UPSC Prelims PYQ › Science & Environment › Physics

Physics — UPSC Prelims Science & Environment previous year questions — page 3

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. #81UPSC CDS 2022
   The twinkling of a star is due to
   • Aatmospheric reflection of starlight
   • Batmospheric refraction of starlight
   • Ccontinuous change in the position of the star
   • Doscillation of starlight
   Answer: (B) atmospheric refraction of starlight
   Explanation

   Option b is the correct twinkling of a star is primarily due to the of starlight. When starlight enters the it encounters variations in air density causing the light rays to bend or refract. in density result in continuous changes in of the starlight, leading to the observed It is important to note that this phenomenon is when observing stars from the Earth's to atmospheric interference. Important Tips Reflection: It occurs when light rays bounce off a surface. A common example is the reflection of light from a mirror or a still body of NOLOGY Refraction: It happens when light rays pass through a medium and change direction due to a change in its speed. A classic example is a drinking straw appears bent when placed in a glass of water. Dispersion: It refers to the separation of light into its constituent colors, resulting in a spectrum. This occurs when light passes through a prism or a

2. #82UPSC CDS 2022
   The pitch of a sound wave depends upon which one of its following characteristics?
   • ASpeed
   • BLoudness
   • CAmplitude
   • DFrequency
   Answer: (D) Frequency
   Explanation

   Option d is the correct pitch of a sound wave is determined by its refers to the number of cycles or by the sound wave per unit of time. A corresponds to a higher-pitched sound, while frequency corresponds to a lower-pitched sound

3. #83UPSC CDS 2022
   The device used for measuring electric current in a circuit is called
   • AAmmeter
   • BMotor
   • CVoltmeter
   • DGenerator
   Answer: (A) Ammeter
   Explanation

   Option a is the correct ammeter is the device used for measuring in a circuit. It is connected in series within and is designed to measure the flow of through a conductor or a circuit. The based on the principle of electromagnetic the magnetic field generated by the current flow the strength or magnitude of the electric is calibrated to provide direct readings of current in as amperes or milliamperes

4. #84UPSC CDS 2022
   An object is dropped from a height onto the floor, which one of the following remains uniform as it falls?
   • AIts acceleration
   • BIts momentum
   • CIts kinetic energy
   • DIts potential energy
   Answer: (A) Its acceleration
   Explanation

   Option a is the correct acceleration of an object in free fall near the the Earth remains constant. According to the Law of Motion, the net acceleration of the body on mass of an object and force acting on i.e. F/m (where a is acceleration of an object, force acting on the object, and mis mass of the air resistance, all objects near the Earth's the same acceleration due to gravity, which 9.8 meters/ in the downward direction. remains constant throughout the object's fall

5. #85UPSC CDS 2022
   The acceleration due to gravity at the Earth's surface depends on
   • Aits mass only
   • Bits radius only
   • Cboth its mass and radius
   • Deither its mass or its radius
   Answer: (C) both its mass and radius
   Explanation

   Option c is the correct acceleration due to gravity at the Earth's surface by both its mass and radius. This described by the law of universal gravitation, Sir Isaac Newton. According to Newton's law of the force of gravity between two objects is to the product of their masses and to the square of the distance between The formula can be expressed (G is the force of is the gravitational constant 6.673 x 10-11 N 1 and are the masses of the two objects, is the distance between their centers. In the case of the Earth, the acceleration due to gravity (g) force experienced by an object of mass m near the divided by the mass of that the formula for the force of gravity into for acceleration due to gravity, we (G M) is the mass of the Earth, is the radius of the this equation, we can see that the acceleration gravity (g) is influenced by both the mass (M) and (R) of the Earth

6. #86UPSC CSE Prelims 2020
   With the present state of development, Artificial Intelligence can effectively do which of the following? I. Bring down electricity consumption in industrial units 2. Create meaningful short stories and songs 3. Disease diagnosis 4. Text-to-Speech Conversion 5. Wireless transmission of electrical energySelect the correct answer using the code given below
   • A1, 2, 3 and 5 only
   • B1, 3 and 4 only
   • C2, 4 and 5 only
   • D1, 2, 3, 4 and 5
   Answer: (B) 1, 3 and 4 only
   Explanation

   Option b is the correct Intelligence can effectively do the Bring down electricity consumption in industrial units: AI can help optimize energy efficiency and reduce wastage by using smart sensors, predictive analytics, and intelligent control systems. Disease diagnosis: AI can assist doctors and healthcare professionals in diagnosing various diseases and conditions by analyzing medical images, lab tests, symptoms, and patient history. Text-to-Speech Conversion: AI can convert written text into natural-sounding speech by using techniques such as natural language processing, speech synthesis, and deep cannot effectively do the following tasks: Create meaningful shol't stories and songs: Al can generate creative content such as poems, stories, songs, etc., but they may not be meaningful, coherent, or original. AI lacks human emotions, intuition, and cultural context that are essential for

