What is General Science One Liners?

General Science One Liners are direct question-and-answer notes covering Physics, Chemistry, and Biology designed for quick and efficient revision.

Are these General Science questions useful for Railway RRB and SSC?

Yes! These one-liners are specifically based on the previous year question papers (PYQs) of Railway RRB Group D, NTPC, ALP, and SSC CGL/CHSL exams.

General Science One Liners 2026-27 | Physics, Chemistry, Biology

Everyday Science one liner - Physics

1. Units and Measurements

What are the base units in the International System of Units (SI) called? - Fundamental Units
How many fundamental units are defined in the modern SI system? - 7
How many supplementary units exist in the SI system (plane angle and solid angle)? - 2
What is the SI unit of luminous intensity? - Candela (cd)
What is the SI unit of amount of substance? - Mole (mol)
What is the SI base unit of thermodynamic temperature? - Kelvin (K)
Which practical unit of astronomical distance represents the distance traveled by light in a vacuum in one year? - Light-year
Approximately how many meters are in one light-year? - $9.46 \times 10^{15}$ meters
What is the largest practical astronomical unit of distance, equal to about 3.26 light-years? - Parsec
What is the mean distance between the center of the Earth and the Sun called? - Astronomical Unit (AU)
Which unit of length equals $10^{-10}$ meters and is used to measure wavelengths of light? - Angstrom (Å)
Which unit equals $10^{-15}$ meters and is used to express nuclear dimensions? - Fermi (Femtometer)
What unit of distance used in maritime and air navigation equals 1,852 meters? - Nautical Mile
In which unit is the navigational speed of ships and sea vessels measured? - Knot
What is the SI unit of force? - Newton (N)
What is the CGS unit of force? - Dyne
How many dynes make up one Newton? - $10^5$ dynes
What is the SI unit of work and energy? - Joule (J)
What is the CGS unit of work and energy? - Erg
How many ergs are equal to one Joule? - $10^7$ ergs
What is the SI unit of power? - Watt (W)
One horsepower (hp) is equal to how many Watts? - 746 Watts
What is the SI unit of frequency? - Hertz (Hz)
What is the SI unit of electric charge? - Coulomb (C)
What is the SI unit of electric potential difference (voltage)? - Volt (V)
What is the SI unit of electrical resistance? - Ohm ($\Omega$)
What is the SI unit of electrical conductance? - Siemens (S)
What is the SI unit of magnetic flux? - Weber (Wb)
What is the SI unit of magnetic flux density (magnetic field)? - Tesla (T)
What is the CGS unit of magnetic field strength? - Gauss (G)
What is the SI unit of electrical inductance? - Henry (H)
What is the SI unit of electrical capacitance? - Farad (F)
What is the SI unit of pressure? - Pascal (Pa)
One bar of atmospheric pressure is equal to how many Pascals? - $10^5$ Pascals
One Torr of pressure is equal to the pressure exerted by how many millimeters of mercury column? - 1 mm of Hg
What is the SI unit of radioactivity? - Becquerel (Bq)
In which unit is the optical power of a corrective lens measured? - Diopter (D)
Which logarithmic unit is used to measure sound intensity levels? - Decibel (dB)
One micron ($\mu$m) is equal to how many meters? - $10^{-6}$ meters
One nanometer (nm) is equal to how many meters? - $10^{-9}$ meters
Which unit equal to $10^{-28}\text{ m}^2$ is used in nuclear physics to measure the cross-sectional area of nuclei? - Barn
Which instrument is used to measure atmospheric pressure? - Barometer
Which instrument is used in aircraft to measure altitude above sea level? - Altimeter
Which instrument is connected in series to measure electric current in a circuit? - Ammeter
Which instrument is connected in parallel to measure electric potential difference? - Voltmeter
Which instrument is used to detect and indicate the direction of small electric currents? - Galvanometer
Which instrument is used to measure the relative density and purity of milk? - Lactometer
Which instrument is used to measure the humidity or moisture content of air? - Hygrometer
Which instrument is used to measure wind speed? - Anemometer
Which instrument is used to measure very high temperatures without physical contact? - Pyrometer

