McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: General Knowledge (GK) .
| 401. |
The light rays used for eliminating bacteria – |
| A. | X-rays |
| B. | infrared rays |
| C. | microwave radiation |
| D. | ultra-violet radiation |
| Answer» D. ultra-violet radiation | |
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Explanation: Ultraviolet radiation is used to kill microorganisms, molds and fungus in various environmental applications. UV sterilization is used for air-purification systems, water purification, aquarium and pond maintenance, laboratory hygiene and food and beverage protection. |
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| 402. |
The audio signals of TV are – |
| A. | Amplitude modulated |
| B. | Frequency modulated |
| C. | Unmodulated |
| D. | Velocity modulated |
| Answer» B. Frequency modulated | |
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Explanation: In analogue television, the sound portion of a broadcast is invariably modulated separately from the video. Most commonly, the audio and video are combined at the transmitter before being presented to the antenna, but in some cases separate aural and visual antennas can be used. In almost all cases, standard wideband frequency modulation is used. |
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| 403. |
Red light is used for signals because it has – |
| A. | long wavelength |
| B. | high intensity |
| C. | high frequency |
| D. | low refraction in the medium |
| Answer» A. long wavelength | |
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Explanation: Red is the international colour of stop signs and stop lights on highways and intersections because it is scattered the least by air molecules. The effect of scattering is inversely related to the fourth power of the wavelength of a colour. Red has the highest wavelength of all the colours and is able to travel the longest distance through fog, rain, and the alike. |
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| 404. |
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 on medium sized centrifuges that put an object in rotation around a fixed axis, applying force perpendicular to the axis. |
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| 405. |
Which zone of a candle flame is the hottest? |
| A. | Dark innermost zone |
| B. | Outermost zone |
| C. | Middle luminous zone |
| D. | Central zone |
| Answer» C. Middle luminous zone | |
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Explanation: The outermost zone of the flame is blue in colour and it is the hottest part. The innermost zone is the least hot and black in colour. |
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| 406. |
'Hydraulic brakes' work on the principle of – |
| A. | Pascal's law |
| B. | Thomson's law |
| C. | Newton's law |
| D. | Bernoulli's theorem |
| Answer» A. Pascal's law | |
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Explanation: Pascal's law states that when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container. According to Pascal's principle, in a hydraulic system a pressure exerted on a piston produces an equal increase in pressure on another piston in the system. |
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| 407. |
The instrument for measuring intensity of earthquakes is called – |
| A. | Ediograph |
| B. | Pantagraph |
| C. | Ergograph |
| D. | Seismograph |
| Answer» D. Seismograph | |
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Explanation: Seismometers are instrument that measures motion of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions and other seismic sources. Records of seismic waves allow seismologists to map the interior of the earth and locate and measure the size of these different sources. Seismograph is another Greek term meaning to draw siesmo waves. |
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| 408. |
Which one of the following animals can hear ultrasonic sound? |
| A. | Rat |
| B. | Squirrel |
| C. | Cat |
| D. | Bat |
| Answer» D. Bat | |
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Explanation: Ultrasound is a cyclic sound pressure wave with a frequency greater than the upper limit of the human hearing range. Ultrasound is thus not separated from "normal" (audible) sound based on differences in physical properties, only the fact that humans cannot hear it. |
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| 409. |
‘Therm' is the unit of – |
| A. | Power |
| B. | Heat |
| C. | Light |
| D. | Distance |
| Answer» B. Heat | |
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Explanation: Therm is a non-SI unit of heat energy equal to 100,000 British thermal units (BTU). It is approximately the enemy equivalent of burning 100 cubic feet (often referred to as 1 CCF) of natural gas. Since (Natural Gas) meters measure volume and not energy content, a therm factor is used by (Natural) gas companies to convert the volume of gas used to its heat equivalent, and thus calculate the actual energy use. |
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| 410. |
Newton's first law of motion gives the concept of – |
| A. | Energy |
| B. | Work |
| C. | Momentum |
| D. | Inertia |
| Answer» D. Inertia | |
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Explanation: Newton's laws of motion are three physical laws that form the basis for classical mechanics. They describe the relationship between the forces acting on a body and its motion due to those forces. The first law states that if the net force (the vector sum of all forces acting on an object) is zero, then the velocity of the object is constant. Newton's first law is often referred to as the law of inertia. |
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| 411. |
When heated from 0° to 10°C volume of a given mass of water will - |
| A. | Increase gradually |
| B. | Decrease gradually |
| C. | Increase and after will decrease |
| D. | Decrease and after will increase |
| Answer» D. Decrease and after will increase | |
