major changes currents, plasmas, and fields in Earth's 1 is correct: According to NASA, a refers to the disruptions to the Earth's magnetic by solar emissions. When a Coronal Mass or a high-speed solar stream reaches our planet, into the magnetosphere. The Earth's created by our magnetic fields, and it usually protects the particles emitted by the 2 is incorrect: According to the and Atmospheric Administration (NOAA), storm or a solar storm does not directly occurrence of tsunamis on the Earth. For a tsunami to on Earth, there has to be an earthquake the ocean floor that displaces water and generates ultra-fast wave through the entire water 3 is incorrect: The severity of is NOT r

8. #128Practice set
   In the context of modern scientific research, consider the following statements about the 'Square Kilometre Array': 1. It will be the world's largest optical telescope positioned in the Arctic region. 2. It will enable the scientists to study the origin and evolution of galaxies.Which of the statements given above is/are correct?
   • A1 only
   • B2 only
   • CBoth 1 and 2
   • DNeither 1 nor 2
   Answer: (B) 2 only
   Explanation

   Option b is the correct 1 is incorrect. A new called Square Kilometre Array Council has approved the building of the radio telescope, Square Kilometre Array (SKA). will consist of a vast array of radio receivers be positioned across South Africa and is participating in SKAO through the Department Energy (DAE) and the Department of Science 2 is correct. SKA will allow astronomers deeper into the universe and unravel secrets about Among its goals are: studying the universe evolution, the origin and evolution of cosmic dark energy and evolution of galaxies. It will of the biggest questions about the nature of energy, and how galaxies formed and Scientists are also optimistic that the SKA will to detect very weak extra-terrestrial signals and molecules that support life

9. #129Practice set
   There is a growing interest in the exploration of Moon's South Polar Region. What is the importance of this region of the Moon? 1. It is estimated to hold a large amount of water. 2. It offers an opportunity to have a better understanding of the solar system's origin. 3. Its regolith has traces of some of the essential resources.Select the correct answer using the code given below
   • A1 and 2 only
   • B2 and 3 only
   • C3 only
   • D1, 2 and 3
   Answer: (D) 1, 2 and 3
   Explanation

   Option d is the correct 1 is correct. The permanently shadowed the South Polar Region of Moon are estimated to I 00 million tons of 2 is correct. Its craters have been sunlight for billions of years - offering an of the solar system's elemental and positional advantages make it a suitable for future space 3 is correct. Its regolith has traces of methane, sodium, mercury, and silver - an untapped source of essential resources

10. #130Practice set
    Regarding the Lagrange points in space, consider the following statements: 1. Lagrange Points are positions where the gravitational forces of a two-body system produce enhanced regions of attraction and repulsion. 2. There are three Lagrange points in the Earth- Sun system. 3. These points are used by spacecraft to reduce fuel consumption needed to remain in position. 4. 12 Lagrange point of the Earth-Sun system is ideal for solar observatories as it gets an uninterrupted view of the sun.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • COnly three
    • DAll four
    Answer: (B) Only two
    Explanation

    Option b is the correct l is correct. Lagrange Points are positions where the gravitational forces of a two-body the Sun and the Earth produce enhanced regions and points is a position where the gravitational two large masses precisely equals the centripetal for a small object to move with 2 is incorrect. There are five Lagrange the Earth- Sun system where a small mass can orbit in 3 is correct.Lagrange,Points are where the gravitational forces of a the Sun and the Earth produce and repulsion. These can be used by spacecraft fuel consumption needed to remain in positfor Statement 4 is incorrect. The LI point of the affords an uninterrupted view of the sub. 'and' home to the Solar and Heliospheric The third Lagrange point, L3, remains. the Sun at all times, opposite Earth's has not found a use for this spot

11. #131Practice set
    A ramjet is a variant of jet engine that are used in space missions. What is its significance? 1. They work most efficiently at hypersonic speeds. 2. They are mostly employed for movement in vacuum conditions. 3. They can quickly move an aircraft from standstill to very high acceleration.Select the correct answer using the code given below
    • A1 and 3 only
    • B2 and 3 only
    • C1 only
    • DNone of the Above
    Answer: (D) None of the Above
    Explanation