2. Motion, Force, and Laws of Motion

Which quantity represents the shortest straight-line distance between initial and final points? - Displacement
What is the time rate of change of displacement called? - Velocity
What is the time rate of change of velocity called? - Acceleration
Which law states that an object remains at rest or in uniform motion unless acted upon by an external unbalanced force? - Newton's First Law of Motion
Which physical property describes an object's resistance to any change in its state of rest or motion? - Inertia
What fundamental quantity determines the amount of inertia an object possesses? - Mass
Why do passengers fall backward when a stationary bus suddenly starts moving? - Inertia of Rest
Why do passengers lean forward when a moving bus suddenly stops? - Inertia of Motion
Why does dust separate from a carpet when it is beaten with a stick? - Inertia of Rest
Why does mud fly off tangentially from rotating vehicle tires? - Inertia of Direction
What is the product of an object's mass and its velocity called? - Linear Momentum
Which law states that the rate of change of momentum is directly proportional to the applied force ($F = ma$)? - Newton's Second Law of Motion
What is the product of a large force and the short time interval over which it acts called? - Impulse
Why does a cricket fielder pull his hands backward while catching a fast-moving ball? - To increase impact time and reduce impulsive force
Why are shock absorbers fitted in motor vehicles? - To increase impact time and reduce force during bumps
Which law states that for every action, there is an equal and opposite reaction? - Newton's Third Law of Motion
What causes a gun to recoil backward when a bullet is fired forward? - Newton's Third Law of Motion (Reaction Force)
On which law of motion and conservation principle does rocket propulsion primarily operate? - Law of Conservation of Linear Momentum
What contact force always opposes relative motion between two surfaces in contact? - Friction
What is the maximum value of static friction just before an object starts sliding called? - Limiting Friction
Which type of friction is significantly lower than sliding friction and utilized in ball bearings? - Rolling Friction
Why do automobile tires have grooved treads on their surfaces? - To increase friction and prevent skidding
What substances are applied to machine parts to reduce frictional wear and heat? - Lubricants
What is the center-seeking force required to keep an object moving in a circular path called? - Centripetal Force
Why are curved railway tracks and roads banked with an elevated outer edge? - To provide necessary centripetal force
What outward pseudo-force is experienced by an object in a rotating frame of reference? - Centrifugal Force
On which physical force principle does a milk cream separator and spin dryer operate? - Centrifugal Force
What geometric shape does the path of an airborne projectile follow under gravity alone? - Parabola
At what launch angle does a projectile achieve its maximum horizontal range (ignoring air resistance)? - 45 degrees
What is the vertical component of velocity at the highest point of a projectile's flight? - Zero
Why do heavy and light objects dropped simultaneously in a vacuum hit the ground together? - Acceleration due to gravity is independent of mass
Why is it difficult to walk on smooth, frictionless ice? - Lack of sufficient frictional force to push backward
Why are airplanes and bullet trains given streamlined shapes? - To reduce fluid friction (air drag)
What is the maximum constant falling velocity attained when air resistance balances gravity? - Terminal Velocity
Why do falling raindrops reach a steady terminal speed instead of continuously accelerating? - Viscous drag of the atmosphere
What is the mathematical formula for the momentum ($p$) of an object? - $p = mv$
What remains constant in an isolated system with no external forces acting on it? - Total Linear Momentum
What is the force exerted on an object moving in a circle of radius $r$ at velocity $v$? - Centripetal Force ($F = \frac{mv^2}{r}$)
In uniform circular motion, which property changes continuously while speed remains constant? - Direction of Velocity
What type of motion involves constant speed along a circular track with non-zero acceleration? - Uniform Circular Motion
What happens to a passenger sitting inside a car when it takes a sharp left turn? - Leans outward to the right due to inertia
What is the SI unit of momentum? - kg·m/s
What is the SI unit of impulse? - N·s (or kg·m/s)
What happens to an object when the net unbalanced force acting on it is zero? - It maintains constant velocity (or rest)
What kind of physical quantity is force (scalar or vector)? - Vector Quantity
What kind of physical quantity is momentum? - Vector Quantity
What happens to the stopping distance of a car if its speed is doubled (under uniform braking)? - It increases fourfold
What term describes a frame of reference in which Newton's first law does not hold without fictitious forces? - Non-Inertial Reference Frame
What is the reaction force when a swimmer pushes water backward? - Water pushes the swimmer forward
Why does a stepping passenger push a small rowboat backward away from the riverbank? - Equal and opposite reaction force

