McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: General Knowledge (GK) .
| 751. |
When a body is immersed in a liquid, the force acting on it is – |
| A. | Upthrust |
| B. | Weight |
| C. | Mass |
| D. | Both (1) and (2) |
| Answer» D. Both (1) and (2) | |
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Explanation: According to the Principle of Flotation, when a body is immersed in a fluid, two forces act on it: ( 1) The weight of the body acting vertically downward through the centre of gravity of the body, and (2) The upthrust of the fluid acting vertically upward through the centre of gravity of the fluid displaced, i.e., centre of buoyancy. The upthrust is also termed as buoyant force. |
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| 752. |
Tesla is a unit of magnetic – |
| A. | flux |
| B. | induction |
| C. | moment |
| D. | field |
| Answer» D. field | |
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Explanation: The tesla (symbol T) is the SI derived unit used to measure magnetic fields. Testa can be measured in different ways; for example, one tesla is equal to one Weber per square meter. The tesla was first defined in 1960 by the General Conference on Weights and Measures (CGPM). It was named in honor of the physicist electrical engineer, and inventor, Nikola Tesla. |
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| 753. |
The damage of the human body due to radiation (X-rays or y-rays etc,) is measured in – |
| A. | Rems |
| B. | Roentgen |
| C. | Curie |
| D. | Rads |
| Answer» A. Rems | |
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Explanation: In the case of damage to human body due to radiation, the most important factor is the amount of the dose - the amount of energy actually deposited in the body. The absorbed radiation dose, the amount of energy absorbed per gram of body tissue, is usually measured in units called rads. Another unit of radation is the rem, or roentgen equivalent in man. For practical purposes, 1 rad (absorbed dose) = 1 rem or 1000 mrem (dose equivalent) (Source: United States Nuclear Regulatory Commission). |
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| 754. |
Golden view of sea shell is due to - |
| A. | Diffraction |
| B. | Dispersion |
| C. | Polarization |
| D. | Reflection |
| Answer» C. Polarization | |
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Explanation: When a ray of light falls on sea shell, its small amount gets refracted (slightly polarized) and rest almost gets reflected back (fully polarized). So it gets a golden view because of polarization. |
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| 755. |
An object covers distance which is directly proportional to the square of the time. Its acceleration is – |
| A. | increasing |
| B. | decreasing |
| C. | zero |
| D. | constant |
| Answer» D. constant | |
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Explanation: When an object covers distance which is directly proportional to the square of the time, its acceleration is constant. This is seen in the cases of falling objects. This connection between time and distance was first observed by Galileo. |
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| 756. |
What is impulse equal to? |
| A. | Change in momentum |
| B. | Change in force |
| C. | Change in velocity |
| D. | Change in acceleration |
| Answer» A. Change in momentum | |
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Explanation: Impulse is a quantity that describes the effect of a net force acting on an object. The impulsemomentum theorem states that the change in momentum of an object equals the impulse applied to it. |
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| 757. |
The person suffering from “myopia” cannot see the objects at: |
| A. | Near distance |
| B. | Longer distance |
| C. | any distance |
| D. | Close to eye |
| Answer» B. Longer distance | |
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Explanation: Nearsightedness, also known as myopia, is a common type of refractive error where close objects appear clearly, but distant objects appear blurry. |
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| 758. |
Which one of the following is a non- dimensional quantity? |
| A. | Gas constant |
| B. | Strain |
| C. | Co-efficient of viscosity |
| D. | Plank's constant |
| Answer» B. Strain | |
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Explanation: A dimensionless quantity is simply a quantity that has no units and therefore no dimensions. A ratio between two numbers is a non-dimensional or dimensionless quantity. Strain which is defined as change in dimension over original dimension has no dimensional formula. So it is a. dimensionless quantity. |
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| 759. |
When water freezes its density – |
| A. | Decreases |
| B. | Becomes Zero |
| C. | Remains constant |
| D. | Increases |
| Answer» A. Decreases | |
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Explanation: Water at ordinary temperatures contracts and in-creases in density as it is cooled, like most substances. But at about 4°C it reaches a maximum density and then decreases in density as it approaches the freezing point. This is referred to as anomalous property of water. |