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Explanation: 0 |
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| 412. |
Which of the following is an ex-ample for cantilever beam? |
| A. | Diving board |
| B. | Bridge |
| C. | See-saw |
| D. | Common balance |
| Answer» B. Bridge | |
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Explanation: A cantilever is a beam anchored at only one end. The beam carries the load to the support where it is resisted by moment and shear stress. Cantilever construction allows for overhanging structures without external bracing. Cantilevers can also be constructed with trusses or slabs. This is in contrast to a simply supported beam such as those found in a post and lintel system. A simply supported beam is supported at both ends with loads applied between the supports. Cantilevers are widely found in construction, notably in cantilever bridges. |
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| 413. |
It is difficult to cook rice – |
| A. | at the top of a mountain |
| B. | at the sea level |
| C. | under a mine |
| D. | same anywhere |
| Answer» A. at the top of a mountain | |
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Explanation: On a mountain top the air pressure is a little lower. At higher elevations, water boils at a little lower temp than 100 degrees C. On a mountain top cooking takes longer, because it is like cooking on medium heat, instead of leaving the burner on high. Either way it will cook, one will take longer than the other. The boiling point |
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| 414. |
Angle of friction and angle of repose are |
| A. | Equal to each other |
| B. | Not equal to each other |
| C. | Proportional to each other |
| D. | None of the above |
| Answer» A. Equal to each other | |
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Explanation: The angle of repose or the critical angle of repose, of a granular material is the steepest angle of descent or dip of the slope relative to the horizontal plane when material on the slope face is on the verge of sliding. This angle is in the range 0°-90° .when bulk granular materials are poured onto a horizontal surface, a conical pile will form. The internal angle between the surface of the pile and the horizontal surface is known as the angle of repose and is related to the density, surface area and shapes of the particles, and the coefficient of friction of the material. |
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| 415. |
If a boy sitting in a train, which is moving at a constant velocity, throws a ball straight up into the air, the ball will – |
| A. | Fall in front of him |
| B. | Fall behind him |
| C. | Fall into his hand |
| D. | None of the above |
| Answer» C. Fall into his hand | |
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Explanation: If a person throws a ball vertically upwards in a moving train, it comes hack to his hand. The moment the ball was thrown, the ball was also in motion alone with the person who had thrown the ball and the train. This is due to inertia of motion. So when the ball remains in the air, both the person and the ball move ahead by the same distance. This makes the ball to come back to his hand on its return. |
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| 416. |
A metal plate with a circular hole at the centre is heated. What will happen to the area of the hole? |
| A. | Increase |
| B. | Decrease |
| C. | Remain constant |
| D. | Will increase first and then decrease |
| Answer» A. Increase | |
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Explanation: Assuming the disc is uniform and isotropic (the same in different directions), the hole will expand in the same ratio as the metal. It is because the thermal expansion equation applies to all lengths associated with the metal, including the circumference of the hole, since the edge of the hole is made out of metal. And if the circumference of the hole expands, so does the diameter. |
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| 417. |
Stars in the sky appear to twinkle due to – |
| A. | a series of refractions |
| B. | a series of reflections |
| C. | a surface tension phenomenon |
| D. | multiple diminishing brightness |
| Answer» A. a series of refractions | |
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Explanation: The movement of air (sometimes called turbulence) in the atmosphere of Earth causes a series of refractions which makes the starlight to get slightly bent as it travels from the distant star through the atmosphere down to us on the ground. This means that some of the light reaches us directly and some gets bent slightly away. To our eyes, this makes the star seem to twinkle. |
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| 418. |
A pilot has to release the bomb to hit a target – |
| A. | right above the target |
| B. | beyond the target |
| C. | before the target |
| D. | None of these |
| Answer» C. before the target | |
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Explanation: According to Newton's first law, an object that is at rest will stay at rest unless an unbalanced force acts upon it and an object that is in motion will not change its velocity unless an unbalanced force acts upon it. |
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| 419. |
Parabolic mirros are used in – |
| A. | Car headlights |
| B. | Driving mirrors |
| C. | Dentists mirros |
| D. | Shaving mirros |
| Answer» A. Car headlights | |
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Explanation: A parabolic reflector (mirror) transforms an incoming plane wave traveling along the axis into a spherical wave converging toward the focus. Since the principles of reflection are reversible, parabolic reflectors can also be used to project energy of a source at its focus outward in a parallel beam, used in devices such as spotlights and car headlights. |
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| 420. |
Which atmospheric layer contains ozone layer? |
| A. | Genosphere |