    Option d is the correct 1 is incorrect. A ramjet is a form of engine that uses the vehicle's forward motion to air for combustion without a rotating work most efficiently at supersonic speeds 3 (three times the speed of sound) and can operate speeds of Mach 6. However, the ramjet efficiency starts when the vehicle reaches hypersonic 2 is incorrect. Ramjets cannot work in vacuum is a form of air-breathing jet engine that uses the motion to compress incoming air for a rotating compressor. Fuel is injected in chamber where it mixes with the hot and 3 is incorrect. Ramjets cannot produce thrust airspeed; they cannot move an aircraft from a ramjet-powered vehicle, therefore, requires an like a rocket assist to accelerate it to a speed where to produce thrust. Important Tips A scramjet engine is an improvement over the ramjet engine as it efficiently operates at hypersonic speeds and allows su

12. #132Practice set
    Consider the following statements with reference to Dark Matter, sometimes seen in news: 1. Dark matter does not absorb, reflect or emit light. 2. Dark matter interacts with the rest of the universe only through its gravity. 3. Dark matter is a category of antimatter.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone i i
    Answer: (B) Only two
    Explanation

    Option b is the correct visible universe including Earth, the sun, other galaxies is made of protons, neutrons, and together into atoms. They make up only of astronomers theorize that the faster expansion rate Universe is due to a mysterious, dark force or is pulling galaxies apart. The term 'dark' is used the 1 is correct. Dark matter is a mysterious composes about of the makeup of the normal matter, dark matter does not interact electromagnetic force. This means it does not or emit light, making it extremely hard to detect. researchers have been able to infer the existence of only from the gravitational effect it seems to have on fast rotation is ortly,whert there is mote. that extra mass is believed to come from dark matter. 2 is correct. Dark matter interacts with the the universe only through its gravity (that's how it exists). Many large lab experiments have tried elementary partic

13. #133Practice set
    With reference to proton therapy, consider the following statements: 1. It is a type of radiation therapy which uses protons to treat cancer. 2. In this therapy, protons do not exit the target tumor and the healthy tissue stays unaffected. 3. The positive charge on a proton is equal in magnitude to the negative charge on an electron.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone ook
    Answer: (C) All three
    Explanation

    Option c is the correct answer. Statement 1 is correct. Proton therapy, also called proton beam therapy, is a type of radiation therapy. It uses protons rather than x-rays to treat cancer. A proton is a positively charged particle. At high energy, protons can destroy cancer cells. Doctors may use this therapy alone. They may also combine it with x-ray radiation therapy, surgery, chemotherapy, and/ or immunotherapy. Statement 2 is correct. In regular radiation therapy, the beam of energy goes into the body, through the tumor, and out the other side. This "exit dose" of radiation might affect healthy tissue beyond the tumor. In proton therapy, after delivering the energy to the tumor, the protons stop. They do not exit the tumor and go into healthy tissue on the other side. In this way, proton therapy reduces radiation exposure and potential damage to healthy tissue, especially in sensitiv

14. #134Practice set
    Consider the following statements with reference to food irradiation: 1. Gamma irradiation is used for insect disinfestation of cereals, pulses and grains. 2. The Codex Alimentarius Commission and Codex Standards recommends the complete ban on irradiation of food items. 3. Food Irradiation can delay ripening of fruits and store foods for years without refrigeration.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (B) Only two
    Explanation

    Option b is the correct irradiation is a technology in which food products to a low dosage of radiation to treat them for insects, increasing their longevity and shelf life. It is of ionizing radiation to food in which transmitted without direct contact in the targeted The radiation can be emitted by a radioactive substance 1 is correct. Gamma Irradiation is the process various products to ionizing gamma rays UV and X-rays) in a highly controlled manner. It is a specific goal, such as elimination of the virus, insects and other undesirable organisms etc. It for inhibition of sprouting in bulbs and tubers, of cereals, pulses and grains, of dry spices etc. for extension by applying pre-determined radiation isotope Cobalt-60 is the most common source rays for irradiation processing for a variety including sterilization, decontamination 2 is incorrect. The Codex the highest international bod

15. #135Practice set
    Which of the following can be the possible use of Magnetism in medicine? 1. Imaging diagnosis of the whole-body system. 2. Mass spectrometers. 3. Treatment of Parkinson's disease. 4. Treatment of depression.Select the correct answer using the code given below
    • A1, 2 and 3 only
    • B2, 3 and 4 only
    • C1, 2, 3 and 4
    • D1, 3 and 4 only
    Answer: (C) 1, 2, 3 and 4
    Explanation

