1210+ Physics Solved MCQs

601.

Which one of the following is not a Major Abiotic Factors?

A. Temperature
B. Water
C. Light
D. Air
Answer» D. Air
Explanation: Major abiotic factors include water, sunlight, oxygen, soil and temperature.
602.

Optical fibre works on the principle of

A. refraction
B. scattering
C. interference
D. total internal reflection
Answer» D. total internal reflection
Explanation: Since Torque = force x distance, to open a door easily, the handle should be fixed at the greatest distance from the hinges. If we pull with same force on a handle that is 2 feet away from the hinges, we will provide twice the torque, so it will be twice as easy to open.
603.

The colours of stars depend on their –

A. temperature
B. distance
C. radius
D. atmospheric pressure
Answer» A. temperature
Explanation: The colour of a star tells about its temperature, and the temperature depends on some combination of the star's mass and evolutionary phase.
604.

Water has maximum density at –

A. 100°C
B. 0°C
C. 4°C
D. 273°C
Answer» C. 4°C
Explanation: The maximum density of water occurs at 4 °C because at. this temperature, two opposing effects are in balance. Water is an exceptional compound that has a lower density in the solid phase than the liquid phase (i.e., ice floats on water). This is actually due to the ion nature of water in the liquid phase, which packs the molecules tightly together.
605.

Which of the following colour of light deviates least through the prism?

A. yellow
B. green
C. violet
D. red
Answer» D. red
Explanation: In refracting media like glass prism, water, etc., lights of different colors travel with different speeds. The speed of violet colour is the least, while the speed of red colour is the largest in prism. As a result, the refractive index of glass is largest for violet colour and least for red colour. So the violet colour is deviated the most, while red colour is deviated least on passing through the prism.
606.

Hydraulic brakes work on the principle of –

A. Thomson's law
B. Newton's law
C. Bernoulli's theorem
D. PascaQl's law
Answer» D. PascaQl's law
Explanation: Hydraulic brake works on Pascal's law which states that pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid such that the pressure variations remain the same.
607.

X- rays are              waves.

A. Longitudinal
B. Transverse
C. Electromagnetic
D. Elastic
Answer» C. Electromagnetic
Explanation: X-rays are a form of electromagnetic radiation as are radio waves.
608.

Which planet is nearest to the sun?

A. Earth
B. Jupiter
C. Mercury
D. Mars
Answer» C. Mercury
Explanation: At an average distance of only 57.9 million km, Mercury orbits closer to the Sun than any other planet. Mercury takes only 88 days to complete an orbit around the Sun.
609.

The moon that we see in the sky is a

A. Planet
B. Star
C. Sun
D. Satellite
Answer» D. Satellite
Explanation: The moon that we see in the sky is a satellite. It is a companion of our earth and moves round it. Like our earth, there are eight other planets that get heat and light from the sun.
610.

The absolute zero is a temperature at which .

A. molecular motion in a gas would cease
B. water freezes
C. all gases become liquid
D. all gases become solid
Answer» A. molecular motion in a gas would cease
Explanation: Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance. It is the point at which all motion in matter stops.
611.

The term "infrasonic" applied to sound refers to sound waves below -

A. 200 Hz
B. 20000 Hz
C. 20 Hz
D. 0 Hz
Answer» C. 20 Hz
Explanation: The term "infrasonic" applied to sound refers to sound waves below the frequencies of audible sound, and nominally includes anything under 20Hz.
612.

If no external force acts on a system of bodies, the total linear momentum of the system of bodies remains constant. Which law states that?

A. Newton’s first law
B. Newton’s Second Law
C. Newton’s Third Law
D. Principle of conservation of linear momentum
Answer» D. Principle of conservation of linear momentum
Explanation: Conservation of linear momentum. The principle that the linear momentum of a system has constant magnitude and direction if the system is subjected to no external force. Also called law of conservation of linear momentum
613.

A body moving in a circular path with a constant speed has a –

A. constant velocity
B. constant acceleration
C. constant kinetic energy
D. constant displacement
Answer» C. constant kinetic energy
Explanation: In circular motion, the magnitude of the velocity of the body is constant but the direction is constantly changing. This means that, even though the speed is not changing, the
614.