| B. | Zonosphere |
| C. | Stratosphere |
| D. | Ionosphere |
| Answer» C. Stratosphere | |
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Explanation: The ozone layer is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet (UV) radioation. |
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| 421. |
Water flows through a horizontal pipe at a constant volumetric rate. At a location where the cross sectional area decreases, the velocity of the fluid: |
| A. | increases |
| B. | decreases |
| C. | stays the same |
| D. | none of the above |
| Answer» A. increases | |
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Explanation: 0 |
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| 422. |
Which of the following is the best conductor of Electricity? |
| A. | Ordinary water |
| B. | Sea water |
| C. | Boiled water |
| D. | Distilled water |
| Answer» B. Sea water | |
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Explanation: It sounds crazy, but it's true! This is because Sea water has Salt that is a good conductor of electricity. Salt molecules are made of sodium ions and chlorine ions. |
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| 423. |
Rate of change of momentum is - |
| A. | Area |
| B. | Pressure |
| C. | Force |
| D. | Velocity |
| Answer» C. Force | |
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Explanation: According to Newton’s Second Law of motion, the rate of change of momentum of an object is directly proportional to the resultant force applied and is in the direction of the resultant force. |
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| 424. |
An ice block with a piece of lead embedded in it floats in water. If ice melts the water level – |
| A. | Rises |
| B. | Falls |
| C. | Remains same |
| D. | Falls first and them rises |
| Answer» B. Falls | |
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Explanation: 0 |
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| 425. |
A particle dropped from the top of a tower uniformly falls on ground at a distance which is equal to the height of tower. Which of the following paths will be traversed by the particle? |
| A. | Circle |
| B. | Parabolic |
| C. | Great circle |
| D. | Hyper-parabolic |
| Answer» B. Parabolic | |
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Explanation: If a particle dropped from the top of a tower uniformly falls on ground at a distance which is equal to the height of tower then a parabolic path will be traversed by a particle because when the particle is dropped that point is called the point of projection and when it reaches the ground that point is called the point of impact. |
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| 426. |
The frequency of ultrasound wave is typically – |
| A. | Above 20 kHz |
| B. | Above 20,000 kHz |
| C. | Below 20 kHz |
| D. | Below 02 kHz |
| Answer» C. Below 20 kHz | |
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Explanation: Ultrasound is a cyclic sound pressure wave with a frequency greater than the upper limit of the human hearing range. Ultrasound is thus not separated from "normal" (audible) sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is approximately 20 kilohertz (20,000 hertz) in healthy, young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz. |
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| 427. |
Intensity of gravitational field of earth is maximum at – |
| A. | Poles |
| B. | Equator |
| C. | Centre of earth |
| D. | Surface |
| Answer» A. Poles | |
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Explanation: perfect sphere of spherically uniform density (density varies solely with distance from centre) would produce a gravitational field of uniform magnitude at all points on its surface. always pointing directly towards the sphere's centre. However, the Earth deviates slightly from this ideal, and there are consequently slight deviations in both the magnitude and direction of gravity across its surface. |
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| 428. |
The spokes used in the wheel of a bicycle increase its – |
| A. | Moment of inertia |
| B. | Velocity |
| C. | Acceleration |
| D. | Momentum |
| Answer» A. Moment of inertia | |
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Explanation: A spoke is one of some number of rods radiating from the center of a wheel (the hub where the axle connects), connecting the hub with the round traction surface. Since bicycle and wheelchair wheel spokes are only in tension, flexible and strong materials such as synthetic fibers, are also occasionally used. Metal spokes used in bicycles also increase the moment of inertia. |
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| 429. |
A soap bubble shows colours when illuminated with white light. This is due to – |
| A. | Diffraction |
| B. | Polarization |
| C. | Interference |
| D. | Reflection |
| Answer» C. Interference | |
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Explanation: The iridescent colours of soap bubbles are caused by interfering of (internally and externally) reflected light waves and are determined by the thickness of the film. This phenomenon is not the same as the origin of rainbow colours (caused by the refraction of internally reflected light), but rather are the same as the phenomenon causing the colours in an oil slick on a wet road. |
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| 430. |
A boy sitting in an open car moving with the constant speed throws a ball straight up into the air. |
| A. | The ball falls – |
| B. | Behind him |
| C. | In front of him |
| D. | Into his hand |
| Answer» A. The ball falls – | |
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Explanation: The moment ball is thrown, it is moving with the velocity of the car. According to the inertia of motion it will continue to move in the same direction with the same velocity. As the ball is moving up and the down it will maintain its forward motion but practically it is not possible to neglect the resistance caused by air friction. So, the ball will fall behind him. |