7. #87UPSC CSE Prelims 2019
   In the context of wearable technology, which of the following tasks is/are accomplished by wearable devices? 1. Location identification of a person 2. Sleep monitoring of a person 3. Assisting the hearing-impaired personSelect the correct answer using the code given below
   • A1 only
   • B2 and 3 only
   • C3 only
   • D1, 2 and 3
   Answer: (D) 1, 2 and 3
   Explanation

   Option dis the correct technology includes devices that can tasks such as location identification, and assisting the hearing-impaired examples of wearable devices are: Location identification of a person: Wearable device can determine the geographical position of the person wearing it. This can be done by using GPS (Global Positioning System) or other methods of location tracking. For example, a smartwatch can show the user their current location on a map or give them directions to a destination. Sleep monitoring of a person: Wearable device can measure and analyze the sleep patterns of the person wearing it. This can be done by using sensors that detect the movement, heart rate, brain activity, or other indicators of sleep quality. For example, a wristband can track the user's sleep stages (light, deep, REM) and give them feedback on how to improve their sleep. Assisting the hearing-imp

8. #88UPSC CSE Prelims 2019
   Recently, scientists observed the merger of giant 'black holes' billions of light years away from the Earth. What is the signifkance of this observation?
   • A'Higgs boson particles' were detected
   • B'Gravitational waves' were detected
   • CPossibility of inter-galactic space travel through 'wormhole' was confirmed
   • DIt enabled the scientists to understand 'singularity'
   Answer: (B) 'Gravitational waves' were detected
   Explanation

   Option b is the correct recent observation of the merger of giant black of light-years away from Earth is it enabled the detection of gravitational waves are ripples in spacetime caused acceleration of massive objects, such as the merger of black holes. This discovery existence of gravitational waves, which was achievement in astrophysics. These predicted by Albert Einstein's theory of Gravitational wave astronomy provides a to study the Universe, offering insights into black stars, and other phenomena that were through traditional observational Ii Important Holes: Black holes are formed when massive stars undergo gravitational collapse. After exhausting their nuclear fuel, they can no longer counteract the force of gravity. At the center of a black hole lies a singularity, a point where gravity becomes infinitely strong and spacetime is infinitely curved. The boundary surrounding a blac

9. #89UPSC CSE Prelims 2018
   Consider the following statements: 1. The Earth's magnetic field has reversed every few hundred thousand years. 2. When the Earth was created more than million years ago, there was oxygen and no carbon dioxide. 3. When living organisms originated, they modified the early atmosphere of the Earth.Which of the statements given above is/are correct?
   • A1 only
   • B2 and 3 only
   • C1 and 3 only
   • D1, 2 and 3
   Answer: (C) 1 and 3 only
   Explanation

   infonnation on cyber Option c is the correct answer. Forecast and alerts of cyber security Geomagnetic Reversal is a change in a planet's magnetic Emergency measures for handling cyber such the positions of magnetic north and magnetic south interchanged, while geographic north and geographic Coordination of cyber incident response remain unchanged. Issue guidelines, advisories, vulnerability Earth was created the atmosphere had abundance and whitepapers relating to information sulphide and Carbon dioxide. practices, procedures, prevention, response composition of Earth's early atmosphere was modified reporting of cyber living world through the process of photosynthesis. 74. Solution: (a)

10. #90Previous year
    A recent movie titled 'The Man Who Knew Infinity' is based on the biography of- [UPSC CSE Pre 2016)
    • AS. Ramanujan
    • BS. Chandrashekhar
    • CS. N. Bose
    • DC.V. Raman
    Answer: (A) S. Ramanujan
    Explanation

    Option a is the correct movie "The Man Who Knew Infinity" is based on of Srinivasa Ramanujan. This film, released depicts the life and mathematical contributions legendary Indian mathematician Srinivasa portrays his journey from humble beginnings in India collaboration with British mathematician G.H. Hardy University, highlighting his profound impact field of mathematics. Important Tips Srinivasa Ramanujan: Ramanujan was born in Erode, India, in 1887. He came from a poor family and had little formal education. However, he was a self-taught genius and began making mathematical discoveries at a young age. In 1913, Ramanujan wrote to British mathematician G. H. Hardy, seeking his help in getting his work published. Hardy was impressed by Ramanujan's work and invited him to come to Cambridge. Ramanujan spent the next several years at Cambridge, working with Hardy and other mathematicians. In