3. Work, Energy, and Power

In physics, what is work done when the applied force and displacement are perpendicular ($\theta = 90^\circ$)? - Zero
Why is the work done against gravity by a porter carrying a load on his head on a flat road zero? - Force and displacement are perpendicular ($\cos 90^\circ = 0$)
What is the work done by centripetal force on an object in a circular orbit? - Zero
What type of work is done by the force of friction against a sliding box? - Negative Work
What is the energy possessed by an object due to its motion called? - Kinetic Energy
What is the mathematical formula for Kinetic Energy? - $\text{KE} = \frac{1}{2}mv^2$
By what factor does the kinetic energy of an object increase if its speed is doubled? - 4 times
By what factor does kinetic energy change if the momentum of a body is doubled? - Increases 4 times ($\text{KE} = \frac{p^2}{2m}$)
What is the energy possessed by an object due to its position, elevation, or configuration called? - Potential Energy
What is the gravitational potential energy of an object of mass $m$ at height $h$? - $mgh$
What type of energy is stored in a stretched bow or a compressed mechanical spring? - Elastic Potential Energy
What form of energy is possessed by water stored behind a high hydroelectric dam? - Gravitational Potential Energy
Which theorem states that net work done on an object equals the change in its kinetic energy? - Work-Energy Theorem
Which fundamental law states that energy can neither be created nor destroyed, only transformed? - Law of Conservation of Energy
What happens to the sum of potential and kinetic energy of an object falling freely under gravity in a vacuum? - Remains Constant
What is the potential energy of a simple pendulum at its maximum displacement (extreme position)? - Maximum
What is the kinetic energy of a simple pendulum at its lowest (mean) position? - Maximum
Which device converts sound energy directly into electrical energy? - Microphone
Which device converts electrical energy into sound energy? - Loudspeaker
Which device converts electrical energy into mechanical energy? - Electric Motor
Which device converts mechanical energy into electrical energy using electromagnetic induction? - Electric Generator (Dynamo)
Which device converts incident light energy directly into electrical energy? - Solar Cell (Photovoltaic Cell)
Which device transforms stored chemical energy into electrical energy? - Electric Cell (Battery)
What energy conversion takes place during photosynthesis in green plants? - Light Energy into Chemical Energy
What is the rate of doing work or consuming energy called? - Power
What is the SI unit of power? - Watt (W)
How many Joules are equivalent to one kilowatt-hour (1 kWh)? - $3.6 \times 10^6$ Joules ($3.6\text{ MJ}$)
What is one kilowatt-hour (1 kWh) of electricity commercially called? - 1 Board of Trade (BOT) Unit
Energy sources that replenish naturally on human timescales are called what? - Renewable Energy Sources
Which fossil fuel sources deplete upon extraction and cannot be quickly replenished? - Non-Renewable Energy Sources
Which renewable energy technology converts moving air currents into rotational power? - Wind Turbine
What is the primary combustible gas present in Biogas? - Methane ($\text{CH}_4$)
Which type of energy harnesses natural thermal heat from within the Earth's crust? - Geothermal Energy
Which power system exploits the temperature difference between warm ocean surface water and cold deep water? - Ocean Thermal Energy Conversion (OTEC)
What form of energy utilizes the gravitational pull of the Moon and Sun on sea levels? - Tidal Energy
What process powers nuclear energy in commercial atomic power plants? - Nuclear Fission
What process generates the light and heat energy produced inside the core of the Sun? - Nuclear Fusion
Which famous equation by Albert Einstein demonstrates mass-energy equivalence? - $E = mc^2$
What is the ratio of Load to Effort in a simple machine called? - Mechanical Advantage (MA)
What is the ratio of distance moved by effort to distance moved by load in a machine? - Velocity Ratio (VR)
What is the relationship between Mechanical Advantage, Velocity Ratio, and Efficiency ($\eta$)? - $\eta = \frac{\text{MA}}{\text{VR}}$
Why can no real machine have an efficiency equal to or greater than 100%? - Energy losses due to friction and heat
What is the power of a machine that does 1 Joule of work in 1 second? - 1 Watt
What type of energy is stored in fossil fuels like coal and petroleum? - Chemical Energy
In an electric iron or toaster, into what form is electrical energy converted? - Heat Energy
What energy transformation occurs in a steam engine? - Heat Energy into Mechanical Energy
What is the work done when a force moves an object in the exact direction of the force? - Positive Work
What is the scalar product of force and displacement vectors equal to? - Work Done
In which unit is human dietary metabolic energy intake commonly expressed? - Calorie (or Kilocalorie)
One dietary kilocalorie (kcal) equals approximately how many Joules? - 4,184 Joules

