Explanation: C. As fuse is a safety device used in domestic slectric circuit to prevent the house from short circuit. The fuse wire is made up of the metal having low melting point.

Explanation: A. When electric current passes through the metal wire, the wire becomes hot and produces heat. It is due to heating effect of current, which is obtained by transformation of electrical energy into heat energy when the current passes through the wire, the collision of the free electrons with ions or metal atoms collide with each other which releases energy.

Explanation: C. As fuse is a safety device used in domestic slectric circuit to prevent the house from short circuit. The fuse wire is made up of the metal having low melting point.

Explanation: A. When electric current passes through the metal wire, the wire becomes hot and produces heat. It is due to heating effect of current, which is obtained by transformation of electrical energy into heat energy when the current passes through the wire, the collision of the free electrons with ions or metal atoms collide with each other which releases energy.

1. Radial tyres
2. Streamlined body
3. Multipoint fuel injection
4. Catalytic converter with exhaust

Which of these features make the newer models of motor cars more fuel efficient?

Explanation: A. A streamlined design is one in which objects that move through a gas or liquid are shaped to match these lines, and therefore, reduce the energy required to produce that motion. Multi point fuel injection system injects fuel into individual cylinders, based on commands from the on board engine management system computer-popularly known as the engine control unit/ECU. These techniques result not only in better power balance amongst the cylinders but also in higher output from each one of them, along with faster throttle response. The other two options radial tyres and catalytic converter with exhaust do not contribute to make the car more fuel efficient.

Explanation: B. First statement can be explained on the laws of motion. First statement involves the use of Newton

Explanation: D. The decibel is widely known as a measure of sound pressure level, but is also used for a wide variety of other measurements in science and engineering. The decibel is commonly used in acoustics to quantify sound levels relative to a 0 dB reference which has been defined as a sound pressure level of 0.0002 microbar. The noise level of decibel would corresponds to noise from machine shop.

Explanation: A. Both the statements are correct and statement 2 is also correct explanation for statement 1. 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. If the refractive index is lower on the other side of the boundary, no light can pass through and all of the light Is reflected. Thus because of this phenomena traffic light beads glow when light falls on them.

Explanation: C. Mass is a universal constant. The mass of a body remains unchanged in any part of universe. Mass of a body does not change with respect to gravity. It is the weight that changes with gravity.

1. the acceleration is zero when the bob passes through the mean position.
2. in each cycle the bob attains a given velocity twice.
3. both acceleration and velocity of the bob are zero when it reaches its extreme position during the oscillation.
4. the amplitude of oscillation of the simple pendulum decreases with time.

Which of these statements are correct?

Explanation: C. statement 3 is not correct.

Explanation: D. Figure (d) correctly represents the time-distance graph for one dimensional uniform motion

Explanation: B. 10 ohm.

1. more neutrons are released in each of the fission reactions.
2. the neutrons immediately take part in the fission process.
3. the fast neutrons are slowed down by graphite.
4. every neutron released in the fission reaction initiates further fission.

Which of these statements are correct?

Explanation: A. A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. The most common use of nuclear reactors is for the generation of electrical power and for the power in some ships. In every fission reaction in which uranium nuclei splits up to give smaller nuclei three more neutrons are produced which further results into splitting of heavy uranium nuclei and more number of neutrons will be produced. Thus, statement, 1 and 2 are correct. In nuclear reactor all the neutrons produced cannot take part in fission reaction, else reaction can turn out extremely violent. Thus, graphite rods are used as a control rods to slow down the speed of fast moving neutrons. Thus, statement 3 is also correct.

Explanation: B. Dust particles are responsible for the diffusion of light in atmosphere.

Explanation: C. The velocity of sound in air is determined by the air itself and is not dependent upon the amplitude, frequency, or wavelength of the sound. The velocity of sound c depends on the temperature of air and not on the air pressure. Thus, velocity of sound in air increases with temperature and remains unaffected with increase of pressure. Therefore, statements 1, 2 and 4 are right. Only statement 3 is wrong. The only other factor that has any effect on the speed of sound in air is the amount of humidity in the air. An increase in the amount of humidity in the air increases the speed by a small amount.