11. #91UPSC CSE Prelims 2015
    With reference to 'Near Field Communication (NFC Technolog which of the following statements is/are correct:? 1. It is a contactless communication technology that uses electromagnetic radio fields. 2. NFC is designed for use by devices which can be at a distance of even a metre from each other. 3. NFC can use encryption when sending sensitive information.Select the correct answer using the code given below
    • A1 and 2 only
    • B3 only
    • C1 and 3 only
    • D1, 2 and 3
    Answer: (C) 1 and 3 only
    Explanation

    Option c is the correct l is correct: Near Field Communication a contactless communication technology that radio fields. NFC does not require or wires to transfer data between two devices. uses electromagnetic waves that can travel through the create a wireless 2 is incorrect: NFC can only work over a distance of 4 cm or less. NFC is a short-range that enables communication between two a distance of 4 cm (1.57 in) or 3 is correct: NFC can use encryption sensitive information, such as credit card personal data

12. #92UPSC CSE Prelims 2012
    Electrically charged particles from space travelling at speeds of several hundred km/sec can severely living beings if they reach the surface of the Earth. What prevents them the surface of the Earth?
    • AThe Earth's magnetic field diverts them towards its poles
    • BThe Ozone layer around the Earth reflects them back to outer space
    • CMoisture in the upper layers of atmosphere prevents them from reaching the surface of the Earth
    • DNone of the given above is correct
    Answer: (A) The Earth's magnetic field diverts them towards its poles
    Explanation

    Option a is the correct charged particles from space, such as and cosmic rays, are mostly deflected away surface of the Earth due to the Earth's magnetic magnetic field diverts these charged particles magnetic poles, where they interact with the create phenomena like the auroras. This known as the magnetosphere, plays a crucial role harmful charged particles from directly Earth's surface and potentially harming living beings. Important Tips Earth's magnetosphere: The magnetosphere is the region around a planet that is dominated by the planet's magnetic field l f B Among the rocky planets in our solar system, Earth possesses the strongest magnetosphere. The magnetosphere plays a vital role in shielding our planet from harmful solar and cosmic particle radiation, as well as preventing the erosion of the Earth's atmosphere caused by the solar wind. Earth's magnetosphere is generated by the

13. #93UPSC CSE Prelims 2012
    A team of scientists at Brookhaven National Laboratory including those from India created the heaviest (anti-helium nucleus). What is/are the implication/implkatiorrn of the creation of anti-matter? 1. It will make mineral prospecting and oil exploration easier and cheaper. 2. It will help probe the possibility of the existence of stars and galaxies made of anti-matter. 3. It will help to understand the evolution of the universe.Select the correct answer using the codes given below
    • A1 only
    • B2 and 3 only
    • C3 only
    • D1, 2 and 3
    Answer: (B) 2 and 3 only
    Explanation

    Option b is the correct 1 is incorrect- Antimatter is very difficult to produce. It is also very dangerous, as it matter on contact. As a result, it is unlikely will be widely used in mineral prospecting and in the near future. There are a number of that are used to prospect for minerals and oil, seismic surveys and magnetic surveys. These much more cost-effective than using antimatter, and also 2 is correct- If antimatter exists in the universe, likely to be found in regions that are separate from is because matter and antimatter annihilate each contact. By studying the cosmic ray showers that when antimatter interacts with matter, learn more about the distribution of antimatter in 3 is correct- The early universe is thought to very hot and dense, and it is likely that both antimatter were created in equal amounts. However, today is almost entirely made of matter. trying to understand w

14. #94UPSC CSE Prelims 2012
    Graphene is frequently in news recently. What is its importance? 1. It is a two-dimensional material and has good electrical conductivity. 2. It is one of the thinnest but strongest materials tested so far. 3. It is entirely made of silicon and has high optical transparency. 4. It can be used as 'conducting electrodes' required for touch screens, LCDs and organic LEDs.Which of the statements given above are correct?
    • A1 and 2 only
    • B3 and 4 only
    • C1, 2 and 4 only
    • D1, 2, 3 and 4
    Answer: (C) 1, 2 and 4 only
    Explanation

    Option c is the correct is a one-atom-thick layer of carbon atoms arranged in a hexagonal lattice. It is the Graphite. Graphene is the thinnest compound man at one atom thick, the lightest material known, compound discovered (between 100-300 than the field of optics, transparency is the physical allowing light to pass through the material scattering of has high optical transparency and can light across the visible and near-infrared parts of and thus it is potentially suitabile for use in

15. #95UPSC CSE Prelims 2008
    Which of the following laser ray is used in laser printers?
    • ADye laser
    • BSemiconductor laser
    • CExcimer laser
    • DGas laser
    Answer: (B) Semiconductor laser
    Explanation

    Option bis the correct printers use a laser beam (typically, an arsenide semiconductor laser) that red or infrared light to project an image of the page printed onto an electrically charged drum. are also called diode lasers, and they are widely used applications such as optical communication, laser pointers, and CD/DVD players

