McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: General Knowledge (GK) .
| 1101. |
A hydrogen balloon floats because of – |
| A. | Air pressure decreases with decrease in height |
| B. | Air pressure decreases with decrease in weight |
| C. | Weight of the balloon is less than the weight of air displaced by it |
| D. | The pressure inside the balloon is more than the pressure outside it |
| Answer» C. Weight of the balloon is less than the weight of air displaced by it | |
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Explanation: A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter. |
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| 1102. |
The term ‘equinox’ means – |
| A. | The path which the Earth takes around the Sun |
| B. | The axis of the Earth around which it rotates |
| C. | When the day and night are of equal duration |
| D. | The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon |
| Answer» C. When the day and night are of equal duration | |
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Explanation: The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and dayhave approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens. |
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| 1103. |
After long periods of use, a grey spot develops on the inside of a bulb. This is because – |
| A. | the tungsten filament evaporates and collects there |
| B. | the heat of the bulb scorches the glass at the top |
| C. | dust inside the bulb condenses on the top |
| D. | glass undergoes a change due to the heat |
| Answer» C. dust inside the bulb condenses on the top | |
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Explanation: At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails. |
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| 1104. |
The blue colour of water in the sea is due to – |
| A. | absorption of other colours except blue by water molecules |
| B. | scattering of blue light by water molecules |
| C. | reflection of blue light by impurities in sea water |
| D. | reflection of blue sky by sea water |
| Answer» A. absorption of other colours except blue by water molecules | |
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Explanation: Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the |
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| 1105. |
Why Earth is called the blue planet? |
| A. | Because of two-thirds surface covered by water |
| B. | Because of water laden clouds in the atmosphere |
| C. | Because of pollution in the atmosphere |
| D. | None of these |
| Answer» A. Because of two-thirds surface covered by water | |
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Explanation: Earth is called the blue planet because two-thirds of its surface is covered by water. |
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| 1106. |
The density of a gas is maximum at – |
| A. | Low temperature, low pressure |
| B. | Low temperature, high pressure |
| C. | High temperature, low pressure |
| D. | High temperature, high pressure |
| Answer» B. Low temperature, high pressure | |
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Explanation: The density of gases depends upon the temperature. The higher the temperature, the more the molecules are spread out and the lower the density. The result is that warm gases rise and cool gases sink. |
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| 1107. |
A person standing on a railway platform listens to the whistles of arriving and departing trains. The whistle heard is - |
| A. | the same in both cases in all respects |
| B. | of higher intensity when train arrives |
| C. | of higher pitch when train arrives |
| D. | of higher pitch when train departs |
| Answer» C. of higher pitch when train arrives | |
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Explanation: 0 |
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| 1108. |
The cause for the Tsunami, as deduced by the seismologists, is – |
| A. | Gravitational pull of the moon |
| B. | Low pressure trough in the ocean |
| C. | Deformation of sea floor and vertical displacement of water |
| D. | Sudden change in the monsoon wind |
| Answer» C. Deformation of sea floor and vertical displacement of water | |
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Explanation: Earthquakes, volcanic eruptions and other underwater explosions (including detonations of underwater nuclear devices), landslides, glacier calvings, meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami. Tsunami can be generated when the sea floor abruptly deforms and vertically displaces the overlying water. Tectonic earthquakes are a particular kind of earthquake that are associated with the Earth's crustal deformation; when these earthquakes occur beneath the sea, the water above the deformed area is displaced from its equilibrium position. |
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| 1109. |
Should cars have bumpers that collapse under impact? |
| A. | Yes, since the offending car should get damaged and pay for the mistake |
| B. | No, since it would be very expensive to get the car repaired |
| C. | No, since the colliding car would then ram into the occupants and kill them |
| D. | Yes, since they help to absorb the impact of a collision and keep the occupants safe |
| Answer» D. Yes, since they help to absorb the impact of a collision and keep the occupants safe | |