    Option c is the correct answer Weak ion currents that travel along the nerve cells in our body produce magnetic fields because an electric current always produces a magnetic field. Option correct The magnetic field inside the body forms the basis of obtaining the images of different body parts. This is done using a technique called Magnetic Resonance Imaging (MRI). Analysis of these images helps in medical diagnosis. Option 2 is correct. Mass spectrometry, also called mass spectroscopy, analytic technique by which chemical substances are identified by the sorting of gaseous ions in electric and magnetic fields according to their mass-to- charge ratios. Clinical' mass spectrometry uses the mass spectrometry technology for diagnostic purposes. It is used to diagnose metabolism deficiencies, to determine whether biomarkers or enzymes are present, and for toxicology testing. Option 3 is corr

16. #136Practice set
    "Stethoscope is a medical instrument. It is generally used by the doctors for listening to the sounds produced within the human body mainly in the heart and lungs. In stethoscopes, doctor listens to the sound of the patient's heartbeat?' Based on above paragraph, which physical principle is used by stethoscopes to listens to the sound of the patient's heartbeat:'
    • ADoppler effect
    • BTyndall effect
    • CMultiple Reflection of sound
    • DPrinciple of ultrasound mllll
    Answer: (C) Multiple Reflection of sound
    Explanation

    Option c is the correct answer. When the sound is reflected more than once and the repeated reflection that results in the persistence of sound is called multiple reflection. Stethoscope is a medical instrument used for listening to sounds produced within the body, mainly in the heart or lungs; In stethoscopes the sound of the patient's heartbeat reaches the ears by multiple of sound. Important Tips Doppler effect means the apparent change in the frequency of the light observed by the observer due to relative motion between the source of light and the observer. Tyndall effect means the scattering of light by very small particles suspended in a gas or liquid. Principle of ultrasound - Ultrasound is an imaging technique where high-frequency sound waves (2- are used to generate an image

17. #137Practice set
    Which of the following are applications of ultrasound? 1. used in welding of thermoplastics. 2. to detect the presence of the flaw or defect in metal blocks. 3. used in humidifiers to spray the water. 4. used by animals to detect their prey. 5. in radar surveillance to determine the speed of automobiles. Select the correct answer using the code given below
    • A1, 2 and 5 only
    • B1, 2, 3 and 4 only
    • C3, 4 and 5 only
    • D2, 3 and 5 only
    Answer: (B) 1, 2, 3 and 4 only
    Explanation

    Option b is the correct are high frequency waves. Ultrasounds are travel along well defined paths even in the presence 1 is correct. Ultrasonic welding uses at high frequencies (20-40 to produce (1-25 µm) mechanical vibrations. These heat at the joint interface of the parts being resulted in melting of the thermoplastic materials formation after 2 is correct. Ultrasonic waves are allowed through the metal block and detectors are. used the transmitted waves. If there is even a small ultrasound gets reflected back indicating the the flaw or 3 is correct. An ultrasonic humidifier is a uses a metal or ceramic "diaphragm" to produce diaphragm vibrates against the water, creating are blown out into your room as a fine 4 is correct. The process in which sound echoes are used to determine objects in space is Bats emit sound waves that lie in frequency range from their mouth and sound waves hit t

18. #138Practice set
    In the context of Food irradiation, consider the following statements: 1. Gamma rays emitted from Cobalt 60 can be used for food irradiation. 2. Perishable items like fruits and vegetables cannot be preserved using food irradiation. 3. Irradiation noticeably change the taste, texture, or appearance of food items. Fo L [ ]How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (A) Only one
    Explanation

    Option a is the correct irradiation (the application of ionizing radiation is a technology that improves the safety and extends of foods by reducing or eliminating 1 is correct. There are three sources of for use on rays are emitted from radioactive forms of cobalt (Cobalt 60) or of the element cesium Gamma radiation is used routinely to sterilize and household products and is also used for treatment of are produced by reflecting a high-energy stream off a target substance (usually one of the into food. X-rays are also widely used in industry to produce images of internal beam (or e-beam) is similar to X-rays and is of high-energy electrons propelled from an into 2 is incorrect. Items like fruits, potatoes, herbs and some ready-to-eat foods can be food 3 is incorrect. Irradiation does not make compromise nutritional quality, or the taste, texture, or appearance of food. In fact, made by