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| 760. |
Which of the following is the unit of perceived loudness of sound? |
| A. | Decibel |
| B. | Sone |
| C. | Hertz |
| D. | Phon |
| Answer» B. Sone | |
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Explanation: Loudness is a subjective characteristic of a sound (as opposed to the sound-pressure level in decibels, which is objective and directly measurable). Perceived loudness of sound is a psycho-acoustic quantity that depends on sound pressure level, the frequency spectrum, and the time behavior of the sound in question. |
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| 761. |
The element required for Solar energy conversion - |
| A. | Beryllium |
| B. | Silicon |
| C. | Tantalum |
| D. | Ultra pure carbon |
| Answer» B. Silicon | |
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Explanation: Energy conversion. n. (General Physics) is the process of changing one form of energy into another, such as nuclear energy into heat or solar energy into electrical energy. |
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| 762. |
The washing machine works on the principle of – |
| A. | Dialysis |
| B. | Diffusion |
| C. | Reverse osmosis |
| D. | Centrifugation |
| Answer» D. Centrifugation | |
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Explanation: Washing machines work on the principle of centrifugation. They are based onmedium sized centrifuges that put an object in rotation around a fixed axis, applying force perpendicular to the axis. |
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| 763. |
The 'Choke' used with a tube light is basically – |
| A. | an inductor |
| B. | a capacitor |
| C. | a transformer |
| D. | a resistor |
| Answer» A. an inductor | |
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Explanation: In electronics, a choke is an inductor used to block higher-frequency alternating current (AC) in an electrical circuit, while passing lower-frequency or direct current (DC). In a tubelight, the high voltage is created by suddenly interrupting the current in choke, which is connected in series with the tubelight. |
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| 764. |
The temperature of a liquid is 32° F. What is its temperature in Celsius scale? |
| A. | 32° C |
| B. | 0° C |
| C. | 100° C |
| D. | 212° C |
| Answer» B. 0° C | |
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Explanation: 0 |
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| 765. |
Which of the following phenomenon helps to conclude that light is a transverse wave? |
| A. | interference |
| B. | diffraction |
| C. | polarization |
| D. | refraction |
| Answer» C. polarization | |
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Explanation: The phenomena of interference and diffraction of light were successful beyond doubt to prove that light is a form of wave. But they failed to decide whether light is transverse or longitudinal wave. The fact that light is a transverse wave was established only after the discovery of the phenomenon of polarization. |
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| 766. |
Plank's constant has the dimensions of |
| A. | energy |
| B. | linear momentum |
| C. | angular momentum |
| D. | force |
| Answer» A. energy | |
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Explanation: The Planck's constant (h) can be defined as a pro-portionality constant that relates the energy (E) of a photon to the frequency (?) of its associated electro-magnetic wave. Mathematically, Planck's Constant (h) = Energy (E)/frequency (?). The Planck constant is named after Max Planck, the instigator of quantum theory, who discovered it in 1900. |
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| 767. |
When number of turns in a coil is trippled, without any change in the length of coil, its self inductance becomes? |
| A. | Nine times |
| B. | Three times |
| C. | Six times |
| D. | One-third |
| Answer» A. Nine times | |
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Explanation: 0 |
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| 768. |
The abbreviation LHC stands for which machine? |
| A. | Light Heat Collider |
| B. | Large Hadron Collider |
| C. | Long Heavy Collider |
| D. | Large High Collider |
| Answer» B. Large Hadron Collider | |
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Explanation: LHC stands for Large Hadron Collider is the world's largest and most powerful particle collider that allows scientists to further test the properties of the Higgs boson. It lies in a tunnel beneath the FranceSwitzerland border near Geneva, Switzerland. |
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| 769. |
Which of the following have the same unit? |
| A. | Work and power |
| B. | Torque and moment of inertia |
| C. | Work and torque |
| D. | Torque and angular momentum |
| Answer» C. Work and torque | |
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Explanation: The SI unit of work is the Newton-metre or joule (J). A Newton meter is also the SI unit of torque (also called "moment" or "moment of force"). |
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| 770. |
In a particular system, the units of length, mass and time are chosen to be 10 cm, 10 g and 0.1 s respectively. The unit of force in this system will be equivalent to – |