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Explanation: In automobiles, a bumper is the front-most or rear-most part., ostensibly designed to allow the car to sustain an impact without damage to the vehicle's safety systems. They are not capable of reducing injury to vehicle occupants in high-speed impacts, but are increasingly being designed to mitigate injury to pedestrians struck by cars. |
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| 1110. |
Light houses are places with powerful lights to : |
| A. | guide and resolve traffic jams in crowded metrocities during nights. |
| B. | guide and help large crowds at religious gathering during nights. |
| C. | indicate to the incoming warships, the location of a harbour during night. |
| D. | guide and warn the ships coming from different directions in the ocean. |
| Answer» D. guide and warn the ships coming from different directions in the ocean. | |
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Explanation: A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses and used as an aid to navigation for maritime pilots at sea or on inland waterways. Lighthouses mark dangerous coastlines, hazardous shoals, reefs, safe entries to harbors, and can also assist in aerial navigation. |
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| 1111. |
A bird sitting on a high tension electric wire does not get electrocuted because – |
| A. | it has high resistance |
| B. | the body is earthed |
| C. | it does not form a closed path for the flow of current |
| D. | its feet are good insulators |
| Answer» C. it does not form a closed path for the flow of current | |
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Explanation: Electricity travels from a place of high voltage to low voltage, just as water travels from high elevation to low elevation. A bird, or any living thing, that touches a wire (where electricity is moving from high voltage to low voltage) and also touches the ground (a place with no voltage) creates a path that allows the electricity to travel through that body and into the place with no voltage. When electricity travels through a body in this fashion, electrocution takes place, and the bird can die. |
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| 1112. |
A vacuum cleaner works on the principle of pressure difference. On the moon it will – |
| A. | work as efficiently as on the earth |
| B. | not work at all |
| C. | work with reduced efficiency |
| D. | work with increased efficiency |
| Answer» B. not work at all | |
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Explanation: Vacuum cleaners work by creating a lower pressure just inside the opening which touches the floor. By creating a low pressure inside the machine, higher air pressure in the room pushes its way into the vacuum cleaner, taking the dirt with it. |
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| 1113. |
When a body is taken from earth to moon – |
| A. | Mass changes but weight remains same |
| B. | Weight changes but mass remains same |
| C. | Both weight and mass change |
| D. | Both weight and mass re-main same |
| Answer» B. Weight changes but mass remains same | |
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Explanation: Mass is how much stuff we are made of, and it is the same whether we are on Earth, on the moon, on Mercury, or anywhere else one can think of. We are held on Earth by gravity. Gravity pulling on mass is our weight . |
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| 1114. |
Superconductors are those elements – |
| A. | Whose conductivity is intermediate between metals and insulators |
| B. | Whose resistance falls almost to zero at very low temperature |
| C. | Which conduct electricity only at super-high temperature |
| D. | Which conduct electricity only, at super-high temperatures |
| Answer» B. Whose resistance falls almost to zero at very low temperature | |
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Explanation: Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. |
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| 1115. |
Ail oil drop spreads over water because |
| A. | oil is lighter than water |
| B. | oil is more viscous |
| C. | oil does not mix with water |
| D. | surface tension of oil is much smaller than that of water |
| Answer» D. surface tension of oil is much smaller than that of water | |
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Explanation: Surface tension is a contractive tendency of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in the floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects (e.g. water striders) to run on the water surface. This property is caused by cohesion of similar molecules, and is responsible for many of the behaviors of liquids. |
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| 1116. |
The nature of .fuse wire is – |
| A. | high resistance and low melting point. |
| B. | high resistance and high melting point. |
| C. | low resistance and high melting point. |
| D. | low resistance and low melting point. |
| Answer» A. high resistance and low melting point. | |
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Explanation: A fuse or fusable link works by opening an electrical circuit when the current becomes too high. As the current increases, the temperature of the wire increases. So a fuse wire should have a low melting point and should beconnected in series with the appliance. Besides, it should have a comparatively high resistance. |