19. #139Practice set
    Consider the following statements with respect to cryopreservation and food irradiation: 1. Cryopreservation is a technique of preserving cells and tissue at very low temperature. 2. Food irradiation is the process of passing the food through high energy electrons to eliminate microorganisms from it. 3. While cryopreservation preserves food without compromising its nutritional content, irradiation compromises the nutritional quality of food.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (B) Only two
    Explanation

    Option b is the correct is a technique in which low used to preserve the living cells and tissue while is a process that uses radiation to control pests and prevent 1 is correct. Cryopreservation is a process organelles, cells, tissues, or any other by cooling the samples to very low maintain their viability. The word cryo comes from word "kayos" meaning "frost". It means a "frozen state". Cryopreservation uses liquid nitrogen and thus preserve, biological 2 is correct. Food irradiation (the application radiation to food) is a technology that safety and extends the shelf life of foods by reducing microorganisms and insects. During rays, x-rays, or high-energy electrons pass food, destroying or inactivating bacteria and viruses foodborne 3 is incorrect. Preservation of food delays spoilage and keeps foods preventing microorganisms from growing and down the enzyme activity that causes food

20. #140Practice set
    Which of the following statements is/are incorrect about hydrogen energy? l. Hydrogen gas is extracted from water using the technique of electrolysis. 2. The efficiency of a hydrogen cell is less than that of an internal combustion engine. Practkebook,11 3. Hydrogen energy does not emit any greenhouse gas into the environment. 4. Hydrogen fuel only produces electrical energy which can be used as an energy source. Select the answer using the code given below
    • A1 and 4 only
    • B1, 2 and 3 only
    • C2, 3 and 4 only
    • D1, 2, 3 and 4
    Answer: (C) 2, 3 and 4 only
    Explanation

    Option c is the correct 1 is correct. Hydrogen gas is extracted by a technique known as electrolysis, which a high electric current through water to and oxygen atoms. The electrolysis process expensive since it involves high energy 2 is incorrect. Hydrogen fuel cells are than internal combustion engines. batteries are still the most energy efficient highest performing energy 3 is incorrect. Hydrogen energy is renewable a minimal environmental impact, but its separation requires other non-renewable sources such as and natural gas. Fossil fuels are still needed to fuel which leads to emission of greenhouse 4 is incorrect. The hydrogen gas can also just (mechanical energy and not just electrical power vehicle engines. The by-products of this are water and carbon that is used to and Fo

21. #141Practice set
    With reference to Geothermal Energy consider the following statements: 1. It is the energy that is generated from the heat within the Earth. 2. Active Geothermal resources are usually concentrated along major plate boundaries. 3. Puga and Surajkund are important sites for geothermal energy in India.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (C) All three
    Explanation

    Option c is the correct 1 is correct. Geothermal energy is the generated and stored inside the Earth's crust. water comes in contact with the hot is 2 is correct. The most active are usually found along major plate earthquakes and volcanoes are 3 is correct. Puga in Jammu Kashmir in Jharkhand are important sites for in India. Other important sites are Tattapani in Chhattisgarh Cambay Graben in Gujarat Manikaran in Himachal Pradesh Chhumathang in Jammu

22. #142Practice set
    It is a device that converts chemical energy to electrical energy by the action of microorganisms and uses bacteria as the catalyst to oxidize organic and inorganic matter to generate electric current. It has applications in various fields such as power generation systems, bio-recovery, and waste-water treatment. The device mentioned here is
    • ABio-electrification
    • BMicrobial Fuel cell
    • CBio-synthesis
    • DMicrobial accumulation '
    Answer: (B) Microbial Fuel cell
    Explanation

    Option b is the correct Fuel cell is a device that converts chemical electrical energy by the action of microorganisms bacteria as the catalyst to oxidize organic and to generate electric current. It has various fields such as power generation systems, bio recovery, and waste-water treatment. Important Tips Bioelectricity is the electrical currents and potentials generated by or occurring within living cells, tissues, and organisms. The creation of an organic compound in a living organism is referred to as biosynthesis. Biosynthe.sis refers to the production of a complex chemical compound from simpler precursors in a living organism. It is usually involving enzymes that will catalyze the reaction) and energy source (e.g TP). Examples of biosynthesis include photosynthesis