16. #96UPSC CSE Prelims 1999
    Low temperatures (cryogenics) find application in
    • ASpace travel, surgery, and magnetic levitation
    • BSurgery, magnetic levitation, and telemetry
    • CSpace travel, surgery, and telemetry
    • DSpace travel, magnetic levitation, and telemetry
    Answer: (D) Space travel, magnetic levitation, and telemetry
    Explanation

    Option d is the correct temperatures, or cryogenics, find application fields, including: Space Travel: Cryogenics are used in rocket propulsion systems. Liquid hydrogen and liquid oxygen, which are cryogenic fluids, are commonly used as rocket propellants due to their high energy density. Magnetic Levitation: Cryogenic superconducting magnets are used in magnetic levitation (maglev) trains and magnetic resonance imaging (MRI) machines. Superconducting materials exhibit zero electrical resistance at low temperatures, enabling strong and efficient magnetic fields. Telemetry: Cryogenic systems are employed in telemetry, especially in space missions. Cryogenic temperatures are used to cool sensors and instruments on spacecraft to improve their performance

17. #97UPPCS 2010
    The concept of expanding universe is based on
    • ADoppler effect
    • BStark effect
    • CZeeman effect
    • DRaman effect
    Answer: (A) Doppler effect
    Explanation

    Option a is the correct concept of an expanding universe is primarily the Doppler effect. The Doppler effect, also known Doppler shift, is a phenomenon in physics that change in frequency or wavelength of a wave (such or sound) in relation to an observer moving the source of the wave. In the context of cosmology, effect is observed in the form of redshift in from distant galaxies. When galaxies are from us, the light they emit is shifted toward the of the electromagnetic spectrum. This redshift is evidence indicating the expansion of and is a cornerstone of the Big Bang theory. Important Tips Doppler Effect: The Doppler effect refers to the apparent change in frequency or wavelength of waves observed by an observer in motion relative to the source of the waves. It was first described by Austrian physicist Christian Doppler in 1842. The effect is commonly observed in both sound and light

18. #98Previous year
    The Magnetic Resonance Imaging (MRI) is based on the phenomenon of - [. (Spl.) (Mains) 2008)
    • ANuclear magnetic resonance
    • BElectron spin resonance
    • CElectron paramagnetic resonance
    • DDiamagnetism of human tissues
    Answer: (A) Nuclear magnetic resonance
    Explanation

    Option a is the correct resonance imaging (MRI) is a medical that uses a strong magnetic field and to create detailed images of the internal the body. MRI scans are used to diagnose a wide medical conditions, including cancer, heart stroke. MRI is based on the phenomenon of resonance (NMR). NMR is a property of nuclei that allows them to absorb radio waves are placed in a strong magnetic field. The amount waves absorbed depends on the type of nucleus and of the magnetic an MRI scan, the patient lies on a table that is a large, donut-shaped machine. The machine strong magnetic field that aligns the hydrogen atoms patient's body. Radio waves are then transmitted patient's body. The hydrogen atoms absorb the and then emit them back out in a different computer uses the radio waves emitted by the to create images of the patient's internal scans can be used to image any part of the body, are p

19. #99UPPCS 1996
    The 'Black Box' of an aeroplane is of
    • AWhite colour
    • BRed colour
    • CBlack colour
    • DOrange colour
    Answer: (D) Orange colour
    Explanation

    Option d is the correct 'Black Box' of an airplane is not actually black in is typically painted bright orange. This color is aid in the device's recovery after accidents. The box" is a misnomer and an outdated name for There are two types of flight recording devices: data recorder (FDR) and the cockpit voice Together, they document an aircraft's flight assist in investigations. These recorders are withstand extreme conditions, including high and high temperatures, to ensure data retrieval event of an resistance of a galvanometer is a property of its coil, which has a moderate value (about 100 ohms). To measure electric resistance, other devices such as ohmmeters or Wheatstone bridges are used. A voltmeter measures the potential difference or voltage between two points in a circuit. An ammeter measures the electric current flowing through a circuit. A potentiometer is a device that can m

20. #100State PCS 2020
    The name of India's first indigenous anti radiation missile is
    • ATandav
    • BTrinetra
    • CSaksham
    • DRudram (e) None of the above/More than one of the above
    Answer: (D) Rudram (e) None of the above/More than one of the above
    Explanation

    Important Option d is the correct answer. X-rays are a form of electromagnetic radiation name of India's first indigenous anti-radiation missile have a wavelength ranging from 0.01 to 10 Rudram. It was successfully launched from a Sukhoi 30 corresponding to frequencies in the range 3 x 10" jet in October 2020. Developed by DRDO, this air-to- Hz to Hz and energies in the range 100 missile is designed to locate and target radiation to 100 They are produced when sources, fulfilling the Indian Air Force's need to electrons collide with metal plates or when its Suppression of Enemy Air Defence (SEAD) emit inner-shell electrons. They are used for imaging, security scanning, astronomy, industry and Important Tips restoration. What is an anti-radiation missile? Alpha particles are helium nuclei that consist of two protons and two neutrons. They are emitted by the Anti-radiation missiles are engi