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| 1117. |
In a railway track, two rails are joined end to end with a gap in between them because – |
| A. | steel can be saved |
| B. | accidents due to contraction in winter can be avoided |
| C. | air-gaps are necessary for bearing the weight of running train |
| D. | accidents due to expansion in summer can be avoided. |
| Answer» D. accidents due to expansion in summer can be avoided. | |
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Explanation: The volume of materials changes depending on current temperature. Usually heat makes them expand, and cold leads them to contract. There have to be gaps to avoid strain on the tracks. The same applies in many other fields of engineering, i.e. bridge building. |
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| 1118. |
When a pall of water is swung in a vertical circle, the water does not fall out at the top of the loop when the speed is – |
| A. | below a certain minimum value irrespective of amour of water In the pail |
| B. | above a certain minimum value irrespective of amount of water in the pail |
| C. | above a certain minimum value depending on amount of water in the pail |
| D. | below a certain minimum value depending on amount of water in the pail |
| Answer» B. above a certain minimum value irrespective of amount of water in the pail | |
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Explanation: When a pail of water is swung in a vertical circle, the water does not fall out at the top of the loop when the speed is great enough. At every point in the circle the water tries to fall vertically out due to the force of gravity g but also tries to move in a straight line due to its circular motion. |
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| 1119. |
Vehicle tyres are inflated properly – |
| A. | to ensure smooth running. |
| B. | to allow the vehicle to take more load. |
| C. | to avoid skidding and to minimize friction |
| D. | to go fast and save fuel. |
| Answer» C. to avoid skidding and to minimize friction | |
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Explanation: Under-inflated tyres create more friction with the road, increasing fuel consumption by up to ten per cent and are prone to skidding on either wet or slippery surfaces. Low pressures also lead to premature wear and risk of tyre blowout or bulging. |
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| 1120. |
Refrigeration is a process which – |
| A. | kills bacteria |
| B. | slows down the bacterial growth |
| C. | Inactivates the bacteria |
| D. | Plasmolyses the bacteria |
| Answer» B. slows down the bacterial growth | |
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Explanation: Bacteria thrive in warm, moist conditions. Refrigeration allows the temperature to be lowered so far that food can be stored for days or even months. Keeping food cold (at or below 4°C) slows down bacterial growth which helps reduce the risk of food borne illness. |
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| 1121. |
The function of ball bearings in a wheel is – |
| A. | to increase friction |
| B. | to convert kinetic friction into rolling friction |
| C. | to convert static friction into kinetic friction |
| D. | just for convenience |
| Answer» B. to convert kinetic friction into rolling friction | |
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Explanation: A ball bearing is a type of rolling- element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. |
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| 1122. |
On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because – |
| A. | metals have higher thermal capacity than plastics |
| B. | plastics have a lower density than metals |
| C. | metals are good conductors of heat |
| D. | plastics have a higher thermal conductivity than metals |
| Answer» C. metals are good conductors of heat | |
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Explanation: On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body. |
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| 1123. |
The apparent weight of a person in a lift which is moving down with uniform acceleration is . |
| A. | greater than the weight when the person is stationary |
| B. | twice the weight when the person is stationary |
| C. | less than the weight when the person is stationary |
| D. | same as the weight when the person is stationary |
| Answer» C. less than the weight when the person is stationary | |
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Explanation: 0 |
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| 1124. |
Air Quality Index is - |
| A. | an air pollutant measuring machine |
| B. | a measuring scale to show quality of air |
| C. | used for measuring humidity level |
| D. | used for forecasting rain |
| Answer» B. a measuring scale to show quality of air | |
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Explanation: The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us. |
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| 1125. |
It is easy to burst a gas-filled balloon with a needle than with a nail. It is because – |
| A. | nail is more longer than needle. |
| B. | nail exerts more pressure than needle on the balloon. |
| C. | needle exerts more pressure than nail on the balloon. |
| D. | gas is reactive with the needle. |
| Answer» C. needle exerts more pressure than nail on the balloon. | |