23. #143Practice set
    Wi.th reference to nuclear technology comiider the following statements:1. lfodear fuel like U-235 can be used directly to produce electricity. 2. Currentiy 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 ab ave 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 directly electricity they have to undergo enrichment being used to generate 2 is incorrect. Nuclear fusion-based power presently not in operation for meeting the energy some nuclear fusion-based power plants are around the world. More common ones fission 3 is correct. Water, solid graphite and heavy used as a moderator in nuclear 4 is correct. Nuclear technology can be medical diagnosis and treatment. It can also be used. industries for different purposes such as in of food, sterilization of disposable products etc

24. #144Practice set
    What are. the advantages of floating solar energy plants? 1. Increased Efficiency of a Solar Panel 2. Lower cost of Installation 3. Lower evaporation of water bodies.Select the correct statement using the code given below
    • A1 and 2 only
    • B2 and 3 only
    • C1 and 3 only
    • D1, 2 and 3 only
    Answer: (C) 1 and 3 only
    Explanation

    Option c is the correct 1 is correct. Solar Panels are durable and can high temperatures. But same as other electronics, temperatures, come with decreased power efficiency of a solar panel tends to decrease as rise, which can be concerning for who are looking to get a solar panel installation hot and sunny climate. The bodies of water that host solar panels will help the solar-powered down, which means that the floating solar will increase the efficiency of a solar panel hot climates than they otherwise 2 is incorrect. A floating solar panel additional costs than more traditional solar Because this is a relatively new solar it requires specialized solar power more niche solar panel installation knowledge, it require a higher price tag than installing a similar sized solar power farm on a rooftop, or solid 3 is correct. The floating solar panel shade to the body of water and reduces from

25. #145Practice set
    Consider the following statements with respect to Lithium -ion (Li-ion) batteries: 1. These are rechargeable batteries with very high energy density. 2. At their present stage of development, these batteries are a viable alternative to internal combustion engines in manufacturing of electric vehicles. 3. Cost manufacturing of these batteries is less than nickel based batteries.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (D) None
    Explanation

    Option d is the correct 1 is incorrect: Lithium ion batteries batteries with a weak energy density. The of electrolyte, which allows for ionic the two electrodes are the constituent components of battery 2 is incorrect: Lithium-ion battery made it to being one of the most preferred power dectric and hybrid electric vehicles; however, they the range that would make them a viable alternative combustion 3 is ion batteries are manufacture. They cost about 40 percent higher batteries

26. #146Practice set
    To meet its rapidly growing energy demand, some opine that India should pursue research and development on thorium as the future fuel of nuclear energy. In this context, what advantage does thorium hold over uranium? L Thorium is far more abundant in nature than uranium. 2. On the basis of per unit mass of mined mineral, thorium can generate more energy compared to natural uranium. 3. Thorium produces less harmful waste compared to uranium.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (C) All three
    Explanation

    Option c is the correct 1 is correct. Thorium is 3 times as abundant almost matching the amount of lead and gallium Earth's crust. Thorium composes of the whereas Uranium composes of earth's a substantial amount of Uranium is found in 2 is correct. On the basis of per unit mass mineral, thorium can generate more energy natural uranium. It is estimated that one ton of produce as much energy as 35 tons of uranium in a thorium reactor. Conventional reactors than one percent of uranium, whereas a well reactor can utilize of its thorium when comparing breeder reactors for Uranium the energy per kilogram would be 3 is correct. Thorium produces less compared to uranium. There is up to two orders less of nuclear waste in the liquid fluoride eliminating the need for large scale and for the waste. This is because the cycle does not irradiate U-238, so it does not bigger than uranium. Furthermore,

27. #147Practice set
    Which of the following are the methods used for Waste to energy conversion? 1. Torrefaction 2. Polycrack 3. Soil Liquefaction 4. PulverizationSelect the correct answer using the code given below
    • A1 and 2 only
    • B2, 3 and 4 only
    • C4 only
    • D1 and 3 only
    Answer: (A) 1 and 2 only
    Explanation

    Option a is the correct can be generated in form of electricity and/or the primary treatment of waste. It is done or Energy-from-Waste is of energy recovery and the process of generating in the form. of electricity and/ or heat by processing of a fuel source. There are various kind of Waste to as 1 is correct. The torrefactiontechnology straw, grass, sawmill residue, and wood biomass degrees Celsius - 350 degrees Celsius. This changes of the biomass into 'coal-like' pellets. Thes.e be used for combustion along with coal for like steel and cement 2 is correct. Polycrack technology is the patented heterogeneous catalytic process that feedstocks into hydrocarbon liquid fuels, and water. The process is a closed-loop system not emit any hazardous pollutants into the combustible, non-condensed gases are re-used energy to the entire system and thus, the comes from the combustion of gaseous proc