Explanation: D. An alternating current (a.c.) is one which is constantly changing direction. Alternating current have two cycles positive half cycle and negative half cycle. Mains electricity is an a.c. supply which is supplied to homes in India at 220 V AC at 50 Hz. Thus, in our houses the current in A.C. electricity line changes direction = 50

Explanation: B. Density of gold is 19.30 g/cm3. The density of ultra pure liquid mercury is 13.534 g/cm3 and the density of steel is 7.80 g/cm3.

Explanation: B. Human body has different resistance when human body dry then the resistance is 105 ohms, and when human body wet because of water or sweet then the resistance is 1000 ohms, so for dry skin the resistance is 104 ohms. Hence option (B) is correct.

1. Liquefied natural gas (LNG) is liquefied under extremely cold temperatures and high pressure to facilitate storage or transportation in specially designed vessels.
2. First LNG terminal in India was built in Hassan.
3. Natural gas liquids (NGL) are separated from LPG and these include ethane, propane, butane and natural gasoline.

Which of the statements given above is/are correct?

Explanation: B. Liquified Natural Gas or LNG is natural gas (predominantly methane, CH4) that has been converted temporarily to liquid form for ease of storage or transport. The liquefaction process involves removal of certain components, such as dust, acid gases, helium, water, and heavy hydrocarbons, which could cause difficulty downstream. The natural gas is then condensed into a liquid maximum transport pressure set at around 25 kPa/3.6 psi by cooling it to approximately

Explanation: D. Varieties of LPG bought and sold include mixes that are primarily propane and butane, the common, mixes include propane (60%) and butane (40%), depending on the season in winter more propane, in summer more butane. Propylene and butylenes are usually also present in small concentration. A powerful odorant, ethane thiol, is added so that leaks can be detected easily. Methane is a chemical compound with the chemical formula (CH4). Compared to other hydrocarbon fuels, burning methane produces less carbon dioxide for each unit of heat released. In many cities, methane is piped into homes for domestic heating and cooking purposes. Methane in the form of compressed natural gas is used as a vehicle fuel. Methane is used in industrial chemical processes for the production of hydrogen, methanol, acetic acid, and acetic anhydride, also used as a fuel in factories.

Explanation: D. The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20

Explanation: C. fluorescent lamp or fluorescent tube is a gas discharge lamp that uses electricity to excite mercury vapour. The excited mercury atoms produce shortwave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. 6500 K is usually printed on a used fluorescent tubelight.

Explanation: C. Dolby B and C are the noise reduction circuits developed by Dolby laboratories. Dolby noise reduction has made it possible to protect the music from tape noise, and helped make cassette the most popular audio product ever devised.

Explanation: C. Correct option is C.

Explanation: D. Viscocity of Kerosene is least among all, so it will emptied first.

1. If magenta and yellow coloured circles intersect, the intersected area will have red colour.
2. If cyan and magenta coloured circles intersect, the intersected area will have blue colour.

Which of the statements given above is/are correct?

Explanation: C. Combination of red and blue colour results into formation of magenta colour. Whereas combination of red and green colour results in to formation of yellow colour. Thus on combination of magenta and yellow colour red colour will be highlighted. On the other side combination of blue and green results into formation of cyan colour. Combination of red and blue colour produce magenta colour. Therefore, on combination of cyan and magenta colours blue colour will be more highlighted.

1. A flute of smaller length produces waves of lower frequency.
2. Sound travels in rocks in the form of longitudinal elastic waves only.

Which of the statements given above is/are correct?

Explanation: D. The flute is a musical instrument of the woodwind family. A flute of smaller length produces waves of higher frequency. Sound waves travels through medium rocks in the form of longitudinal as well as transverse waves.

Explanation: D. Mach number, a useful quantity in aerodynamics, is the ratio of air speed to the local speed of sound. The speed of sound varies with temperature. Since temperature and sound velocity normally decrease with increasing altitude, sound is refracted upward. Mach number is a function of temperature at altitude. With decrease in sound velocity Mach number increases.

Explanation: D. Radio waves are a type of electromagnetic radiation.