21. #101CGPSC 2019
    In computers, chip is made up of: n
    • AA thin layer of cobalt
    • BA thin layer of silicon
    • CA thin layer of silver
    • DA thin layer of copper
    Answer: (B) A thin layer of silicon
    Explanation

    Option b is the correct computer chip is a packaged set of electronic onto a thin, circular wafer made of the one of the most abundant elements in the Silicon is a naturally occurring semiconductor, it can conduct electricity under certain act as an insulator under others. By adding silicon, its electrical properties can be changed, a as doping. This allows the creation of are tiny switches that turn an electrical current off. Transistors are the basic building blocks of and millions of them can be packed onto a single materials used in making computer chips or aluminum for the metal wires that connect and silicon dioxide for the insulator that circuits

22. #102JPSC 2021
    Cloud computing services does not include
    • APlatform as a service
    • BSoftware as a service
    • CAllotment of electromagnetic spectrum
    • DInfrastructure as a service
    Answer: (C) Allotment of electromagnetic spectrum
    Explanation

    Option c is the correct of electromagnetic spectrum is not a service. It is the process of assigning bands of the electromagnetic spectrum to different applications, such as radio, TV, mobile phones, communications. It is usually done by a or an international organization. Important Tips Cloud computing services are infrastructure, platforms, or software that are hosted by third-party providers and made available to users through the internet. The main cloud computing service models include: Infrastructure as a service This model offers compute and storage services, such as servers, networks, operating systems, and virtual machines. Platform as a service This model offers a develop-and-deploy environment to build cloud apps, such as web servers, databases, development tools, and middleware. Software as a service This model delivers apps as services, such as email, office suites, CRM, and

23. #103State PCS 2013
    On which principle, a Jet Engine works?
    • AConservation of linear momentum
    • BConservation of angular momentum
    • CConservation of energy
    • DConservation of mass P [ I ]
    Answer: (A) Conservation of linear momentum
    Explanation

    Option a is the correct engines work on the principle of conservation of This principle states that the total a system must remain constant, unless an external on the system. In a jet engine, the momentum of that is taken in at the front of the engine is increased it and mixing it with fuel. The mixture is and the hot gases that are produced are the back of the engine at high speed. This creates force, which is the thrust that propels the Important Tips Conservation of linear momentum in Jet Engine: The conservation of linear momentum can be expressed by the following equation: ml vl (ml where: ml is the mass of the air that is taken in at the front of the engine vl is the velocity of the air that is taken in at the front of the engine is the mass of the fuel that is injected into the engine is the velocity of the fuel that is injected into the engine is the velocity of the hot gases tha

24. #104UPSC CSE Prelims 2021
    Which of the following have species that can establish symbiotic relationship with other organisms? 1. Cnidarians 2. Fungi 3. ProtozoaSelect the correct answer 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 natural settings, lichens and mosses are most likely found surviving on surfaces without Ferns require indirect sunlight, moist soil, and atmosphere for their growth. They prefer potting good drainage and high organic content, so they likely to be found on surfaces without Lichens are a unique life form consisting of partnership between a fungus and an alga. grow on any undisturbed surface, including rocks, wood, soil, and even non-natural surfaces like and plastic. Lichens thrive in clean air and little to grow, making them well-suited for Mosses are non-flowering plants that spores. They have stems and leaves but lack true are adapted to low-light conditions and thrive and moist environments. They can grow on such as rocks, trees, and even rooftops, need for Mushrooms, on the other hand, are the of fungi and typically require a substrate to as decaying organic m

25. #105UPPCS 2015
    Which of the following is NOT correct about the ecosystem?
    • AIt comprises both, abiotic and biotic components
    • BIt has its productivity
    • CIt is a closed system
    • DIt is a natural resource system
    Answer: (C) It is a closed system
    Explanation

    Option c is the correct is an open system. It is a natural system organisms, their physical surroundings, and in a specific space. It encompasses like minerals, climate, soil, water, biotic elements consisting of all living constituents are linked by energy flow and Sunlight serves as the primary energy source utilized by autotrophic organisms, vegetation, for photosynthesis. These sunlight, carbon dioxide, and water into energy rich carbohydrates. This energy supports the production organic compounds, maintaining life processes The autotrophic part of the ecosystem is the producer level