The large collection of stars, dust and gas held together by gravitational attraction between components is known as –

A. Cluster
B. Atmosphere
C. Galaxy
D. Sun Family
Answer» C. Galaxy
Explanation: The term galaxy refers to a large collection of stars, dust, and has clouds which are held together by gravitational attraction. The smallest galaxies may contain only a few hundred thousand stars, while the largest galaxies have thousands of billions of stars. The Milky Way galaxy contains our solar system.
615.

The working of a rocket is based on the principle of:

A. Conservation of momentum
B. Conservation of mass
C. Conservation of energy
D. Conservation of angular momentum
Answer» A. Conservation of momentum
Explanation: The operation of a rocket illustrates the conservation of momentum. Just before launching, the momentum of the rocket is zero. When the rocket is fired, it forces a jet of hot gases with a high velocity through the nozzle. The jet of gases acquires a momentum downwards. Hence, the rocket acquires a momentum of equal magnitude in opposite direction. Thus the rocket moves upwards.
616.

Light waves projected on oil surface show seven colours due to the phenomenon of

A. polarisation
B. refraction
C. reflection
D. interference
Answer» D. interference
Explanation: In physics, interference is a phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude.
617.

Which of the following has the maximum specific heat capacity?

A. water
B. piece of iron
C. piece of gold
D. chloroform
Answer» A. water
Explanation: The quantity of heat required to raise the temperature of a substance by one degree Celsius is called its specific heat capacity.
618.

Which variety of glass is heat resistant?

A. Hard glass
B. Flint glass
C. Pyrex glass
D. Bottle glas
Answer» C. Pyrex glass
Explanation: Older clear-glass Pyrex manufactured by Corning, Arc International's Pyrex products, and Pyrex laboratory glassware are made of borosilicate glass.
619.

The waves used in sonography are –

A. Micro waves
B. Infra-red waves
C. Sound waves
D. Ultrasonic waves
Answer» D. Ultrasonic waves
Explanation: Sonography is an ultrasound- based diagnostic imaging technique used for visualizing internal body structures including tendons, muscles, joints, vessels and internal organs for possible pathology or lesions.
620.

Which of the following is a scalar quantity?

A. Velocity
B. Force
C. Angular momentum
D. Electrostatic potential
Answer» C. Angular momentum
Explanation: The electrostatic potential at any point in an electric field is defined as the work done in bringing a unit positive charge from infinity to that point against the electric force of the field.
621.

The sky appears blue due to –

A. Rayleigh scattering
B. Mie scattering
C. Back scattering
D. None of the above
Answer» A. Rayleigh scattering
Explanation: The blue colour of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air. However, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky.
622.

The device used to convert solar energy into electricity is –

A. Photovoltaic cell
B. Daniell cell
C. Electrochemical cell
D. Galvanic cell
Answer» A. Photovoltaic cell
Explanation: Sunlight is converted into electricity using photovoltaics (PV). A photovoltaic system employs solar panels composed of a number of solar cells to supply usable solar power.
623.

The absorption of ink by blotting paper involves -

A. capillary action phenomenon
B. viscosity of ink
C. siphon action
D. diffusion of ink through the blotting
Answer» A. capillary action phenomenon
Explanation: The ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity.
624.

A fuse wire is made of:

A. an alloy of tin and copper
B. an alloy of tin and lead
C. an alloy of tin and aluminium
D. an alloy of nickel and chromium
Answer» B. an alloy of tin and lead
Explanation: Electric fuse wire is an alloy made of tin (63 % lead 37 %. The cross sectional area determines the melting point at a certain current. Alloys (e.g. tin/ lead) are used due to their 'eutectic' action -i.e. the resulting combination of good conductivity (due to the tin) with a low melting point due to the lead).Q.42) Ultra violet light of Sun's radiation is prevented from reaching the earth's atmosphere by the layer of –
625.

Which instrument is used to measure depth of ocean?

A. Galvanometer
B. Fluxmeter
C. Endoscope
D. Fathometer
Answer» D. Fathometer
Explanation: Galvanometer - measures electric current, Fluxmeter - measures magnetic flux, Endoscope - used to examine internal parts of the body.
626.