4. Gravitation and Pressure

Who formulated the Universal Law of Gravitation? - Sir Isaac Newton
What is the value of the Universal Gravitational Constant ($G$)? - $6.674 \times 10^{-11}\text{ N}\cdot\text{m}^2/\text{kg}^2$
Who first experimentally measured the value of $G$ using a torsion balance in 1798? - Henry Cavendish
What is the standard average acceleration due to gravity ($g$) at sea level on Earth? - $9.8\text{ m/s}^2$
Where on the Earth's surface is the value of acceleration due to gravity ($g$) maximum? - At the Poles
Where on the Earth's surface is the value of acceleration due to gravity ($g$) minimum? - At the Equator
What happens to the value of $g$ as an object is taken higher above the Earth's surface? - It Decreases
What happens to the value of $g$ as one moves deeper below the Earth's surface? - It Decreases
What is the value of acceleration due to gravity at the exact center of the Earth? - Zero ($g = 0$)
What would happen to the value of $g$ at the equator if the Earth stopped rotating? - It would Increase
What is the measure of the quantity of matter contained in a body called? - Mass
What is the downward gravitational force acting on a body called ($W = mg$)? - Weight
What is the ratio of acceleration due to gravity on the Moon compared to that on Earth? - Approximately 1/6th
If a person's mass is 60 kg on Earth, what will be their mass on the surface of the Moon? - 60 kg
What is the apparent weight of an astronaut inside an unpowered orbiting spacecraft? - Zero (Weightlessness)
What happens to the apparent weight of a person in an elevator accelerating upward? - It Increases ($R = m(g+a)$)
What happens to the apparent weight of a person in an elevator accelerating downward? - It Decreases ($R = m(g-a)$)
What is the apparent weight of a person in an elevator whose cables snap (free fall)? - Zero
What is the minimum velocity needed for an object to permanently escape Earth's gravity? - Escape Velocity
What is the escape velocity from the surface of the Earth? - $11.2\text{ km/s}$
Why does the Moon lack a permanent atmosphere? - Low escape velocity ($2.38\text{ km/s}$) compared to thermal gas speeds
At what approximate altitude above Earth's equator do geostationary satellites orbit? - $35,786\text{ km}$
What is the orbital period of a geostationary satellite? - 24 hours (West to East)
What is thrust force acting perpendicularly per unit area called? - Pressure ($P = \frac{F}{A}$)
What is the SI unit of pressure? - Pascal (Pa)
Why do cutting knives and needles have sharp, pointed edges? - To reduce area and maximize cutting pressure
Why are wide continuous tracks used on heavy army battle tanks and bulldozers? - To increase surface area and reduce pressure on the ground
Why are the shoulder straps of school bags made wide? - To reduce pressure on the shoulders
What is standard atmospheric pressure at mean sea level in millimeters of mercury? - 760 mm of Hg
What happens to atmospheric pressure as altitude increases into the mountains? - It Decreases
Why does water boil at a temperature below $100^\circ\text{C}$ on high mountain tops? - Decreased atmospheric pressure lowers the boiling point
Why does a pressure cooker cook food significantly faster? - Higher internal pressure raises the boiling point of water
Why do fountain pens often leak ink in high-altitude airplane cabins? - Internal ink pressure exceeds reduced cabin air pressure
What does a sudden, sharp drop in a barometer's mercury column indicate? - Approaching Storm or Cyclone
What does a gradual, steady decrease in barometric reading indicate? - Likelihood of Rain
What does a gradual, steady rise in barometric reading indicate? - Fair and Clear Weather
What is the formula for hydrostatic fluid pressure at depth $h$ in a liquid of density $\rho$? - $P = h\rho g$
Why are the base walls of water reservoir dams built much thicker than the top? - Liquid pressure increases with depth
Which law states that pressure applied to an enclosed fluid is transmitted equally in all directions? - Pascal’s Law
On which physical law do hydraulic brakes, hydraulic jacks, and hydraulic presses operate? - Pascal’s Law
Which principle states that an immersed body experiences an upward buoyant force equal to the weight of fluid displaced? - Archimedes’ Principle
What is the upward force exerted by a fluid on an immersed body called? - Buoyant Force (Upthrust)
Why does a heavy iron ship float on water while a small solid iron ball sinks? - Ship's hollow hull displaces a volume of water equal to its total weight
Why does an iron nail sink in water but float on liquid mercury? - Density of mercury is greater than the density of iron
What fraction of an iceberg's volume remains submerged below the surface of seawater? - Approximately 9/10th
What happens to the water level in a glass when a floating ice cube melts completely? - Remains Unchanged
Why is it easier for a person to swim in seawater than in fresh river water? - Higher saline water density provides greater buoyant upthrust