28. #148Practice set
    Consider the following statements about Directed Energy Weapons (DEWs) and Hypersonic Weapons: 1. DEWs use directed energy in the form of laser, microwave, or particle beams to destroy targets. 2. DEW are much cheaper to produce when compared with traditional kinetic weapons. 3. Hypersonic weapons travel at speeds greater than Mach 5. 4. Hypersonic cruise weapons have fixed trajectories and limited maneuverability.How many of the statements given above are correct?
    • AOnly one
    • BOnly two
    • COnly three
    • DAll four
    Answer: (B) Only two
    Explanation

    Option b is the correct Energy Weapons (DEWs) are a ranged weapon its target with highly focused energy without a including lasers, microwaves, particle beams beams. Hypersonic weapons are weapons capable at hypersonic speed, defined as between five times the speed of 1 is correct: DEWs use directed energy in of laser, microwave, or particle beams to These weapons are designed to damage or by emitting highly focused energy in the form microwaves, or particle 2 is incorrect: DEWs can be expensive to maintain compared with traditional kinetic weapons require complex and advanced 3 is correct: Hypersonic weapons are can travel at speeds of Mach 5 to Mach 10, which is ten times the speed of sound. These weapons can be strike targets with high precision and at long 4 is incorrect: Hypersonic cruise weapons manoeuvrable and able to change course They are different from ballistic missiles, whic

29. #149Practice set
    With reference to Microwave Weapons, consider the following statements: 1. They are direct energy weapons which aims a highly focused energy at a target. 2. It uses electromagnetic radiation to heat the water in a human target's skin.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. Microwave weapons aim energy in the form of sonic, laser, or at a 2 is correct. Microwave weapons use a of high-frequency electromagnetic radiation the water in a human target's skin, causing pain The process is similar to microwave electromagnetic waves are used to agitate the in the food and the vibration produces heat the food

30. #150Practice set
    In the context of Indian defence, what is 'Rudram-I'? 1. It is India's first indigenous anti-radiation missile. 2. It is a supersonic surface-to-air missile with a range of 30 km.Which of the statements given above is/are correct?
    • A1 only
    • B2 only
    • CBoth 1 and 2
    • DNeither 1 nor 2
    Answer: (A) 1 only
    Explanation

    Option a is the correct 1 is correct. The Defence Research Organisation (DRDO) has successfully indigenously developed Anti-Radiation It is the first indigenous anti-radiation 2 is incorrect. It is an air-to-surface missile strike range of around 100 to 150 km. It has been by DRDO

31. #151Practice set
    Consider the following statements: 1. Project 17 A involves manufacturing of indigenous fighter aircrafts for the Indian air force. 2. All materials required under Project 17 A are to be procured indigenously. 3. Project 75 includes building six scorpene class attack submarines for the Indian Navy.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (A) Only one
    Explanation

    Option a is the correct l is incorrect. Under the Project 17 A, a total stealth frigates at an estimated cost of Rs 50,000 be built. The project was cleared by the Government in 2015. These ships are being built with features, advanced indigenous weapon and sensor with several other 2 is incorrect. Under Project 17 A, of equipment required (not completely) for are sourced from indigenous vendors and and MSMEs within the 3 is correct. Project 75 is the programme by Navy to build six Scorpene-Class attack. will also feature advanced air-independent This is for enabling them to stay submerged duration and substantially increase their The six submarines are - INS Kalvari, INS Karanj, INS) Vagir, INS Vela and INS Vagsheer

32. #152Practice set
    Consider the following statements with reference to the'term "Micro-LED": 1. Only organic materials are used for the manufacturing of Micro- LEDs. 2. The LED used in this technology is self illuminating. 3. They have brighter and better color reproduction than OLED display technology.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 1 is incorrect: Micro LED differs from OLED makeup of the LED materials. The O in OLED for organic and refers to the organic materials used in part of the pixel stack. this to an inorganic Gallium Nitdde which is typically found in regular LED 2 and 3 are correct: Micro-LEDs are self illuminating diodes that have brighter and better than Organic Light Emitting Diode LED TVs can be made up of a number of that attach together to form a bigger screen like from Transformers. One can buy a couple to make a smaller TV, and then add more if into a bigger house with more space for a TV. Important Tips Micro LED is a display technology that uses arrays of tiny LEDs as pixels in a display. These LEDs are much smaller than the ones used in traditional LED displays, which allows for higher resolution, finer image fidelity and more compact displays