When a running car stops suddenly, the passengers tends to lean forward because of:

A. centrifugal force
B. inertia of rest
C. inertia of motion
D. gravitational force
Answer» C. inertia of motion
Explanation: When a running car stops suddenly, the passengers tend to lean forward due to inertia of motion. Inertia is that property of a body due to which it resists a change in its state of rest or of uniform motion.
627.

Why the Earth is having its own atmosphere?

A. Winds
B. Clouds
C. Gravity
D. Rotation of the Earth
Answer» C. Gravity
Explanation: Due to gravity, our Earth has an atmosphere, Gravity causes the gases to be held close to the earth instead of escaping into outer space.
628.

A ray of white light strikes the surface of an object. If all the colours are reflected, the surface would appear

A. Black
B. White
C. Grey
D. Opaque
Answer» B. White
Explanation: Objects do not have any colour of their own. When light hits a surface, some of it is absorbed and some of it is reflected. The light that is reflected is the colour of the object in that light. Objects appear white when they reflect all the wavelengths; they appear black when they absorb all visible wavelengths.
629.

It is difficult to walk on ice because of.

A. absence of friction
B. less inertia
C. more inertia
D. more mass
Answer» A. absence of friction
Explanation: It's difficult to walk on ice because there's very little friction between the bottoms of your shoes and the ice. Friction is a force that opposes motion.
630.

One bar is equal to – (1) 10 ³ Pa

A. 100 Pa
B. 10 7 Pa
C. 10 ⁴ Pa
D. none
Answer» C. 10 ⁴ Pa
Explanation: The bar is a non-Si unit of pressure. It is defined by the IUPAC as exactly equal to 100,000 Pa or 1O Pa.
631.

A NOT gate can be implemented by:

A. a single diode
B. two diodes
C. a single resistor
D. a single transistor
Answer» D. a single transistor
Explanation: In digital logic, an inverter or NOT gate is a logic gate which implements logical negation. An inverter circuit outputs a voltage representing the opposite logic-level to its input. Inverters can be constructed using a single NMOS transistor or a single PMOS transistor coupled with a resistor.
632.

Persistence of vision is the Principle behind:

A. Binocular
B. Cinema
C. Periscope
D. Camera
Answer» B. Cinema
Explanation: Persistence of vision is the phenomenon of the eye by which an afterimage is thought to persist for approximately one twenty-fifth of a second on the retina. In the early days of cinema, it was scientifically determined that a frame rate of less than 16 frames per second (frame/s) caused the mind to see flashing images.
633.

Sudden fall in barometer is indication of

A. Storm
B. Rain
C. Tide
D. Clear weather
Answer» C. Tide
Explanation: Sudden fall in barometer is indication of Storm. A barometer measures air pressure: A "rising" barometer indicates increasing air pressure; a "falling" barometer indicates decreasing air pressure.
634.

If in a motion, the axis of the rotation does not pass through the object, then the motion is called -

A. Spin motion
B. Oscillatory motion
C. Translatory motion
D. Orbital motion
Answer» D. Orbital motion
Explanation: The axis of the rotation does not pass through the object in orbital motion. It involves the quantum mechanical motion of rigid particles (such as electrons) about some other mass, or about them selves.
635.

Who among the following evolved the concept of relationship between mass and energy?

A. Einstein
B. Planck
C. Dalton
D. Rutherford
Answer» A. Einstein
Explanation: Einstein correctly described the equivalence of mass and energy as “the most important upshot of the special theory of relativity” (Einstein 1919), for this result lies at the core of modern physics.
636.

Super cooling is cooling of liquid           .

A. below melting point
B. below freezing point
C. at melting point
D. above melting point
Answer» B. below freezing point
Explanation: Supercooling is the process of chilling a liquid below its freezing point, without it becoming solid.
637.

The base of an electric iron is brightly polished mainly -

A. to make it smooth and frictionless
B. to make it rust-proof
C. to reduce heat loss by radiation
D. to make it more durable
Answer» C. to reduce heat loss by radiation
Explanation: Polished surfaces are poor radiators of heat. So loss of heat on that account is reduced and the electric iron remains hotter than otherwise.
638.

Oparin's theary about origin of life' is related to -

A. chemical evolution
B. physical evolution
C. biological evolution
D. artificial evolution
Answer» A. chemical evolution
Explanation: Alexander Oparin was a Russian biochemist, notable for his contributions to the theory of the origin of life on Earth, and particularly for the primordial soup theory of the evolution of life from carbon-based molecules.
639.