5. Optics (Light)

What type of wave is light classified as? - Electromagnetic Transverse Wave
What is the speed of light in a vacuum? - $3 \times 10^8\text{ m/s}$ ($300,000\text{ km/s}$)
Approximately how long does sunlight take to travel to the Earth's surface? - 8 minutes 20 seconds (500 seconds)
How long does light reflected from the Moon take to reach the Earth? - Approximately 1.28 seconds
What type of image is always formed by a flat plane mirror? - Virtual, Erect, and Same Size (Laterally Inverted)
What minimum vertical mirror height is needed for a person to view their complete image? - Half of the person's height
How many images are formed when an object is placed between two parallel plane mirrors? - Infinite
Which optical instrument uses multiple reflections inside a tube to create symmetrical patterns? - Kaleidoscope
Which type of spherical mirror is used as a shaving and dental examination mirror? - Concave Mirror
Which type of mirror is used in automobile headlights and searchlight reflectors? - Concave Mirror
Which type of mirror is used as a driver's rear-view side mirror in motor vehicles? - Convex Mirror
Why are convex mirrors preferred as vehicle rear-view mirrors? - They provide an erect, diminished image with a wide field of view
What optical phenomenon describes the bending of light as it passes from one medium to another? - Refraction of Light
When a ray of light enters an optically denser medium from a rarer medium, how does it bend? - Towards the Normal
When a ray of light enters a rarer medium from a denser medium, how does it bend? - Away from the Normal
Which law relates the angle of incidence to the angle of refraction ($\frac{\sin i}{\sin r} = \mu$)? - Snell’s Law
Why does a straight coin at the bottom of a water container appear slightly raised? - Refraction of Light
Why does a straight pencil partially immersed in water appear bent at the surface? - Refraction of Light
What optical phenomenon causes the twinkling of stars at night? - Atmospheric Refraction of Starlight
Why does the Sun appear visible slightly before sunrise and after sunset? - Atmospheric Refraction
What is the angle of incidence called when the corresponding angle of refraction in the rarer medium is $90^\circ$? - Critical Angle
What optical phenomenon occurs when light in a denser medium strikes a boundary beyond the critical angle? - Total Internal Reflection (TIR)
Which optical principle causes the intense sparkling brilliance of a cut diamond? - Total Internal Reflection
What optical illusion in hot deserts makes distant wet pools appear on hot ground? - Mirage (caused by TIR)
On which optical principle do telecommunication optical fibers transmit light signals? - Total Internal Reflection
Which medical instrument uses optical fiber bundles to view inside human internal organs? - Endoscope
What is the separation of white light into its constituent colors by a glass prism called? - Dispersion of Light
Who first demonstrated that white sunlight is composed of seven constituent colors using a prism? - Sir Isaac Newton
Which visible spectral color undergoes the maximum bending (deviation) in a prism? - Violet
Which visible spectral color undergoes the minimum bending (deviation) in a prism? - Red
Which color in the visible spectrum has the longest wavelength and lowest frequency? - Red
Which color in the visible spectrum has the shortest wavelength and highest frequency? - Violet
What natural phenomenon involves dispersion, refraction, and internal reflection in raindrops? - Rainbow
Which law states that light scattering intensity is inversely proportional to $\lambda^4$? - Rayleigh’s Scattering Law
Why does the clear daytime sky appear blue? - Preferential scattering of shorter blue wavelengths by air molecules
Why does the Sun appear reddish during sunrise and sunset? - Longer red wavelengths scatter least through the thick atmosphere
What color does the sky appear to an astronaut in outer space or on the Moon? - Black (Dark)
Why is red color used universally for danger signals and traffic stoplights? - It has the longest wavelength and scatters least in fog and dust
What vision defect prevents clear focusing on distant objects (nearsightedness)? - Myopia
Where is the image formed in an uncorrected myopic eye for distant objects? - In front of the Retina
Which type of lens is prescribed to correct Myopia? - Concave (Diverging) Lens
What vision defect prevents clear focusing on nearby objects (farsightedness)? - Hypermetropia
Where is the image formed in an uncorrected hypermetropic eye for nearby objects? - Behind the Retina
Which type of lens is prescribed to correct Hypermetropia? - Convex (Converging) Lens
Which age-related defect of vision reduces the eye's power of accommodation? - Presbyopia
What type of lens is used to correct Presbyopia? - Bifocal Lens
Which vision defect caused by irregular corneal curvature is corrected by cylindrical lenses? - Astigmatism
On which light-sensitive screen at the back of the human eye are images formed? - Retina
What type of image is naturally formed on the human retina? - Real and Inverted
What is the least distance of distinct vision (near point) for a normal healthy human eye? - 25 cm