| A. | 0.1 N |
| B. | 1 N |
| C. | 10 N |
| D. | 100 N |
| Answer» A. 0.1 N | |
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Explanation: 0 |
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| 771. |
Relative humidity is expressed as – |
| A. | Grams |
| B. | Kilograms |
| C. | Percentage |
| D. | Ratio |
| Answer» C. Percentage | |
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Explanation: Relative humidity is the amount of moisture in the air compared to what the air can "hold" at that temperature. It signifies the mass of water vapour present in the air expressed as a percentage of the mass that would be present in an equal volume of saturated air at the same temperature. |
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| 772. |
Why is weightlessness experienced while orbiting the earth in space ships? |
| A. | Inertia |
| B. | Acceleration |
| C. | Zero gravity |
| D. | None of these |
| Answer» D. None of these | |
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Explanation: The reason astronauts experience weightlessness which orbiting the earth in spaceships is that they are in free fall. A spacecraft in orbit is falling towards the Earth, because of gravity, but it is moving forward in its orbit fast enough that the path it follows is a curve that is a closed ellipse. |
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| 773. |
Where is a transistor most likely to be found? |
| A. | Wrist watch |
| B. | Fuse |
| C. | Hearing aid |
| D. | Fluorescent lamp |
| Answer» C. Hearing aid | |
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Explanation: A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. The transistor invented in 1948 was well suited to the hearing aid application due to low power and small size; hearing aids were an early adopter of transistors. Transistors replaced the need for batteries in hearing aids |
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| 774. |
What is the SI unit of electric current? |
| A. | Amperes |
| B. | Coulombs |
| C. | Joules |
| D. | Watts |
| Answer» A. Amperes | |
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Explanation: The SI unit for measuring an electric current is the am pere, which is the flow of electric charge across a surface at the rate of one coulomb per second. |
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| 775. |
An object is in static equilibrium when it is . |
| A. | at rest |
| B. | moving in a circular path |
| C. | moving with uniform velocity |
| D. | accelerating at high speed |
| Answer» A. at rest | |
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Explanation: When forces acting on an object which is at rest are balanced, the object is said to be in a state of static equilibrium. The resultant of these forces equals zero. |
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| 776. |
Equal volumes of different gases at any definite temperature and pressure have- |
| A. | Equal weights |
| B. | equal masses |
| C. | equal density |
| D. | equal no. of molecules |
| Answer» D. equal no. of molecules | |
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Explanation: 0 |
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| 777. |
Which law states, "The rate of loss of heat by a body is directly proportional to the difference in temperature between the body and the surroundings"? |
| A. | Doppler's Effect |
| B. | Newton's law of cooling |
| C. | Kirchhoff's Law |
| D. | Stefan's Law |
| Answer» B. Newton's law of cooling | |
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Explanation: Newton's Law of Cooling states that the rate of change of the temperature of an object is proportional to the difference between its own temperature and the ambient temperature. |
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| 778. |
Which of the following reaction is the main cause of energy radiated from Sun? |
| A. | Nuclear fission |
| B. | Nuclear fusion |
| C. | Chemical reaction |
| D. | Diffusion reaction |
| Answer» B. Nuclear fusion | |
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Explanation: The Sun is a main-sequence star, and thus generates its energy bynuclear fusion of hydrogen nuclei into helium. In its core, the Sunfuses 620 million metric tons of hydrogen each second. |
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| 779. |
Every hot object emits – |
| A. | X-rays |
| B. | Visible light |
| C. | Infrared rays |
| D. | Ultraviolet rays |
| Answer» C. Infrared rays | |
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Explanation: 0 |
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| 780. |
Postage Meter was invented by - |
| A. | Fyodor Pirotsky |
| B. | Arthur Pitney |
| C. | Fritz Pfleumer |
| D. | Stephen Perry |
| Answer» B. Arthur Pitney | |
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Explanation: The first postal meter to be commercially produced and distributed was invented by Arthur Pitney. World's first postage meter on December 9, 1901. |
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| 781. |
A solid ball of metal has a spherical cavity inside it. When the ball is heated the volume of the cavity will - |
| A. | increase |
| B. | decrease |
| C. | remain unaffected |