Heat given to a body which raises its temperature by 1°C is known as -

A. water equivalent
B. thermal capacity
C. specific heat
D. temperature gradient
Answer» B. thermal capacity
Explanation: Heat capacity or thermal capacity is a measurable physical quantity equal to the ratio of the heat added to (or removed from) an object to the resulting temperature change.
640.

Flemings "Left hand Rule" is associated with the effect of –

A. Electric field on current
B. Magnetic field on magnet
C. Electric field on magnet
D. Magnetic Field on current
Answer» D. Magnetic Field on current
Explanation: Whenever, a current carrying conductor comes under a magnetic field, there will be force acting on the conductor and on the other hand, if a conductor is forcefully brought under a magnetic field, there will be an induced current in that conductor. In both of the phenomenon, there is a relation between magnetic field, current and force.
641.

The force which makes a vehicle to stop when break is applied is called –

A. gravitational force
B. vanderwalls force
C. frictional force
D. covalent force
Answer» C. frictional force
Explanation: A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction. When the brakes are applied, work is done by the friction force between the brakes and the wheels.
642.

In radio-communication, the signals emitted by transmitting antenna are reflected on –

A. stratosphere
B. ozonosphere
C. ionosphere
D. troposphere
Answer» C. ionosphere
Explanation: The lower atmosphere is more or less transparent to radio waves. However, the ionosphere reflects back the radio waves. Thus, a signal emitted by an antenna from a certain place can be received at another place on the surface of Earth in the following two ways: ground wave propagation and sky wave propagation.
643.

While cooking, if the bottom of the vessel is getting blackened on the outside, it means that

A. The food is not cooked completely
B. The fuel is not burning completely
C. The fuel is wet
D. The fuel is burning completely
Answer» B. The fuel is not burning completely
Explanation: If we observe the bottoms of cooking vessels getting blackened, it means that the air holes are blocked and fuel is getting wasted.
644.

If electrical conductivity increases with the increase of temperature of a substance, then it is a

A. Conductor
B. Semiconductor
C. Insulator
D. Carborator
Answer» B. Semiconductor
Explanation: A solid substance that has conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects.
645.

Automatic wrist watches get energy from -

A. twist in spring
B. liquid crystal
C. kinetic energy
D. movement of our hands
Answer» A. twist in spring
Explanation: An automatic watch is a watch that continues to operate due to the regular motion of the wearer's wrist.
646.

Radian is used to measure -

A. Temperature
B. Intensity of Flame
C. Angle
D. Solid Angle
Answer» C. Angle
Explanation: Kelvin is used to measure Temperature, Candela is used to measure Intensity of flame, Steredian is used to measure Solid Angle.
647.

Which one of the following types of glass can cut off ultraviolet rays?

A. Soda glass
B. Pyrex glass
C. Jena glass
D. Crookes glass
Answer» D. Crookes glass
Explanation: In this glass mainly cerium oxide (CiO2) is present which sharply absorbs the ultraviolet rays from the sunlight so utilized in making lenses of eye glasses.
648.

Light year is a unit of –

A. Light
B. Current
C. Distance
D. Time
Answer» C. Distance
Explanation: A light-year is a unit of length used informally to express astronomical distances. It is equal to just under 10 trillion kilometres.
649.

The word 'insulation' means –

A. matters which insulate
B. incoming solar radiation
C. insoluble matters
D. None of the above
Answer» B. incoming solar radiation
Explanation: Insolation is the solar radiation that reaches the earth's surface. It is measured by the amount of solar energy received per square centimeter per minute. Insolation affects temperature. The more the insolation, the higher is the temperature.
650.

Which of the following is not a vector quantity?

A. Speed
B. Velocity
C. Torque
D. Displacement
Answer» A. Speed
Explanation: Speed is a scalar quantity that refers to "how fast an object is moving." Speed can be thought of as the rate at which an object covers distance. It does not keep track of direction. In contrast, velocity is a vector quantity as it is direction aware.
651.

An object with a constant speed –

A. is not accelerated
B. might be accelerated
C. is always accelerated
D. also has a constant velocity
Answer» A. is not accelerated
Explanation: Acceleration is defined as the rate at which an object changes its velocity. An object is accelerating if it is changing its velocity. An object with constant speed will have no acceleration as the speed is uniform.
652.