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| 431. |
The process involved in making soap is |
| A. | Saponification |
| B. | Hydrolysis |
| C. | Condensation |
| D. | Polymerization |
| Answer» A. Saponification | |
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Explanation: Saponification is a process that produces soap, usually from fats and lye. In technical teens, saponification involves base (usually caustic soda NaOH) hydrolysis of triglycerides, which are esters of fatty acids, to form the sodium salt of a carboxylate. In addition to soap, such traditional saponification processes produces glycerol. |
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| 432. |
A pond of water appears less deep due to – |
| A. | Reflection |
| B. | Diffraction |
| C. | Refraction |
| D. | Polarization |
| Answer» C. Refraction | |
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Explanation: The apparent depth will look less that its real depth due to the refraction of light. First of all, imagine an object at the bottom of the pond, emitting three beams of light: one straight to the centre of your eye, one above your eye, and one below. Now, as light travels faster in air than it does in water, it will accelerate as it breaks the surface, at which point it bends away from the 'normal' - the imaginary line perpendicular to the surface. So back to those three beams, the one coming straight at your eye, and as such perfectly vertical, will not bend one way or another as it leaves the water. |
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| 433. |
The oldest type of energy known to man is – |
| A. | Wind power |
| B. | Solar power |
| C. | Tidal energy |
| D. | Geothermal energy |
| Answer» D. Geothermal energy | |
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Explanation: The oldest energy known to man is Geothermal energy. This geothermal energy originates from the original formation of the planet, from radioactive decay of minerals, and from solar energy absorbed at the surface. It has been used for space heating and bathing since ancient Roman times, but is now better known for generating electricity. Geothermal energy is thermal energy generated and stored in the Earth. |
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| 434. |
The source of the sun's energy is the process of – |
| A. | Photoelectric emission |
| B. | Nuclear fission |
| C. | Nuclear fusion |
| D. | Thermionic emission |
| Answer» C. Nuclear fusion | |
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Explanation: The Sun formed about 4.6 billion years ago from the gravitational collapse of a region within a large molecular cloud. Most of the matter gathered in the center, while the rest flattened into an orbiting disk that would become the Solar System. The central mass became increasingly hot and dense, eventually initiating thermonuclear fusion in its core. It is thought that almost all other stars form by this process. |
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| 435. |
A multimeter is used to measure – |
| A. | current |
| B. | voltage |
| C. | resistance |
| D. | All of the above |
| Answer» D. All of the above | |
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Explanation: A multimeter or a multitester, also known as a VOM (Volt-Ohm meter), is anelectronic measuring instrument that combines several measurement functions in one unit. A typical multimeter may include features such as the ability to measure voltage, current and resistance. Multimeters may use analog or digital circuits—analog multimeters (AMM) and digital multimeters (often abbreviated DMM or DVOM.) |
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| 436. |
In the atmosphere ultraviolet rays are absorbed by – |
| A. | Oxygen |
| B. | Nitrogen |
| C. | Ozone |
| D. | Helium |
| Answer» A. Oxygen | |
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Explanation: Most of the ultraviolet radiation in sunlight is absorbed by oxygen in Earth's atmosphere, which forms the ozone layer of the lower stratosphere. UV light is found in sunlight (where it constitutes about 10% of the energy in vacuum) and is emitted by electric arcs and specialized lights such as black lights. It can cause chemical reactions, and causes many substances to glow or fluoresce. Most ultraviolet is classified as non-ionizing radiation. |
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| 437. |
Which of the following metals is used for the manufacture of heating elements provided in electric iron? |
| A. | Nickel |
| B. | Chromium |
| C. | Nichrome |
| D. | Tungsten |
| Answer» C. Nichrome | |
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Explanation: Nichrome is the most common domestic heating element and is found in many household products. Commonly, items such as toasters, hair dryers and heaters use nichrome coils to pass electricity and give off heat. Nichrome is made of 80 percent nickel and 20 percent chromium, and its high melting point of 1,400 degrees Celsius. |
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| 438. |
When a bottle of scent is kept open in a corner of a room its odour is felt in all parts of the room. This is clue to the phenomenon of – |
| A. | evaporation |
| B. | vaporisation |
| C. | diffusion |
| D. | sublimation |
| Answer» C. diffusion | |
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Explanation: Diffusion is one of several transport phenomena that occur in nature. A distinguishing feature of diffusion is that it results in mixing or mass transport without requiring bulk motion. Thus, diffusion should not be confused with convection or advection, which are other transport mechanisms that use bulk motion to move particles from One place to another. |
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| 439. |
Clear nights are colder than cloudy nights because of – |
| A. | conduction |
| B. | condensation |
| C. | radiation |
| D. | insolation |