33. #153Practice set
    Consider the following statements regarding types of food chains: 1. In the grazing food chain the primary source of energy is living plant biomass while in the detritus food chain the source of energy is dead organic matter or detritus. 2 Detritus food chain is totally independent of grazing food chain. Which of the statements given above is/are c.orrect? Both 1 and 2 1 nor 2 62. With reference to detritus food chain, consider the following: 1. Bacteria and fungi obtain energy by decomposing dead organic substances. 2. It helps in recycling inorganic nutrients. of the statements given above is/are correct?
    • A1 only
    • B2 only (c) Both 1 and 2
    • CBoth 1 and 2
    • DNeither 1 nor 2 61
    Answer: (C) Both 1 and 2
    Explanation

    Option c is the correct l is incorrect. Not all electromagnetic the earth's surface. Radio frequencies, visible some ultraviolet light reach up to sea level. The stops most types of electromagnetic space from reaching Earth's 2 is correct. In an Electromagnetic one moves from gamma rays, X rays to radio waves goes on increasing while the frequency goes 3 is incorrect. Radio waves cannot pass and water as both are electrical conductor free electrons. So, when radio waves hit the wave will bounce back as electrons vibrate and do to pass Important Tips

34. #154Practice set
    Consider the following statements: 1. Only about 10 per cent of the energy is transferred to each trophic level from the lower trophic level. 2. Pyramid of energy isWhich of the statements given above is/are correct?
    • A1 only
    • B2 only
    • CBoth 1 and 2
    • DNeither 1 nor 2
    Answer: (D) Neither 1 nor 2
    Explanation

    Option d is the correct computing enables data to be analysed, processed at the edge of a network. The idea is to data locally closer to where it is stored, in latency rather than send it far away to a of Edge Computing can be realised in vehicles: With edge computing, it will to remove the need for drivers in all trucks front one, because the trucks will be able to each other with ultra-low radio networks and increasingly looking to virtualise parts of their This has both cost and flexibility new virtualised RAN hardware needs to do with a low latency. Operators will therefore servers to support virtualising their RAN close to management: Edge computing can enable city traffic management. Examples of this bus frequency given fluctuations in the opening and closing of extra lanes, and, managing autonomous car patient monitoring: An edge on the hospital process data locally to maintain da

35. #155Practice set
    Consider the following statements: 1. Bioaccumulation is the process by which a pollutant from the enters a food chain. 2. In Biomagnification, there is an in crease in concentration of pollutants from one link in a food chain to another. 3. In for biomagnification to occur, the pollutant must be biologically inactive.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (D) None
    Explanation

    Option d is the correct a is incorrect: Light rays scatter much more (not insufficiently) during the hours of sunset, as the sun is at or below the horizon and can't reach the observer directly rather due to angle, they strike the atmosphere which scatters multiple times before they reach the observer. scattering (called Rayleigh Scattering) of energy, and so low frequency and high (like red and orange) are visible, while high frequency radiation (like blue) is b is incorrect: The concentration of dependent on many factors other than the time of So t.he presence of pollutants is not the sole reason scattering of light rays and its subsequent reddish c is incorrect: The sun emits the entire visible light containing all wavelengths at all. times day. It is the wavelengths which get absorbed and get reflected from our atmosphere that change time of the day and are responsible for the of the

36. #156Practice set
    Consider the following statements about Euphotic Zone: 1. It is the upper layer of the aquatic ecosystems, up to which light penetrates and within which photosynthetic activity is confined. 2. It is also known as hadopelagic zone. 3. The thickness of euphotic zone remains same in all water bodies throughout the Earth. 4. Common species that can be primarily found in euphotic zones are scallops, sea urchins, shrimps, krill, etc.How many of the statements given above are correct?
    • AOnly one
    • BOnly two
    • COnly three
    • DAll four
    Answer: (A) Only one
    Explanation