6. Sound and Waves

What type of wave is sound classified as in air and gases? - Longitudinal Mechanical Wave
Why can sound waves not travel through outer space or a vacuum? - Sound requires a material medium to propagate
What alternating regions of high and low density make up a longitudinal sound wave? - Compressions and Rarefactions
In which state of matter does sound travel with the highest velocity? - Solids
In which state of matter does sound travel with the slowest velocity? - Gases
What is the speed of sound in dry air at $0^\circ\text{C}$? - Approximately $331\text{ m/s}$
What is the speed of sound in air at normal room temperature ($20^\circ\text{C}$)? - Approximately $343\text{ m/s}$
By how much does the speed of sound in air increase per $1^\circ\text{C}$ rise in temperature? - $0.61\text{ m/s}$
Why does sound travel faster in moist (humid) air than in dry air? - Moist air has lower density than dry air
What effect does a change in air pressure alone have on the speed of sound at constant temperature? - No Effect
What is the normal audible frequency range for human ears? - 20 Hz to 20,000 Hz (20 kHz)
What are sound waves with frequencies below 20 Hz called? - Infrasonic Waves (Infrasound)
What are sound waves with frequencies above 20,000 Hz called? - Ultrasonic Waves (Ultrasound)
What natural phenomenon produces infrasonic acoustic waves? - Earthquakes and Volcanic Eruptions
Which animals navigate and hunt in dark environments using ultrasonic echolocation? - Bats and Dolphins
Which system uses ultrasound to detect underwater obstacles and measure sea depth? - SONAR (Sound Navigation and Ranging)
What medical diagnostic technique uses high-frequency ultrasonic waves to visualize organs? - Ultrasonography
What medical procedure uses focused ultrasonic sound waves to break down kidney stones? - Lithotripsy
Which high-frequency whistle produces ultrasonic sound used in dog training? - Galton’s Whistle
Which perceptual characteristic of sound is determined primarily by wave frequency? - Pitch (Shrillness)
Why is a woman's or child's voice generally shriller than an adult male's voice? - Higher frequency and higher pitch
Which perceptual characteristic of sound is determined by wave amplitude? - Loudness
Which property of sound allows a listener to distinguish between different musical instruments playing the same note? - Quality (Timbre)
What is the distinct repetition of sound caused by reflection from a distant obstacle called? - Echo
What is the minimum distance between source and reflector required to hear a distinct echo in air? - 17.2 meters
What is the persistence of hearing duration in the human brain? - 0.1 seconds (1/10th of a second)
What is the persistence of sound in an enclosed hall due to repeated reflections called? - Reverberation
Why are walls and ceilings of movie theaters and auditoriums covered with porous sound-absorbing materials? - To prevent excessive reverberation
What phenomenon occurs when an external driving frequency matches a system's natural frequency, causing large vibrations? - Resonance
Why are marching soldiers ordered to break step while crossing a suspension bridge? - To prevent resonance that could collapse the bridge
What is the ratio of an aircraft's speed to the speed of sound in the surrounding medium called? - Mach Number
What term describes speeds that exceed Mach 1? - Supersonic Speed
What term describes speeds that exceed Mach 5? - Hypersonic Speed
What loud explosive sound is generated on the ground when an aircraft travels faster than sound? - Sonic Boom
What is the apparent shift in sound frequency due to relative motion between source and listener called? - Doppler Effect
Why does an approaching train horn sound higher in pitch than when it moves away? - Doppler Effect
Which acoustic medical instrument functions via multiple reflections of heart and lung sounds inside hollow tubes? - Stethoscope
Why do sound waves easily bend (diffract) around open doorways compared to light waves? - Sound wavelengths are comparable in size to door openings
What is the normal intensity level of ordinary human conversation in decibels? - 40 to 60 dB
Above what continuous noise level does sound become hazardous to human hearing? - 85 dB
What decibel level marks the human threshold of physical auditory pain? - 120 dB
What parameter is calculated as the distance between two consecutive wave crests or compressions? - Wavelength ($\lambda$)
What is the mathematical relation connecting wave velocity ($v$), frequency ($f$), and wavelength ($\lambda$)? - $v = f \lambda$
What remains unchanged when a sound wave passes from air into water? - Frequency
What is the unit used to measure the pitch or frequency of sound vibrations? - Hertz (Hz)
What type of wave can propagate through liquid interiors: transverse or longitudinal? - Longitudinal Waves
Why is the lightning flash seen several seconds before thunder is heard during a storm? - Speed of light is vastly greater than speed of sound
What type of sound wave is generated across the surface of water when a stone is dropped? - Transverse and Surface Waves
What is the term for reflected sound used by marine animals and submarines to navigate? - Echolocation