26. #106UPPCS 2015
    Which of the following statements is correct?
    • AThe energy flow in the Biospheric ecosystem is unidirectional
    • BThe energy flow in the Biospheric ecosystem is cyclic
    • CRelative loss of energy in natural ecosystem decreases with increasing trophic levels
    • DSpecies at progressively higher trophic levels appear to be less efficient in using available energy
    Answer: (A) The energy flow in the Biospheric ecosystem is unidirectional
    Explanation

    Option a is the correct energy flow in the biospheric ecosystem is energy is lost as heat at each trophic level and of the energy (Lindeman's Law) is transferred to tropic level. This is because organisms must use some energy they consume to maintain their own life as respiration and movement. The remaining energy passed on to the next trophic level

27. #107UPPCS 2011
    Which one of the following sources of renewable energy has the greatest potential in India?
    • ASolar power
    • BBiomass power
    • CSmall hydel power
    • DEnergy recovery from waste
    Answer: (A) Solar power
    Explanation

    Option a is correct pyramid of energy maintains its upright structure be inverted due to the constant loss of energy as each step when energy moves from one trophic level to Each segment within the energy pyramid quantity of energy existing at each trophic level specific timeframe or on an annual basis per unit of Important Tips A lotic habitat is a freshwater ecosystem that has flowing water. Rivers, streams, and brooks are all examples oflotic habitats. Lotic habitats are typically deeper and narrower than lentic habitats, and they have a faster current. Lotic habitats are home to a wide variety of plants and animals, including fish, amphibians, reptiles, insects, and birds. Some of the most common plants in lotic habitats include algae, mosses, and liverworts. Some of the most common animals in lotic habitats include trout, salmon, crayfish, and insects such as stoneflies and mayflies

28. #108UPSC CSE Prelims 2023
    Which of the following organisms perform waggle dance for others of their kin to indicate the direction and the distance to a source of their food?
    • AButterflies
    • BDragonflies
    • CHoneybees
    • DWasps
    Answer: (C) Honeybees
    Explanation

    Option c is the correct answer. There are 2 types of dances performed by bees: The Round Dance and The Tail-wagging or Waggle Dance For food sources 25 to 100 metres from the hive or close the round dance is used. The round dance provides no directional cues. The waggle dance takes the place of the round dance as the distance to the food source increases. The waggle dance tells the direction and amount of energy needed to reach the food l f The amount of energy spent (or distance) is represented by the time required to complete one circuit. For a food source which is 200 metres away, a bee might dance 8-9 circuits in 15 seconds, 4-5 in 15 seconds for a source that is 1000 metres away, and 3 circuits in 15 seconds for a source that is 2000 metres away

29. #109UPSC CSE Prelims 2022
    The "Miyawaki method" is well known for the
    • APromotion of commercial farming in arid and semi-arid areas
    • BDevelopment of gardens Using genetically modified flora
    • CCreation of mini forests in urban areas
    • DHarvesting wind energy on coastal areas and on sea surfaces
    Answer: (C) Creation of mini forests in urban areas
    Explanation

    Option c is the correct Municipal Corporation (BMC) has been Miyawaki method to create tiny urban forests in areas of Mumbai. Miyawaki is an based on the work of Japanese botanist in the ENVIRO Process of Miyawaki Method: Initially, native trees of the region are identified and divided into four layers shrub, sub-tree, tree, and canopy. After that, the quality of soil is analyzed and biomass is mixed with it. Biomass mixing help to enhance the perforation capacity, water retention capacity, and nutrients. A mound is built with the soil and the seeds are planted a a very high density. Furthermore, the ground is covered with a thick layer of mulch. Multi-layered saplings are planted close to each other. This blocks sunlight from reaching the ground and prevents weeds from growing. It also keeps the soil moist. The close cropping also ensures that the plants receive sunlight only from the t

30. #110UPPCS 2002
    The amrn.al production of biomass is minimal in which of the following environments?
    • ADeep sea
    • BPrairie
    • CDeciduous forest
    • DTaiga
    Answer: (A) Deep sea
    Explanation

    Option a is the correct annual production of biomass is minimal in the because of the lack of sunlight. Sunlight is photosynthesis, which is the process by which biomass. Without sunlight, plants cannot grow biomass

31. #111State PCS 2008
    One horned rhinoceros is found in the following States
    • AArunachal Pradesh and Tripura
    • BWest Bengal and Assam
    • CArunachal Pradesh and Assam
    • DWest Bengal and Tripura
    Answer: (B) West Bengal and Assam
    Explanation

    environment are referred to as nekton. Nekton includes organisms that actively swim or move in the water Option b is the correct answer. such as fish, turtles, whales, dolphins, and squid. greater one-horned rhinoceros or the Indian rhinoceros organisms are capable of independent movement and native to the Indian subcontinent and is found in riverine not passively carried by currents like and adjacent woodland in northern India Nepal. The species is currently restricted to small Important in the Indo-Nepal Terai, northern parts of West Plankton are microscopic or small floating and Assam. It is also found in cultivated areas and that drift with the current. They are divided as well as modified woodlands in the Terai Arc two main groups: phytoplankton and of India and Nepal and the grasslands of Assam Phytoplankton are plant-like organisms, north Bengal. zooplankton are animal-like organi