| D. | have its shape changed |
| Answer» A. increase | |
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Explanation: The metal ball can be considered to be made up of several layers of thinner ones. On heating each of these layers will increase in radius. |
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| 782. |
When two semiconductors of p-and n- type are brought in contact, they form p-n junction which acts like a/an – |
| A. | Conductor |
| B. | Oscillator |
| C. | Rectifier |
| D. | Amplifier |
| Answer» C. Rectifier | |
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Explanation: P-n junction is a device which flows current in one direction when it is forward biased and when it is reverse biased it doesn't flow any current through it. So it acts as an rectifier device to convert sinusoidal current to unidirection. A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. |
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| 783. |
Ohm's law is valid in case of – |
| A. | semiconductor |
| B. | conductor |
| C. | superconductor |
| D. | insulator |
| Answer» B. conductor | |
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Explanation: Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. It defines the relationship between the three fundamental, electrical quantities: current, voltage, and resistance. |
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| 784. |
The freezing point of fresh water is - |
| A. | 4°C |
| B. | 3°C |
| C. | 5°C |
| D. | 0°C |
| Answer» D. 0°C | |
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Explanation: The freezing point of water is the temperature at which water changes phase from a liquid to a solid. Under normal conditions, ordinary water freezes at 0°C, or 32°F. The temperature may be lower if supercooling occurs or if there are impurities present in the water which could cause freezing point depression to occur. |
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| 785. |
The unit of noise pollution (level) is – |
| A. | decibel |
| B. | decimal |
| C. | ppm |
| D. | None of these |
| Answer» A. decibel | |
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Explanation: Noise pollution refers to any unpleasant, damaging or irritating noise that has the potential to harm people, wildlife or the environment. The decibel (dB) is the main unit used to measure the intensity or loudness of sounds. A sound can also be measured. by its pitch, which is the frequency of sound vibrations per second. |
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| 786. |
The boiling point of water decreases at higher altitudes is due to – |
| A. | low temperature |
| B. | low atmospheric pressure |
| C. | high temperature |
| D. | high atmospheric pressure |
| Answer» B. low atmospheric pressure | |
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Explanation: At higher altitudes, the air pressure is decreased, which forces water's boiling point to lower. The air pressure decreases with altitude because of the decrease in the density of air. The lowered boiling point of water requires an increase in cooking times or temperature. |
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| 787. |
The reactivity of an ionic compound element is explained as its tendency to attain noble gas configuration. How do the elements do so? |
| A. | Lose electrons |
| B. | Gain electrons |
| C. | Both are correct |
| D. | Both are incorrect |
| Answer» C. Both are correct | |
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Explanation: The reactivity of elements is explained as their tendency to attain a completely filled outer shell. This is called as having attained noble gas configuration. Once noble gas configuration is reached, the elements lose their reactivity. |
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| 788. |
For a ray of light to suffer total internal reflection it has to pass from – |
| A. | glass to water |
| B. | water to glass |
| C. | air to water |
| D. | air to glass |
| Answer» C. air to water | |
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Explanation: Total internal reflection is an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. |
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| 789. |
For which of the following substances, the resistance decreases with increase in temperature? |
| A. | Pure silicon |
| B. | Copper |
| C. | Nichrome |
| D. | Platinum |
| Answer» C. Nichrome | |
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Explanation: Nichrome has high resistance and it is called a resistor. |
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| 790. |
A solid needle placed horizon-tally on the surface of the water floats due to – |
| A. | capillary action |
| B. | water pressure |
| C. | surface tension of water |
| D. | viscosity of water |
| Answer» C. surface tension of water | |
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Explanation: A solid needle placed horizontally on the surface of water floats due to surface tension of water. |
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| 791. |
The first equation of motion gives the relation between : |
| A. | Position and time |
| B. | Position and Velocity |
| C. | Velocity and time |
| D. | Velocity and acceleration |
| Answer» C. Velocity and time | |