7. Heat and Thermodynamics

What form of thermal energy transfers between systems due to a temperature difference? - Heat
What physical quantity measures the average kinetic energy of constituent particles in matter? - Temperature
What is the amount of heat needed to raise the temperature of 1 gram of water by $1^\circ\text{C}$ called? - Calorie
One calorie is equal to how many Joules? - 4.184 Joules
At what numerical temperature do both the Celsius and Fahrenheit scales read the exact same value? - $-40^\circ$ ($-40^\circ\text{C} = -40^\circ\text{F}$)
What is the theoretical lowest possible temperature where molecular motion ceases? - Absolute Zero (0 Kelvin or $-273.15^\circ\text{C}$)
What is the normal core body temperature of a healthy human in Celsius? - $37^\circ\text{C}$
What is the normal core body temperature of a healthy human in Fahrenheit? - $98.6^\circ\text{F}$
What is the normal core body temperature of a healthy human in Kelvin? - $310.15\text{ K}$
What is the standard temperature range marked on a clinical mercury thermometer? - $35^\circ\text{C}$ to $42^\circ\text{C}$ ($95^\circ\text{F}$ to $108^\circ\text{F}$)
Why are small gaps left between consecutive sections of steel railway tracks? - To allow for thermal expansion during hot summers
Why are metallic electric transmission wires strung loosely between utility poles? - To prevent snapping due to contraction during cold winters
At what temperature does pure liquid water reach its maximum density and minimum volume? - $4^\circ\text{C}$
What unusual behavior describes water expanding as it cools from $4^\circ\text{C}$ down to $0^\circ\text{C}$? - Anomalous Expansion of Water
How do freshwater fish and aquatic organisms survive in frozen lakes during severe winter? - Water beneath surface ice remains liquid at $4^\circ\text{C}$
Why do glass bottles completely filled with water burst when frozen in a freezer? - Water expands upon freezing below $4^\circ\text{C}$
Which mode of heat transfer in solids occurs via atomic vibrations and electron collisions without bulk motion? - Conduction
Which metal is the best conductor of heat and electricity? - Silver
Why are cooking utensils made of metals like copper and aluminum fitted with wooden or Bakelite handles? - Wood and Bakelite are thermal insulators
Which mode of heat transfer in fluids occurs via the actual circulating bulk movement of heated matter? - Convection
By which heat transfer process do domestic room heaters, geysers, and kitchen chimneys operate? - Convection
What coastal wind phenomena are driven by natural convection currents between land and sea? - Sea Breeze and Land Breeze
Which mode of heat transfer occurs through electromagnetic infrared waves without needing any medium? - Radiation
How does solar heat energy travel across the vacuum of space to reach the Earth? - Radiation
What idealized physical body absorbs all incident electromagnetic radiation falling upon it? - Blackbody
Which law of radiation states that good absorbers of heat are also good emitters? - Kirchhoff’s Law of Radiation
Why is wearing white or light-colored clothing preferred during hot sunny summers? - White surfaces reflect radiant heat
Why are dark or black clothes preferred during cold winters? - Dark surfaces absorb radiant heat
Why is the exterior bottom surface of cooking pans often made rough and black? - To absorb radiant heat rapidly
Which law states that total heat radiated per second by a blackbody is proportional to $T^4$? - Stefan-Boltzmann Law
Which law states that the rate of cooling of a body is proportional to the temperature difference with surroundings? - Newton’s Law of Cooling
Which device minimizes heat transfer by conduction, convection, and radiation using a vacuum and silvered walls? - Thermos Flask (Dewar Flask)
What is the heat energy required to raise the temperature of 1 kg of a substance by 1 Kelvin called? - Specific Heat Capacity
Why is water widely used as an engine coolant in automobiles? - High Specific Heat Capacity ($4184\text{ J/kg}\cdot\text{K}$)
Why is warm water used in hot water bags for pain relief compresses? - Water retains heat for a long duration due to high specific heat
What is the heat absorbed or released during a phase change at constant temperature called? - Latent Heat
What is the latent heat of fusion of ice at $0^\circ\text{C}$ in calories per gram? - $80\text{ cal/g}$ ($3.34 \times 10^5\text{ J/kg}$)
What is the latent heat of vaporization of water at $100^\circ\text{C}$ in calories per gram? - $540\text{ cal/g}$ ($2.26 \times 10^6\text{ J/kg}$)
Why do steam burns at $100^\circ\text{C}$ cause more severe tissue injury than boiling water at $100^\circ\text{C}$? - Steam releases an extra 540 cal/g of latent heat upon condensing
What spontaneous surface cooling process occurs in liquids at temperatures below the boiling point? - Evaporation
Why does water stored in a porous earthen pot (matka) remain cool during summer? - Continuous evaporation through pores extracts latent heat
Why does human sweating (perspiration) cool the skin surface on a hot day? - Evaporating sweat draws latent heat of vaporization from the body
What direct phase transition turns a solid into gas without passing through a liquid phase? - Sublimation
Name a common domestic household substance that undergoes sublimation when exposed to air. - Camphor (or Naphthalene)
What is dry ice chemically composed of? - Solid Carbon Dioxide ($\text{CO}_2$)
Which thermodynamic law provides the basis for the definition of temperature (thermal equilibrium concept)? - Zeroth Law of Thermodynamics
Which law represents the conservation of energy applied to thermodynamic systems ($dQ = dU + dW$)? - First Law of Thermodynamics
Which thermodynamic law establishes that heat cannot spontaneously flow from a colder body to a hotter body? - Second Law of Thermodynamics
What thermodynamic property measures the degree of disorder or randomness in a closed system? - Entropy
Which liquid metal is commonly used inside traditional clinical and laboratory thermometers? - Mercury