The instrument used to regulate temperature to a particular degree is called :

A. Thermostat
B. Thermometer
C. Pyrometer
D. Thermocouple
Answer» A. Thermostat
Explanation: A thermostat is a component which senses the temperature of a system so that the system's temperature is maintained near a desired set point. At its core, a thermostat is simply the controls used to regulate temperature in a heating system.
653.

The power dissipated in a resistance is given by?

A. V²/R
B. IV
C. All of these
D. I²R
Answer» C. All of these
Explanation: Any resistor in a circuit that has a voltage drop across it dissipates electrical power. This electrical power is converted into heat energy hence all resistors have a power rating.
654.

The technique used by bats to find their way or to locate food is               .

A. SONAR
B. RADAR
C. Echolocation
D. Flapping
Answer» C. Echolocation
Explanation: Bats use echolocation to navigate and find food in the dark. To echolocate, bats send out sound waves from their mouth or nose. When the sound waves hit an object they produce echoes.
655.

In the absence of the earth's atmosphere, sky would appear –

A. blue
B. deep red
C. white
D. black
Answer» D. black
Explanation: Sky appears blue because the tiny particles of the earth's atmosphere scatter the blue colour (short wavelength) of the sunlight more dominantly than other wavelengths. A blue sky is a manifestation of Rayleigh scatter. The sky would appear black in the absence of earth's atmosphere because there would be no particles to scatter the light.
656.

If ice floating on water in a vessel melts, the water level in the vessel -

A. increases
B. does not change
C. first increases before decreasing
D. decreases
Answer» B. does not change
Explanation: When ice floating on water in a vessel melts, the water level in the vessel does not change. This is because when floating, the ice displaces an amount of water equal to its mass, and when melted, it becomes an amount of water equal to its mass. It is accordance with Archimedes Principle, which states that the mass of the liquid displaced by a floating object is equivalent to the mass of the object.
657.

One micron is equal to-

A. 1/10th of mm
B. 1/100th of mm
C. 1/1000th of mm
D. 1/10000th of mm
Answer» C. 1/1000th of mm
Explanation: In the U.S. the thickness of paint is expressed in mils (one mil equals 1/1000 of inch). The rest of the world expresses coating thickness in microns (1 micron = 1 millionth of a meter and 25.4 microns = .001” inch or 1 mil).
658.

Quality of a musical note depends on –

A. Fundamental frequency
B. Amplitude of the wave
C. Harmonics present
D. Velocity of sound in the medium
Answer» C. Harmonics present
Explanation: Sound "quality" or "timbre" describes those characteristics of sound which allow the ear to distinguish sounds which have the same pitch and loudness. Timbre is mainly determined by the harmonic content of a sound and the dynamic characteristics of the sound such as vibrato and the attack-decay envelope of the sound. Harmonic content is the most important of these.
659.

Silicon is used in which of the following?

A. Semiconductors
B. solar energy devices
C. transistors
D. All of these
Answer» D. All of these
Explanation: Silicon is a chemical element (its symbol in chemical formula expressions is "Si") that is present in sand and glass and which is the best known semiconductor material in electronic components. Its atomic number is 14.
660.

The frequency of direct current is     .

A. Zero
B. 50 HZ
C. 60 HZ
D. 100 HZ
Answer» A. Zero
Explanation: Direct Current (DC) refers to power systems that use only one polarity of voltage or current, and to refer to the constant, zero-frequency, or slowly varying local mean value of a voltage or current.
661.

For photoelectric effect to take place, the metal used as the cathode should have –

A. high melting point
B. low melting point
C. low work function
D. low resistance
Answer» C. low work function
Explanation: The photoelectric effect is the propensity of high-energy electromagnetic radiation to eject electrons from a given material. The photoelectric effect has been utilized in devices called photocells, consisting of two electrodes in a sealed vacuum tube.
662.

If electric resistance is to be decreased, then the number of resistances should be connected in –

A. Series
B. Parallel
C. Mixed arrangement
D. None of these
Answer» B. Parallel
Explanation: Resistors are in parallel when each resistor is connected directly to the voltage source by connecting wires having riegligible resistance. Each resistor thus has the full voltage of the source applied to it. When resistors are connected in parallel, more current flows from the source than would flow for any of them individually, so the total resistance is lower. Each resistor in parallel has the same full voltage of the source applied to it, but divide the total current amongst them
663.