    Exp) Option a is the correct zone is the uppermost or "well-lit" layer of in which there is sufficient light energy net photosynthetic 1 is correct: It is the upper layer of up to which light penetrates and activity is confined. Both respiration activity take place in this zone. 2 is incorrect: Extending from to about 200 meters, it supports known as epipelagic zone. The in deep ocean trenches below 3 is incorrect: The thickness of the varies with the intensity of sunlight as a season, latitude and water turbidity. The depth zone is different in different water bodies Statement 4 is incorrect: The photic zone is home zooplankton and nekton. Species dinoflagellates, cyanobacteria, and silicoflagellates, along with copepods and other crustaceans can be found Whereas, scallops, sea urchins, shrimps, krill, be primarily found in aphotic zone

37. #157Practice set
    Which of the options given below best describe the term 'winterkill'?
    • ADeath of polar bears due to lack of food resources
    • BLoss of fish in winter because of lack of oxygen
    • CExcessively low temperature in the Polar Regions Leading to loss of life
    • DDeath of plants due to extremely low temperatures
    Answer: (B) Loss of fish in winter because of lack of oxygen
    Explanation

    Option b is correct is the kill is a term used to describe the loss of fish in of lack of oxygen in a water body. Snow cover on water body can effectively cut off light, waters into darkness. Hence photosynthesis stops continues. Thus, in shallow lakes, the depleted. Fish die, but we won't know it until the and we find floating fish. This condition is known kill

38. #158Practice set
    Kelp are large brown algae that grow in oceans and provide shelter for many marine organisms. Consider the following statements with respect to Kelp forests:flle 1. They can be found only in the deep-sea water. 2. They are immune from climate events such as El Nino. 3. Algin, a product derived from Kelps, can be used as food additive.How many of the statements given above are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (A) Only one
    Explanation

    Option a is the correct are large brown algae seaweeds found in the forests are underwater areas with a high density which covers a large part of the world's 1 is incorrect: Kelps are found largely in water. Kelp are large brown algae that live in shallow waters and nutrient-rich waters the shore. Because of their dependency upon light kelp forests form in shallow open are rarely found deeper than 49-131 2 is incorrect: Storms and large weather El Nino, can tear and dislodge the kelp, leaving winter forest to begin its growth again each spring Also like a terrestrial forest, kelp forests experience 3 is correct: Algin is an emulsifying agent extracted from kelp. Algin is mainly as food additive. Also, it finds its use in tire manufacturing, ice-cream industry etc

39. #159Practice set
    Which of the following processes can be used to exploit/ extract biomass-based energy? 1. Bagasse based cogeneration in sugar mills 2. Anaerobic Digestion 3. Gasification 4. PyrolysisSelect the correct answer using the code given below
    • A1 and 2 only
    • B2 and 4 only
    • C1, 3 and 4 only
    • D1, 2, 3 and 4
    Answer: (D) 1, 2, 3 and 4
    Explanation

    Option d is the correct energy is energy generated or produced by living organisms. The most common biomass for energy are plants, such as corn and soy. The these organisms can be burned to create heat into based energy can be extracted through 1 is correct: Bagasse based cogeneration in - Cogeneration in Sugar Mills. Sugar industry has practicing cogeneration by using bagasse as With the advancement in the technology for utilization of steam at high temperature and industry can produce electricity and steam for requirements. It can also produce significant for sale to the grid using same quantity example, if steam generation temperature/pressure from bar to bar, more than of additional electricity can be produced for each ton crushed. The sale of surplus power generated cogeneration would help a sugar mill to improve apart from adding to the power generation the 2 is correct: Biagas is

40. #160Practice set
    With respect to microgrid which of the following statement is incorrect?
    • AIt is a self-sufficient energy system that serves a discrete geographical area
    • BDue to lower servicing area, it has high aggregate technical and commercial losses
    • CIt can be disconnected from central grid and still operate autonomously
    • DA distributed energy system such as a rooftop solar plant does not qualify as a micro grid
    Answer: (B) Due to lower servicing area, it has high aggregate technical and commercial losses
    Explanation

    Option b is the correct !I Mkrogriq 101 What is a a is correct. A microgrid is a self-sufficient that serves a discrete geographic footprint, a college campus, hospital complex, business centre, There are one or more kinds of sources (solar panels, wind turbines, combined power, generators) that produce its b is incorrect. Central grids push electricity plants over long distances via transmission lines. Delivering power from afar is a result electricity dissipates in transit. A this inefficiency by generating power close it serves as a result it decreases the c is correct. A microgrid can be disconnected central grid and. operate independently. This allows them to supply power to their a storm or other calamity causes an outage on d is correct. A key. difference from a system is that a microgrid will keep the when the central grid fails; a solar panel alone Simple back-up generators also

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