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Explanation: It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area). |
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| 1126. |
For a body floating in water, the apparent weight is equal to - |
| A. | Actual weight of the body |
| B. | Zero |
| C. | Weight of the body minus weight of the liquid |
| D. | Weight of the body plus upward thrust |
| Answer» C. Weight of the body minus weight of the liquid | |
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Explanation: 0 |
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| 1127. |
The characteristic invalid for heat radiation is that it travels – |
| A. | in a straight line |
| B. | in all directions |
| C. | with the speed of light |
| D. | heating the medium through which it passes |
| Answer» C. with the speed of light | |
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Explanation: Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature. |
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| 1128. |
The method of magnetization is: |
| A. | hammering a magnet |
| B. | heating a magnet |
| C. | passing direct current through it |
| D. | passing alternating current through it |
| Answer» A. hammering a magnet | |
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Explanation: Hammering a rod will either allow it to become slightly magnetic inlaid along a magnetic field (i.e.North - South) or demagnetize it if laid across the field lines (i.e. East-West). A current passing through a coil will produce a magnetic field. |
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| 1129. |
Which among the following is false about work? |
| A. | If displacement is zero, work is zero |
| B. | Work done can be negative |
| C. | It is a vector quantity |
| D. | Its unit is Joule |
| Answer» C. It is a vector quantity | |
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Explanation: Vector, in physics, a quantity that has both magnitude and direction. For example, displacement, velocity, and acceleration are vector quantities, while speed (the magnitude of velocity), time, and mass are scalars. |
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| 1130. |
Which of the following is false? |
| A. | Most carbon compounds are poor conductors of electricity. |
| B. | The force of attraction between carbon molecules is not very strong. |
| C. | The atomic number of carbon is 6. |
| D. | The earth’s crust has about 2% carbon in the form of minerals. |
| Answer» D. The earth’s crust has about 2% carbon in the form of minerals. | |
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Explanation: 0 |
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| 1131. |
Two vectors are said to be equal if – |
| A. | only their magnitudes are same |
| B. | only their directions are same |
| C. | both magnitude and direction are same |
| D. | magnitudes are same but directions are opposite |
| Answer» C. both magnitude and direction are same | |
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Explanation: If the magnitude as well as direction of two vectors are equal, then they are known as equal vectors. In other words, two vectors are said to be equal, if they possess equal magnitude and are headed towards the same direction. For two equal vectors, their directed line segments must be parallel. |
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| 1132. |
A real gas can act as an ideal gas in - |
| A. | high pressure and low temperature |
| B. | low pressure and high temperature |
| C. | high pressure and high temperature |
| D. | low pressure and low temperature |
| Answer» B. low pressure and high temperature | |
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Explanation: Real gases approximate ideal gases when their pressure is relatively low, and their temperature reasonably high. A real gas deviates increasingly from ideality as it is compressed and cooled to near the point at which it will condense into a liquid. |
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| 1133. |
The Dynamo converts – |
| A. | Electrical Energy into Mechanical Energy |
| B. | Mechanical Energy into Magnetic Energy |
| C. | None of these |
| D. | Mechanical Energy into Electrical Energy |
| Answer» D. Mechanical Energy into Electrical Energy | |
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Explanation: Dynamo is a device for converting mechanical energy into electrical energy, especially one that produces direct current. It uses electromagnetic principles to convert mechanical rotation into a pulsing direct electric current through the use of a commutator. |
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| 1134. |
Winch of the following is not true about X-rays? |
| A. | have low penetrating power |
| B. | travel with the speed of light |
| C. | Can be reflected or refracted |
| D. | can affect photographic plates |
| Answer» A. have low penetrating power | |
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Explanation: X-rays and gamma rays are photons, i.e. high-energy light-waves. When emitted by a source, for example, radium or cobalt, located outside the body, they easily pass through the body, hence they are usually called penetrating radiation. Because X-rays are penetrating, they can be used in diagnostic medicine to image human bones or human organs made opaque by a dye. |
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| 1135. |