The material used in electric heater is

A. Tungsten
B. Nichrome
C. Brass
D. Steel
Answer» B. Nichrome
Explanation: Due to its resistance to oxidation and stability at high temperatures, Nichrome is widely used in electic heating elements, such as in appliances and tools. Typically, nichrome is wound in coils to a certain electrical resistance, and current is passed through it to produce heat.
664.

The rate of change of displacement is called:

A. Acceleration
B. Speed
C. Distance
D. Velocity
Answer» D. Velocity
Explanation: In considering motions of objects over time the instantaneous velocity of the object is the rate of change of the displacement as a function of time.
665.

The direction of heat flow between two objects depends on -

A. Their masses
B. Their heat contents
C. Their temperatures
D. Whether they are in solid, liquid or gaseous state
Answer» C. Their temperatures
Explanation: Heat always flows from a body at higher temperature to a body at a lower temperature.
666.

A man in a train moving with a constant velocity drops a ball on the platform. The path of the ban as seen by an observer standing on the platform is –

A. A straight line
B. A circle
C. A parabola
D. None of these
Answer» C. A parabola
Explanation: In the reference frame of the platform the ball has initial horizontal velocityequal to the velocity of the train. The vertical direction is the same observed on the train because both observers agree that gravity is acting on the ball causing an acceleration g.
667.

Which of the following is responsible for permanent hardness of water?

A. magnesium bicarbonate
B. sodium chloride
C. calcium sulphate
D. calcium bicarbonate
Answer» C. calcium sulphate
Explanation: Permanent hardness is caused by dissolved calcium sulfate (which is not removed by boiling). Hard water contains dissolved magnesium and calcium ions. These make it more difficult for the water to form lather with soap. Temporary hardness is caused by dissolved calcium hydrogen carbonate (which is removed by boiling)
668.

While ascending a hill, the driver of the vehicle keeps the gear ratio –

A. equal to 1
B. less than 1
C. greater than 1
D. either equal to or greater than 1
Answer» D. either equal to or greater than 1
Explanation: While ascending a hill Gear Ratio should be "Either equal to or greater than 1?. Gear Ratio is the ratio between angular velocity of input gear to the angular velocity of output gear. It prevents the vehicle from stalling.
669.

A wire of resistance R is cut into ‘n’ equal parts. These parts are then connected in parallel. The equivalent resistance of the combination will be –

A. nR
B. R/n
C. n/R
D. R/n²
Answer» D. R/n²
Explanation: Since R is directly proportional to length of the wire, when wire is cut into equal parts, then Resistance of each part = R/n
670.

What is unit of Electrical Capacity?

A. henry
B. farad
C. volt
D. ohm
Answer» B. farad
Explanation: Henry is unit of Magnetic Induction, volt is unit of Potential Difference, ohm is unit of Electric Resistance.
671.

Work done upon a body             .

A. only a vector quantity
B. only a scalar quantity
C. both vector and scalar
D. neither vector nor scalar
Answer» B. only a scalar quantity
Explanation: 0
672.

With the increase of pressure, the boiling point of any substance -

A. Increases
B. Decreases
C. Remains Same
D. Becomes zero
Answer» A. Increases
Explanation: The temperature stays the same until all the liquid has vaporized. As the temperature of a liquid rises, the pressure of escaping vapor also rises, and at the boiling point the pressure of the escaping vapor is equal to that exerted on the liquid by the surrounding air, causing bubbles to form.
673.

When a particle and an antiparticle come in contact with each other, they

A. repell each other
B. annihilate each other
C. go undisturbed
D. spin about a common axis
Answer» B. annihilate each other
Explanation: 0
674.

Photon is the fundamental unit/ quantum of –

A. gravitation
B. electricity
C. magnetism
D. light
Answer» D. light
Explanation: A photon is an elementary particle, the quantum of light and all other forms of electromagnetic radiation. The modern photon concept was developed gradually by Albert Einstein.
675.