32. #112Practice set
    A coin is placed on a card over a tumbler. When the card is rapidly flicked with the finger, the coin placed over it falls in the tumbler. Which of the following laws in physics best describes the concept behind the above phenomenon?
    • ALaw of conservation of Energy
    • BLaw of Inertia
    • CLaw of conservation of momentum
    • DLaw of Friction
    Answer: (B) Law of Inertia
    Explanation

    Option bis the correct first law of motion (the law of inertia) things cannot start, stop, or change direction all and it requires some force from the outside such a change. This property of massive bodies changes in their state of motion is called coin, placed on a card, drop into the tumbler when is rapidly flicked with a finger due to inertia of rest coin. When the card was at rest on the tumbler, the also at rest. When the card is flicked, a momentary on the card, so it moves away. But the coin due to its inertia of rest and falls down into due to the pull of gravity. Important Tips The law of conservation of energy states that energy can neither be created nor be destroyed. Although, it may be transformed from one form to another. If you take all forms of energy into account, the total energy of an isolated system always remains The principle of conservation of momentum states that

33. #113Practice set
    With reference to 'Colloidal Solutions', consider the following statements: 1. It is a type of mixture in which one substance is fully dissolved in another. 6. 2. The scattering of a light beam by the particles of a colloidal solution is called Tyndall effect. 3. The particles of a Colloidal Solution do not settle down at the bottom of the container.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 I is incorrect: A colloidal solution is a mixture in which one substance is dispersed another substance. The dispersed the dispersed phase, is not fully dissolved and can with the naked 2 is correct: The Tyndall effect, named after scientist John Tyndall, is a phenomenon when light scatters through a colloidal light is scattered as it passes through the the dispersed particles to become visible. This is solutions often appear cloudy or 3 is correct: Particles of a Colloidal always in a state of motion and never settle down bottom of a container. A colloid is a mixture that ranging between 1 and 1000 nanometers in are still able to remain evenly distributed solution. These are also known as colloidal the substances remain dispersed and do not settle bottom of the container

34. #114Practice set
    Consider the following statements: 1. Boiling is the 'surface phenomenon' involving change of liquid state to vapour state. 2. The boiling point of a liquid is the temperature at which the vapor pressure of the liquid is less than atmospheric pressure. 3. Evaporation is a 'bulk phenomenon' which involves transition of the liquid particles into gaseous particles.How many of the statements given above are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone In
    Answer: (D) None In
    Explanation

    Option d is the correct 1 is incorrect: The temperature at which a boiling at the atmospheric pressure is known as point. Boiling is a bulk phenomenon (not Particles from the bulk (not only from of the liquid gain enough energy to change into 2 is incorrect: The boiling point of a liquid temperature at which the vapor pressure of the the atmospheric pressure. The vapor pressure is exerted by the molecules of a substance in the in equilibrium with the molecules in the liquid the temperature of a liquid increases, the kinetic its molecules also increases, and more of the enough energy to escape the surface of the liquid a the vapor pressure of a liquid equals the the liquid starts to boil. At this point, bubbles form within the liquid and rise to the Statement 3 is incorrect: Evaporation is a form of vaporisation that happens on the surface of liquids (not a bulk phenomenon) and it involve

35. #115Practice set
    When you cover the surface of the torch with your palm and turn on the torch light in a dark place, you observe light at the other side of your palm, but not clearly. Which of the following properties of your palm is a reason for this phenomenon?
    • ATransparency of palm
    • BOpaqueness of palm
    • CTranslucency of palm
    • DReflection of light by palm
    Answer: (C) Translucency of palm
    Explanation

    Option c is the correct materials allow light to pass through it clearly. The palm is translucent; this is why we can light at the other side of our palm. Important Tips Transparency is the physical property of allowing light to pass through the material clearly. If the palm is transparent, we can see the light clearly at the other side of our palm. Glass, water, air and some plastics are examples of transparent materials An Opaque object completely bans the light from passing through it. It is neither transparent (allowing all light to pass through) nor translucent (allowing some light to pass through). These materials are called opaque. Reflection is when light bounces off an object. The object exhibiting reflective properties will send back the light striking its surface

36. #116Practice set
    With reference to kinetic energy, consider the following statements: 1. It can be transferred between objects. 15. 2. Hot Springs stores kinetic energy in the form of Thermal energy. 3. It is a vector quantity having both magnitude and direction. Ellf H,ow many of the statements given above are correct? Sun. the stars. With respect to the Friction, consider the following statements
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (B) Only two
    Explanation