A Fuse wire is characterized by – |
| A. | High resistance and low melting point |
| B. | High resistance and high melting point |
| C. | Low resistance and high melting point |
| D. | Low resistance and low melting point |
| Answer» D. Low resistance and low melting point | |
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Explanation: A fuse is a type of low resistance resistor that acts as a sacrificial device to provide over current protection, of either the load or source circuit. Low resistance causes the fusewire to melt if a current more than the safe current for the appliance starts flowing through the circuit. |
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| 1136. |
Ice is packed in saw dust because – |
| A. | saw dust will not get melted easily. |
| B. | saw dust is poor conductor of heat. |
| C. | saw dust is a good conductor of heat. |
| D. | saw dust does not stick to the ice. |
| Answer» B. saw dust is poor conductor of heat. | |
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Explanation: ice needs to absorb heat energy to melt and become water (called latent heat of fusion). Since saw-dust is a poor conductor of heat, it takes more time for the ice to absorb the required heat energy. This allows ice to remain in solid state for more time when packed in saw dust. |
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| 1137. |
A stone is dropped from the roof of a house towards the ground. The kinetic energy of the stone will be maximum: |
| A. | just after it is dropped |
| B. | when it is just on the half-way |
| C. | just before it touches the ground |
| D. | when it touches the ground |
| Answer» C. just before it touches the ground | |
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Explanation: When an object reaches the ground it has its maximum value of kinetic energy just before touching the ground. Since kinetic energy + potential energy= Constant; so on reaching ground the potential energy of an object becomes zero (0). The kinetic energy on reaching ground becomes maximum. |
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| 1138. |
What is Hooke’s Law? |
| A. | Stress is inversely proportional to strain. |
| B. | Stress is directly proportional to strain. |
| C. | Stress and strain are dependent on each other. |
| D. | Stress and strain are independent of each other. |
| Answer» B. Stress is directly proportional to strain. | |
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Explanation: Hooke’s law is a principle of physics that states that the force (F) needed to extend or compress a spring by some distance X scales linearly with respect to that distance. |
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| 1139. |
Transfer of heat energy from a heater coil to the cooking vessel takes place through the process of- |
| A. | Convection only |
| B. | Conduction and convection only |
| C. | Radiation and convection only |
| D. | Convection, conduction and radiation |
| Answer» C. Radiation and convection only | |
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Explanation: Conduction is the transfer of heat energy by direct contact, convection is the movement of heat by actual motion of matter; radiation is the transfer of energy with the help of electromagnetic waves. |
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| 1140. |
A drop of liquid assumes spherical shape because: |
| A. | Intermolecular forces are strong in liquids |
| B. | A sphere has the least surface area for a given volume |
| C. | A sphere has the largest surface area for a given volume |
| D. | Inter molecular forces are weak in liquids |
| Answer» B. A sphere has the least surface area for a given volume | |
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Explanation: A drop of liquid assumes spherical shape because a sphere has the least surface area for a given volume. |
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| 1141. |
What are audible sound waves? |
| A. | Having frequency less than 20 Hz |
| B. | Having frequency between 20 Hz to 20000 Hz |
| C. | Having frequency more than 20000 Hz |
| D. | None of above |
| Answer» B. Having frequency between 20 Hz to 20000 Hz | |
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Explanation: 0 |
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| 1142. |
Sun appears red in colour at sun-rise and sunset due to – |
| A. | the fact that sun emits only red colour at that time |
| B. | red light having longer wave length scatters away |
| C. | that sun Comes out of the mountains |
| D. | that all other colours scatter away except red |
| Answer» D. that all other colours scatter away except red | |
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Explanation: According to Rayleigh's law, the intensity of scattered light varies inversely as the fourth power of its wavelength. Sunlight consists of seven colours. Of these, red has the maximum wavelength. During sunrise and sunset, the rays have to travel a larger part of the atmosphere because they are very close to the horizon. |
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| 1143. |
Why does a cannon recoil after firing? |
| A. | Conservation of energy |
| B. | Backward thrust of gases produced |
| C. | NeMon's third law of motion |
| D. | Newton's first law of motion |
| Answer» C. NeMon's third law of motion | |