Codes:

Explanation: D. Statement 1 is false. The temperature dependence of liquid viscosity is the phenomenon by which liquid viscosity tends to decrease (or, alternatively, its fluidity tends to increase) as its temperature increases. Thus, with increase of temperature viscosity of glycerine decrease. Statement 2 is correct because with the rise of temperature in case of liquid, the kinetic energy increases as kinetic energy of liquid molecules is directly proportional to absolute temperature.

Codes:

Explanation: C. Statement 1 is true but statement 2 is false. Specific gravity is the ratio of the density (mass of a unit volume) of a substance to the density (mass of the same unit volume) of a reference substance. Mercury has a specific gravity of 13.56 whereas specific gravity of iron is 7.21.Thus, iron ball floats on mercury.

Explanation: B. Correct option is B.

1. Light of longer wavelength are scattered much more than the light of shorter wavelength.
2. The speed of visible light in water is 0.95 times the speed in vacuum.
3. Radio waves are produced by rapidly oscillating electrical currents.
4. To detect the over speeding vehicles, police use the Doppler effect of reflected short radio waves.

Which of these statements are correct?

Explanation: D. Radio waves are a form of electromagnetic radiation, created whenever a charged object (in normal radio transmission, an electron) accelerates with a frequency that lies in the radio frequency (RF) portion of the electromagnetic spectrum. Thus statement 3 is correct. The Doppler's Effect shows a change in a wave's frequency received when it is either reflected from a moving object or generated on a moving object. Police radar speed detectors bounce a radio frequency wave off cars and use their internal electronics to determine the speed at which the object is moving by that frequency change. Therefore, statement 4 is also correct.

1. Terrestrial heating
2. Reflection of light
3. Refraction of light
4. Diffraction of light

Due to which of these phenomena is a mirage formed?

Explanation: C. Convection currents of hot air rising off a surface have a lower density than the air directly above it. The difference in density cause light passing through the air to refract differently, which causes the formation of mirage.

1. it would be difficult to use a kerosene lamp
2. one would not be able to use a straw to consume a soft drink
3. the blotting paper would fail to function
4. the big trees that we see around would not have grown on the Earth

Which of the statements given above are correct?

Explanation: B. Statement 1, 3 and 4 are correct.

Explanation: A. Earth's magnetic field diverts them towards its poles.

Explanation: C. Ball bearings are used to reduce friction and friction is directly proportional to effective surface area. So if effective surface area is reduced then friction will also reduce.

1. Size of the sun at dusk.
2. Colour of the sun at dawn
3. Moon being visible at dawn
4. Twinkle of stars in the sky

Which of the above are optical illusions?

Explanation: C. Size of the Sun at dusk is an optical illusion because of atmospheric refraction. Colour of the sun appears yellow due to scattering whereas pure sunlight is white in colour. Twinkling of stars is an optical illusion. Air whirlpools make the stars twinkle.

1. Dispersion
2. Refraction
3. Internal reflection

Select the correct answer using the codes below.

Explanation: D. Formation of rainbow involves all dispersian, refraction and internal reflection.

1. meeting of cumulonimbus clouds in the sky
2. lightning that separates the nimbus clouds
3. violent upward movement of air and water particles

Select the correct answer using the codes given below.

Explanation: D. Thunderstorms result from the rapid upward movement of warm, moist air. They can occur inside warm, moist air masses and at fronts. As the warm, moist air moves upward, it cools, condenses, and forms cumulonimbus clouds that can reach heights of over 20 km (12.45 miles). The thunderstorms are associated with the cumulonimbus clouds. These clouds normally form on warm sunny days but they can also be found on cold front. But this question is asking about the Thunder i.e. the sound produced. The lightning generates between 100 million and 1 billion volts of electricity and can heat the air to around 50K

Explanation: A. Gravity is the feeble force among the four.

1. If pure hydrogen is used as a fuel, the fuel cell emits heat and water as by-products.
2. Fuel cells can be used for powering buildings and not for small devices like laptop computers.
3. Fuel cells produce electricity in the form of Alternating Current (AC).

Which of the statements given above is / are correct?

Explanation: A. When pure hydrogen is used as the fuel, the only by-products generated from the fuel cell are pure water and heat. Similar to a battery, a fuel cell with a supply of hydrogen and oxygen can be used to power devices that use electricity.