Time of exposure required for taking photograph of an object depends upon the –

A. brightness of the object
B. skill of photographer
C. proximity of object
D. size of the object
Answer» A. brightness of the object
Explanation: In photography, shutter speed or exposure time is the effective length of time a camera's shutter is open. The total exposure is proportional to this exposure time, or duration of light reaching the film or image sensor. The correct exposure for a particular object dependson the brightness of the object to be photographed.
676.

The ordinary and maximum tolerance limit of sound by human being is –

A. 50 db to 70 db (decibel)
B. 60 db to 80 db (decibel)
C. 65 db to 75 db (decibel)
D. 70 db to 85 db (decibel)
Answer» B. 60 db to 80 db (decibel)
Explanation: Normal speech is about 60 dB (decibels). A dangerous sound is anything that is 80 dB or higher which can lead to hearing loss. At 70 dB or lower, the risk of harm to healthy ears is negligible. Listening to sound above 80 decibels can cause profound deafness.
677.

Which is best used as a sound absorbing material in partition walls?

A. Stone chips
B. Steel
C. Glass - wool
D. Glass pieces
Answer» C. Glass - wool
Explanation: Materials that do not transfer mechanical energy well. These tend to be soft, flexible, low density, and with high surface area to linear area ratios.
678.

The best conductor of electricity among the following is -

A. copper
B. iron
C. aluminum
D. silver
Answer» D. silver
Explanation: Copper and Silver Are Most Common. Silver is the best conductor of electricity because it contains a higher number of movable atoms (free electrons).
679.

Light Emitting Diodes (LED) is used in fancy electronic devices such as toys emit

A. X-rays
B. ultraviolet light
C. (4) All of the above
D. radio waves
Answer» D. radio waves
Explanation: A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. Infrared LEDs are used in remote-control circuits, such as those used with a wide variety of consumer electronics.
680.

The primary colours in photography are –

A. Red, Blue, Yellow
B. Red, Yellow, Green
C. Red, Blue, Green
D. Blue, Yellow, Green
Answer» A. Red, Blue, Yellow
Explanation: There are three primary colours of Red, Green and Blue (ROB). As these are mixed they form lighter colours, and when all three are mixed together they appear as white. Artists and graphic designers, who work with paintings and illustrations more than they do with photographs, often refer to Red, Yellow and Blue as the primary colours.
681.

Two electrons in an orbital are differentiated by which of the following?

A. Magnetic quantum number
B. Spin quantum number
C. Principal quantum number
D. Azimuthal quantum number
Answer» B. Spin quantum number
Explanation: Spin quantum number is the fourth quantum number that differentiates two electrons in the same orbital.
682.

Stress can be defined as              quantity.

A. Scalar
B. Vector
C. Phasor
D. Tensor
Answer» D. Tensor
Explanation: Stress is defined as Resisting force per unit area of an element, on which load is applied. Stress is always perpendicular to a cross-section in the element. It is neither scalar (it cannot be numerically added), nor is it a vector (it does not follow the triangle rule of vector addition). It is a tensor quantity because it describes things happening in two directions simultaneously.
683.

Which of the following property of sound is affected by change in air temperature –

A. Frequency
B. Intensity
C. Amplitude
D. Wavelength
Answer» D. Wavelength
Explanation: The wavelength of sound changes with temperature. This is because the speed of sound changes with the temperature. Since the speed of sound is different at different temperature, this means the wavelength of sound at a given frequency is a variable depending on the speed of sound. For example, the wavelength of a 100 cycle tone in air at 68°F would be 11.27 feet while the same tone in fresh water at 68°F would have a wavelength of 48.05 feet.
684.

Vehicles use               to see the objects coming from behind.

A. Concave lens
B. Convex lens
C. Convex mirror
D. Concave mirror
Answer» B. Convex lens
Explanation: Convex mirror is used in rear view mirror of vehicles; so that the driver can see the traffic coming from behind. The field of view is widest in case of a convex mirror, which enables it to show a wider area from behind.
685.

If electrical conductivity increases with the increase of temperature of a substance, then it is a:

A. Conductor
B. Semiconductor
C. Insulator
D. Carborator
Answer» B. Semiconductor
Explanation: A solid substance that has conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects
686.