| Answer» C. radiation | |
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Explanation: Cloudless nights are colder because the nights that have clouds provide a blanket for the earth and trap some of the hot day air where as the cloudless nights have no protection so all the hot air rises up into the sky. radiation is a process in which energetic particles or energetic waves travel through vacuum, or through matter-containing media that are not required for their propagation. |
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| 440. |
In AC circuits, AC meters measure – |
| A. | mean values |
| B. | rms values |
| C. | peak values |
| D. | mean square values |
| Answer» B. rms values | |
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Explanation: Voltages and currents for AC circuits are generally expressed as rms (root mean square) values. For a sine wave, the relationship between the peak and the rms average is: rms value = 0.707 peak value. |
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| 441. |
When a light wave is reflected from a mirror, there is a change in its – |
| A. | frequency |
| B. | amplitude |
| C. | wavelength |
| D. | velocity |
| Answer» B. amplitude | |
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Explanation: When a light wave is reflected from an object, it changes not only its amplitude but also its phase according to the properties of the object at a particular point. The velocity and momentum are just reversed in another direction. |
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| 442. |
A body absorbs heat most if it is – |
| A. | black and rough |
| B. | black and smooth |
| C. | white and rough |
| D. | white and smooth |
| Answer» A. black and rough | |
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Explanation: A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. Another property is roughness. Sand is rough and black and so it is a good absorber. |
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| 443. |
Which of the following is not a vector quantity? |
| A. | Acceleration |
| B. | Electric current |
| C. | Force |
| D. | Velocity |
| Answer» B. Electric current | |
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Explanation: For a physical quantity to be termed a vector quantity, having magnitude and direction is not enough. |
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| 444. |
Which one of the following is used for determining the structure of crystal - |
| A. | Gamma rays |
| B. | X-rays |
| C. | UV rays |
| D. | visible light |
| Answer» B. X-rays | |
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Explanation: Crystallography is the science that examines crystals which can be found everywhere in nature, from salt to snowflakes to gemstones. |
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| 445. |
How many terminals do an electric cell has? |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» B. 2 | |
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Explanation: The metal disc is the negative terminal. All electric cells have two terminals; a positive terminal and a negative terminal. |
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| 446. |
Water from soil enters into the root hairs owing to : |
| A. | Atmospheric pressure |
| B. | Capillary pressure |
| C. | Root pressure |
| D. | Osmotic pressure |
| Answer» B. Capillary pressure | |
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Explanation: In plants, the transpiration stream is the uninterrupted stream of water, and other, which is taken up by the roots and, via the xylem vessels, transported to the leaves where it will eventually evaporate into the airiapoplast- interface of the substomatal cavity. It is driven in by capillary action and in some plants root pressure. The main driving factor is the difference in water potential between the soil and the substomatal cavity caused by transpiration. |
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| 447. |
The unit of electrical power is – |
| A. | Bolt |
| B. | Watt |
| C. | Kilowatt hour |
| D. | Ampere |
| Answer» B. Watt | |
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Explanation: Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. Watt is named after the Scottish engineer James Watt who invented the Newcomen Steam Engine. |
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| 448. |
The scientist who first sent electromagnetic waves to distant places is – |
| A. | James Clerk Maxwell |
| B. | Heinrich Hertz |
| C. | Thomas Alva Edison |
| D. | John Logie Baird |
| Answer» C. Thomas Alva Edison | |
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Explanation: Radio is the transmission of single through free space by electromagnetic radiation of a frequency significantly below that of visible light, in the radio frequency range, from about 30 kHz to 300 GHz. Those waves are called radio waves. |
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| 449. |
Conversion of chemical energy into electrical energy occurs in – |
| A. | atomic bombs |
| B. | dynamo |
| C. | a battery |
| D. | electric heaters |
| Answer» C. a battery | |
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Explanation: Conversion of chemical energy into electrical energy occurs in battery. |
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| 450. |
Damp clothes are dried in spin dryers by the action of – |
| A. | centripetal forces |
| B. | centrifugal forces |
| C. | central forces |
| D. | non central forces |
| Answer» B. centrifugal forces | |
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Explanation: The spin dryer is probably the most familiar centrifuge. The spin dryer of a washing machine removes excess water from the clothing by rotating at a high speed. The high speed of rotation creates a high centrifugal force for the water in the clothing which causes it to be pulled to the outside of the spinning portion of the washing machine and away from the clothes. |
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