The mass number and the atomic number of an element are X and Y respectively. The number oC neutrons in the atom of that element is
X
Y
X + Y
X Y
Correct Answer :
D. X Y
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Air escaping rapidly from a narrow orifice in an inflated tyre feels cool because
the speed with which it escapes cools it down
of the higher temperature of the surroundings
of sudden expansion causing loss of internal energy
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In very cold countries alcohol is used as a thermometric liquid because
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alcohol can be coloured for its level to be seen easily
its freezing point is very low
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A spherical mirror is
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a reflecting spherical surface
a parabolic reflecting surface
a flat reflecting surface
The body of an electrical appliance is earthed in order that
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a short circuit may be prevented
current may pass to the earth in case of a short circuit without doing any harm to the person
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30°
45°
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When light passes from air to glass, its velocity in glass
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decreases
remains unchanged
first decreases then increases
If an object is placed between two parallel plane mirrors, the number of images formed will be
1
infinite
0
4
The numerical reading of the Fahrenheit thermometer of a given temperature
is proportional to that of the Celsius thermometer
is always greater than that of the Celsius thermometer
is always less than that of the Celsius thermometer
may be greater than or less than or equal to that of the Celsius thermometer
If you want a sound proof room, the walls should be
able to refract the sound
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All the above
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equal to half its focal length
equal to its focal length
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The audible range of a normal human ear is frequencies ranging from
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50 to 15000 Hz
20 to 20000 Hz
15 to 50000 Hz
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intensity of light
density of a liquid
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All the above
Mercury is used in thermometers because
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it has uniform expansivity
it has high boiling point and low freezing point
of all the above
The hydraulic jack to lift heavy vehicles in automobile service stations is one of the applications of
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Principle of Archimedes
Boyle's law
Hooke's law
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9.1 x 10-31 kg
1 x 10-15 kg
1.6 x 10-19 kg
A man stands in a lift which accelerates upwards. The resultant reaction force on the floor of the lift is
greater than the weight of the man
less than the weight of the man
same as the weight of the man
zero
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nuclear fission
nuclear fusion
chemical combustion
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When the velocity of a body is halved
its momentum is halved
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its acceleration is halved
its potential energy is halved
A photon is
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light source used in photography
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sun-light
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rise of its frequency
decrease in humidity
fall of temperature
The velocity of sound in air increases with
the rise of temperature
rise of its frequency
decrease in humidity
fall of temperature
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breakup of the nucleus of a heavy atom into two nearly equal halves emitting two or three neutrons and releasing large amounts of nuclear energy in the process
the scattering of neutrons
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A lightning conductor installed in a building
does not allow the lightning to fall on the building at all
drives away the charged clouds
forces the lightning to fall on other buildings near that building
conducts the electric charges to the ground when lightning strikes the building
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in the earth wire
anywhere
Powder clings to the skin because of
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adhesion
capillary action
absorption
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the opposite direction of the motion
all the directions
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