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Explanation: The equation v = u + at is called Newton's first equation of motion, where, u = Initial velocity, v = Final velocity, a = acceleration and t = time. |
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| 792. |
What is the minimum distance (in metres) required to hear an echo? |
| A. | 10 |
| B. | 13 |
| C. | 17 |
| D. | 21 |
| Answer» C. 17 | |
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Explanation: The human ear cannot distinguish echo from the original direct sound if the delay is less than 1/15 of a second. The velocity of sound in dry air is approximately 343 m/s at a temperature of 25⁰C. |
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| 793. |
The intensity ratio of waves is 25:9. What is the ratio of their amplitudes? |
| A. | 50 : 18 |
| B. | 25 : 9 |
| C. | 3 : 5 |
| D. | 5 : 3 |
| Answer» D. 5 : 3 | |
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Explanation: 0 |
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| 794. |
Which of these travels in glass with minimum velocity? |
| A. | red light |
| B. | violet light |
| C. | green light |
| D. | yellow light |
| Answer» B. violet light | |
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Explanation: Red light has a longer wavelength than violet light and the other colours of visible light have intermediate wavelengths. As light passes from air into glass, there is reduction of velocity. Due to longer wave-lengths, red waves travel fastest and is refracted the least, whileviolet waves travel the slowest and is refracted the most. |
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| 795. |
The phenomenon which causes mirage is – |
| A. | Interference |
| B. | Diffraction |
| C. | Polarisation |
| D. | Total internal reflection |
| Answer» D. Total internal reflection | |
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Explanation: Mirage is caused by total internal reflection in deserts where due to heating of the earth, refractive index of air near the surface of earth becomes lesser than above it. A ray of light coming from a distant object gets refracted from a denser to a rarer medium. |
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| 796. |
Which of the following is indicated by the colour of a star? |
| A. | weight |
| B. | distance |
| C. | temperature |
| D. | size |
| Answer» C. temperature | |
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Explanation: Colour is caused by the temperature of the surface of the star. A star approximates the behavior of a black body radiator. As a black body gets hotter its color changes. Small stars are cool (less than 3000°C) with a reddish appearance, whereas big heavy stars are hot (over 30,000°C), and have a bluish glow. |
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| 797. |
For which one of the following, 'Diodes' are generally used for? |
| A. | Rectification |
| B. | Amplification |
| C. | Modulation |
| D. | Filtration |
| Answer» A. Rectification | |
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Explanation: In electronics, a diode is an electronic device that allows current to flow in one direction only. It is mainly used as a rectifier diode that lets electrical current flow in only onedirection and is mainly used for power supply operation. Rectifier diodes are used for changing alternating current into direct current. |
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| 798. |
Heat is transmitted from higher temperature to lower temperature through the actual motion of the molecules in – |
| A. | Conduction |
| B. | Convection |
| C. | Radiation |
| D. | Both conduction and convection |
| Answer» B. Convection | |
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Explanation: The process of heat transfer from one place to an-other place without the movement of particles is called conduction Example: Heat transfer through Metal rods. On the contrary, convection is the process by which heat is transmitted through a substance from a point to another due to the bodily motion of the heated particles of the substance. The fluids (liquids and gases) are heated by this process. |
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| 799. |
Which one among the following components is used as an amplifying device? |
| A. | Transformer |
| B. | Diode |
| C. | Capacitor |
| D. | Transistor |
| Answer» D. Transistor | |
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Explanation: An amplifier is an electronic device that increases the voltage, current, or power of a signal. Generally transistors are active devices that can be used with discrete components to amplify voltage, power or both depending upon the configuration. |
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| 800. |
The commonly used coolant in refrigerators is – |
| A. | Ammonia |
| B. | Nitrogen |
| C. | Freon |
| D. | Oxygen |
| Answer» C. Freon | |
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Explanation: Modem refrigerators usually use a refrigerant called FIFC-134a (1,1,1,2- Tetrafluoroethane), which does not deplete the ozone layer, instead of Freon. Freon used to be the most common refrigerant till the 1980s; however, its use has declined since |
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