    Option b is the correct energy is the energy an object has because of 1 is correct: The Kinetic energy of a can be transferred between objects and other kinds of energy. The best example is working Electric power project, where the kinetic energy water is transferred through movement of and then transformed into electric Practi 2 is correct: Thermal energy, known as is a type of kinetic energy. It is generated due motion of atoms when they collide with each other. spring is example of thermal energy where heat due to the quick motion of atoms and when they collide with each 3 is incorrect: Kinetic energy is a scalar it has only magnitude but no direction. The of kinetic energy is joule

37. #117Practice set
    With reference to Newton's laws consider the following pairs: 1. Newton's first Weightlifter struggling law to stand straight with the increasing amount of weight. 2. Newton's The impact of moving second law truck on walls is bigger than that of cycle moving at the same speed. 3. Newton's third The initial jerk we get law when bus suddenly starts/ stops.How many pairs given above are correctly matched?
    • ANone
    • BOnly one
    • COnly two
    • DAll three
    Answer: (B) Only one
    Explanation

    Option b is the correct laws of motion are three basic laws that relationship between the motion of an object and acting on 1 is incorrect; Some weightlifter struggling to with increasing load of weight was explained third law. The first law of motion is also the law of inertia. It states that a body at rest or will continue to be at rest or uniform motion unless a net external force acts on it. Thus, our to resist the change makes it move back bus starts suddenly and go forward while the bus 2 is correct: The Second law of motion states that acting on the body is equal to the product of its acceleration i.e., where f is force, m is mass and acceleration. The impact produced by the objects their mass and velocity (acceleration). Given the the damage caused by the truck is bigger than because of the higher mass of the 3 is incorrect: The initial jerk we get when the starts/stops is becaus

38. #118Practice set
    With reference to astronomical phenomena, consider the following: 1. The share of Dark energy in the total universe is greater than that of Dark matter. 2. While dark matter slows down the expansion of the universe, dark energy speeds it up. 3. While dark matter interacts with light, dark energy does not interact with light.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 correct: Only of the entire universe and the rest of consists of dark dark energy. Dark energy accounts for around total universe, while dark matter accounts for total universe by volume. Thus, it is true that the dark energy in the total universe is greater than that 2 is correct: It is true that dark matter slows expansion of the universe, while dark energy speeds Dark matter works like an attractive force - a kind cement that holds our universe together. In energy is a repulsive force - a sort of anti-gravity drives the universe's ever-accelerating 3 is incorrect: Both dark not interact with the electromagnetic force, that it does not absorb, reflect or emit light, extremely hard to detect

39. #119Practice set
    With reference to Food irradiation, consider the following statements: 1. It is the process of ionising food using rays emanating from radioactive material. 2. Irradiated foods can be stored for years without refrigeration. 3. Early ripening of fruits is one of the applications of food irradiation.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 irradiation is the application of ionising radiation to improve the safety and extend the s.helf life of reducing or eliminating microorganisms and does not make foods radioactive, quality, or noticeably change the taste, appearance of 1 is correct: It is true that food irradiation process of foods with either Gamma rays 2 is correct: Irradiation can be used foods, which can then be stored for years 3 is incorrect: Irradiation of fruits. Thus irradiation is used to delay fruit to increase longevity, not to fasten the process Important Tips Other applications of food irradiation are as follows; Prevention of Foodborne Illness by effectively eliminating organisms that cause foodborne illness, such as Salmonella and Escherichia coli (E. coli). Preservation of foods by destroying or inactivating organisms that cause spoilage and decomposition and extend the shelf life

40. #120Practice set
    Which of the following fields can have potential application of LASER technology? 1. Military operations 2. Medicine 3. Communication 4. Art and Entertainment 5. General-purpose illuminationSelect the correct answer using the code given below
    • A1, 2, 3 and 4 only
    • B1, 3, 4 and 5 only
    • C2, 3, 4 and 5 only
    • D1, 2, 3, 4 and 5
    Answer: (D) 1, 2, 3, 4 and 5
    Explanation

    Option d is the correct potential appliq,tions of LASER technology are varied. While it is well-known that LASERs have in military operations, medicine, and have also found their way into the realm of art and and are used in light shows, CD and and special effects in 1 is correct: The probability of intercepting a is very low due to its narrow beam divergence optical beam, making the laser a suitable secure military tactical 2 is correct Lasers were first used for in 1961 for treatment of skin detached retinas. Presently lasers are being widely numerous medical applications. These include dermatology, angioplasty, cancer cosmetic applications such as laser hair removal and liposuction 3 is correct: Laser light is used in communications to send information over with low loss. Laser light is used in networks. Also, lasers are used in radars and 4 is correct: Lasers are typically bright, bo

More Science & Environment topics