Transition ions absorb light in –

A. infrared region
B. ultraviolet region
C. microwave region
D. visible region
Answer» D. visible region
Explanation: Transition metal ions have an incomplete set of 3d electrons. Changes in the energy of these electrons correspond to the energy of visible light. The absorption of visible light by these ions lend colour to gems.
687.

If a body weighs 12N on the surface of the earth, how much will it weigh on the surface of the moon where acceleration due to gravity is only one-sixth of that on earth's surface?

A. 12N
B. 2N
C. 10N
D. 6N
Answer» B. 2N
Explanation: Weight is mass x g. Since mass is constant and g is only 16thof that on the earth. The weight on the moon is only 16th of that on the earth.
688.

'Kilowatt-hour' is the unit of -

A. potential difference
B. electric power
C. electric energy
D. electric potential
Answer» C. electric energy
Explanation: The kilowatt hour (symbolized kW h as per SI) is a composite unit of energy equivalent to one kilowatt (1 kW) of power sustained for one hour.
689.

If the temperature inside a room is increased, the relative humidity will             ?

A. increase
B. decrease
C. remain unchanged
D. none of these
Answer» B. decrease
Explanation: This is because temperatures in the home can be much different than the temperature outside. This is because of that important relationship between temperature and how much maximum moisture can be in the air.
690.

The device used to change the speed of an electric fan is -

A. Amplifier
B. Regulator
C. Switclh
D. Rectifier
Answer» B. Regulator
Explanation: Regulator is to adjust the voltage across the motor of the fan.
691.

The required DC voltage for arc welding is-

A. 6 to 9 V
B. 50 to 60 V
C. 200 to 250 V
D. 90 to 100 V
Answer» C. 200 to 250 V
Explanation: 0
692.

What is the base of the Octal Numeral System?

A. 8
B. 16
C. 32
D. 64
Answer» A. 8
Explanation: The octal numeral system is the base-8 number system and uses the digits 0 to 7. As it uses only eight digits (0 through 7) there are no numbers or letters used above 8.
693.

A wire carrying current is –

A. positively charged
B. negatively charged
C. neutral
D. charged with a type depending upon current strength
Answer» C. neutral
Explanation: 0
694.

A light ray travelling from denser to rarer medium at an angle of incidence more than critical angle of concerned media pair suffers.

A. reflection
B. refraction
C. diffraction
D. total internal reflection
Answer» D. total internal reflection
Explanation: If the angle of incidence of light ray in the denser medium is greater than the critical angle of the concerned media pair, the light is not at all reflected in to the rarer medium but is totally reflected. This is known as 'total internal reflection'.
695.

Which of the following physical quantities has no dimension?

A. Force
B. Momentum
C. Impulse
D. Angle
Answer» D. Angle
Explanation: Quantities having units, but no dimensions: Plane angle, angular displacement, solid angle. These physical quantities possess units but they does not possess dimensional formulas.
696.

Which of the following is a good conductor of heat but bad conductor of electricity?

A. mica
B. asbestos
C. celluloid
D. paraffin wax
Answer» A. mica
Explanation: Mica is a good conductor of heat but bad conductor of electricity.
697.

Respiration in the absence of air is called -

A. Aerobic respiration
B. Anaerobic respiration
C. Muscular respiration
D. Molecular respiration
Answer» B. Anaerobic respiration
Explanation: Respiration in the absence of air is called Anaerobic respiration while respiration in the presence of air (oxygen) is called aerobic respiration.
698.

Which one among the following is responsible for formation of "Ozone Holes" in the atmosphere?

A. Benzopyrene
B. Hydrocarbons
C. Chlorofluorocarbons
D. UV radiation
Answer» C. Chlorofluorocarbons
Explanation: Chlorofluorocarbon (CFCs), commonly known by the DuPont brand name Freon, are considered as one of the ozone- depleting substances.
699.

An alloy is an example of :

A. Colloidal solution
B. Emulsion
C. Solid solution
D. Heterogeneous mixture
Answer» C. Solid solution
Explanation: A Solid solution is a uniform mixture of substances in solid form.
700.

Hydrogen atom is excited from ground state to another state with principal quantum number equal to 4. Then the number of spectral lines in the emission spectra will be -

A. 2
B. 6
C. 5
D. 3
Answer» B. 6
Explanation: Number of spectral lines from a state n to ground state is
= n (n-1)/2
=4(4-1)/2=12/2
=6
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