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Explanation: Recoil is the backward momentum of a gun when it is discharged. In technical terms, the recoil caused by the gun exactly balances the forward momentum of the projectile and exhaust gases (ejecta), According to Newton's third law. In case of canons, the momentum is transferred to the ground through its mount. |
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| 1144. |
During the motion of a projectile fired from the earth surface, . |
| A. | its kinetic energy remains constant |
| B. | its momentum remains constant |
| C. | vertical component of its velocity remains constant |
| D. | horizontal component of its velocity remains constant |
| Answer» D. horizontal component of its velocity remains constant | |
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Explanation: The motion of a projectile is a two-dimensional motion—Horizontal motionand vertical motion—that take place independent of each other. The horizontal velocity of a projectile is constant (a never changing in value). The force of gravity continuously affects the vertical component, so the vertical motion is a uniformly accelerated motion. |
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| 1145. |
A system exhibiting S.H.M. must possess – |
| A. | Elasticity as well as inertia |
| B. | Elasticity, inertia and an external force |
| C. | Elasticity only |
| D. | Inertia only |
| Answer» A. Elasticity as well as inertia | |
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Explanation: Basic conditions to execute simple harmonic motion are: (i) There must be an elastic restoring force acting on the system, (ii) the system must have inertia, and (iii) the acceleration of the system should be directly proportional to its displacement and is always directed to mean position. |
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| 1146. |
The ringing of an electric bell in an enclosed evacuated glass bell jar is not heard outside because - |
| A. | the ringing is not loud enough |
| B. | the glass of the bell jar absorbs the sound waves |
| C. | the bell jar is too small |
| D. | there is no air or any other gas in the bell jar |
| Answer» D. there is no air or any other gas in the bell jar | |
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Explanation: 0 |
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| 1147. |
At hill stations, the boiling point of water will be – |
| A. | same as at sea level |
| B. | less than that at sea level |
| C. | more than that at sea level |
| D. | equal to the melting point of ice |
| Answer» B. less than that at sea level | |
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Explanation: The boiling point is the temperature at which the vapour pressure of theliquid equals the environmental pressure surrounding the liquid. Atmospheric pressure is due to air above any given point. The atmospheric pressure at high altitudes like hill station is less than at the sea level. |
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| 1148. |
Indicate the correct arrangement for electromagnetic radiation in order of their increasing wavelength. |
| A. | Microwave, infrared, visible. X-rays |
| B. | X-rays, visible, infrared, microwave |
| C. | Visible, infrared, microwave, X-rays |
| D. | X-rays, infrared, visible, microwave |
| Answer» D. X-rays, infrared, visible, microwave | |
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Explanation: The Electromagnetic spectrum in order of decreasing energy, thus increasing wavelength : Gamma Rays-wavelength: 0.01 nm; X-rays -1 nm ; Ultra-violet Rays-0.1 micrometres ; Visible Light-Red light : 0.7 micrometres, Violet Light : 0.4 micrometres ; Infrared Radiation-0.01 mm ; Microwaves -less than 10 cm, usually lem ; Radiowaves- Long, Medium and Short Waves : 1am-10 m ; and Very High Frequency (VHF) and Ultra High Frequency (UHF): 10 m-10 cm. |
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| 1149. |
A black body can absorb radiations of |
| A. | lower wavelengths only |
| B. | intermediate wavelengths only |
| C. | higher wavelengths only |
| D. | all wavelengths |
| Answer» D. all wavelengths | |
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Explanation: A black body is a theoretical object that absorbs 100% of the radiation that hits it. Therefore it reflects no radiation and appears perfectly black. At a particular temperature the black body would emit the maximum amount of energy possible for that temperature. This value is known as the black body radiation. It would emit at every wavelength of light as it must be able to absorb every wavelength to be sure of absorbing all incoming radiation. |
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| 1150. |
The water from a hand pump is warm in winter because – |
| A. | Our body is cold in winter and the water appears to be warm |
| B. | The temperature inside the earth is higher than the atmospheric temperature |
| C. | The pumping process causes friction which warms up the water |
| D. | Inside water comes out and absorbs heat from the environment |
| Answer» B. The temperature inside the earth is higher than the atmospheric temperature | |
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Explanation: In winter, the outside temperature is lower than that of water flowing out of the pump, and therefore, the water is warm. Whereas in summer, the outside temperature is higher than the water of the pump, and therefore, it feels cold. |
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