8. Electricity and Magnetism

Which fundamental law governs the electrostatic force between two stationary point charges? - Coulomb’s Law
What is the time rate of flow of electric charge across a conductor cross-section called? - Electric Current ($I = \frac{Q}{t}$)
What is the SI unit of electric current? - Ampere (A)
What is the direction of conventional electric current relative to electron movement? - Opposite to electron drift
Which law states that current through a metallic conductor is directly proportional to voltage at constant temperature? - Ohm’s Law ($V = IR$)
What is the resistance of an ideal ammeter? - Zero
What is the resistance of an ideal voltmeter? - Infinite
How does the electrical resistance of pure metallic conductors change when temperature increases? - Increases
How does the electrical resistance of semiconductors like Silicon and Germanium change with temperature rise? - Decreases
What phenomenon describes the complete loss of electrical resistance in materials cooled below critical temperature? - Superconductivity
Who discovered the phenomenon of superconductivity in liquid-helium-cooled mercury in 1911? - Heike Kamerlingh Onnes
In which circuit arrangement does the same current flow sequentially through all connected components? - Series Circuit
In which circuit arrangement do all branches experience the same supply voltage? - Parallel Circuit
How are domestic electrical appliances in households wired together? - Parallel Circuit
What happens to the overall equivalent resistance when multiple resistors are connected in parallel? - Decreases (less than the smallest individual resistor)
Which law states that heat generated in a resistor is proportional to $I^2Rt$? - Joule’s Law of Heating
Which alloy of Nickel and Chromium is used to make heating elements in electric irons and room heaters? - Nichrome
Which metal is used for filaments in incandescent light bulbs due to its very high melting point ($3422^\circ\text{C}$)? - Tungsten
Which inert gases are filled inside incandescent bulbs to prevent filament oxidation? - Argon and Nitrogen
What two key properties must an electric safety fuse wire possess? - High Resistivity and Low Melting Point
What alloy is traditionally used in the fabrication of electric fuse wires? - Alloy of Tin (63%) and Lead (37%)
Which automatic electromagnetic/bimetallic switch has replaced sacrificial fuse wires in modern homes? - Miniature Circuit Breaker (MCB)
What is the standardized voltage and frequency of domestic AC electricity supply in India? - 220 Volts, 50 Hz
In a three-pin domestic plug, what color insulation code is used for the Earth wire in India? - Green (or Green-Yellow)
In a three-pin domestic plug, what color insulation code is used for the Live wire? - Red (or Brown)
In a three-pin domestic plug, what color insulation code is used for the Neutral wire? - Black (or Blue)
Why is the earth pin in a three-pin electrical plug made thicker and longer than the other two pins? - For early grounding safety to discharge fault currents
What is the electrical power consumed by an appliance operating at voltage $V$ with current $I$? - Power ($P = VI = I^2R$)
Who first discovered in 1820 that an electric current creates a magnetic field around it? - Hans Christian Oersted
Which rule gives the direction of concentric magnetic field lines around a straight current wire? - Right-Hand Thumb Rule
What is a tightly wound helical cylindrical coil of insulated wire that behaves like a magnet called? - Solenoid
What temporary magnet consists of a soft iron core placed inside a current-carrying solenoid? - Electromagnet
Which rule is used to determine the direction of mechanical force on a current conductor in a magnetic field? - Fleming’s Left-Hand Rule
Which device converts electrical energy into rotational mechanical energy using Fleming's Left-Hand Rule? - Electric Motor
Who discovered the phenomenon of Electromagnetic Induction (EMI) in 1831? - Michael Faraday
Which law states that the polarity of induced EMF opposes the magnetic flux change producing it? - Lenz’s Law
On which fundamental conservation principle is Lenz’s Law based? - Law of Conservation of Energy
Which rule is used to find the direction of induced electric current in a moving generator conductor? - Fleming’s Right-Hand Rule
Which electrical device converts mechanical rotational energy into electrical energy using EMI? - Electric Generator (Dynamo)
Which static device steps up or steps down alternating voltage (AC) through mutual electromagnetic induction? - Transformer
Why does a transformer fail to operate when connected across a Direct Current (DC) power source? - Steady DC produces no changing magnetic flux
What type of transformer increases alternating output voltage while lowering output current? - Step-Up Transformer
Why is long-distance electricity transmission from power stations carried out at ultra-high voltages? - To minimize $I^2R$ power loss in cables
Do isolated magnetic monopoles exist in nature? - No (Magnetic poles always exist in dipoles)
In which direction do magnetic field lines travel outside a bar magnet? - North Pole to South Pole
In which direction does a freely suspended magnetic compass needle always align itself? - Geographic North-South
Which ferromagnetic alloy of Aluminum, Nickel, and Cobalt is used to make strong permanent magnets? - Alnico
What is the critical temperature above which a ferromagnetic material loses magnetism and becomes paramagnetic? - Curie Temperature

General Science One Liners for Competitive Exams 2026