When a steel ball is placed on the surface of mercury, it does not sink because
of the surface tension of mercury
mercury is a semi-solid
of the high viscosity of mercury
the density of mercury is greater than that of steel
Correct Answer :
D. the density of mercury is greater than that of steel
Related Questions
Where does the centre of gravity of a rubber ring lie?
on the outer surface
in the inner surface
at the centre of the ring
None of the above
Mercury does not stick to glass because
cohesive forces between the mercury molecules are greater than adhesive forces between mercury and glass molecules
the adhesive forces between mercury and glass molecules are greater than the cohesive forces
both the cohesive and adhesive forces are equal
None of the above
A piece of ice is Boating In water kept in a beaker. When all the ice melts the level of water will
first rise and then fall
fall
remain the same
rise
Choose the correct answer
Microphone converts sound energy into electrical energy.
Electric fan converts electrical energy into mechanical energy.
Battery converts chemical energy into electrical energy.
All the above
The velocity of sound in air increases with
the rise of temperature
rise of its frequency
decrease in humidity
fall of temperature
When one enters a dark room after being in bright light one is not able to see anything clearly for a while because
the retina of the eye moves forward
the retina of the eye moves backward
c).the iris is unable to dilate the pupil immediately to be able to see things
the eye has no power of accommodation
Sun spots are
the mountains found on the surface of the Sun
the dark patches on the sun having less temperature than the normal sun's surface
ionized gas found near the solar surface
the magnetic storms on the surface of the Sun
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
We see the flash of lightning before hearing the thunder because
light travels very much faster than sound
sound travels faster than light
lightning occurs nearer than thunder
both travel at the same speed
The colour of the light which travels through glass with minimum speed is
red
violet
green
yellow
Mica is used in an electric iron because it is a
good conductor of heat
good conductor of electricity
bad conductor of electricity
Both (a) and (b) above
Which of the following is known as freon?
Liquid ammonia
Carbon tetrafluoride
Dichloro-difluoro-methane
Sulphur dioxide
Chronometer is an instrument to measure
heat
electric potential
time
distance between two points
Sound waves in air are
transverse
longitudinal
transverse and longitudinal
neither transverse nor longitudinal
Sound waves In 'air travel faster if
frequency is higher
wavelength is smaller
pitch is smaller
air is warmer
Hydrophone is an instrument used
for measuring relative density of liquids
by ships to pass on messages
for determining the depth of ocean bottoms etc.
by deaf people to aid hearing
When the resistance of a circuit increases the current will
increase
decrease
remain the same
None of the above
Of the following types of electromagnetic radiation which has the longest wavelength?
ultraviolet rays
gamma rays
radio waves
infrared waves
The image formed by a plane mirror is
of the same size as the object
at the same distance behind the mirror as the object is in front of it
virtual and laterally inverted
All the above
It is difficult to bon potatoes at the top or a mountain because
the water available is hard
it is colder than at sea level
the potatoes become hard
the boiling point of water is lower at that height on account of low atmospheric pressure
The electron has a mass equal to
1.9 x 10-13 kg
9.1 x 10-31 kg
1 x 10-15 kg
1.6 x 10-19 kg
When a bowler spins a ball, it changes its direction in the air. This is due to
turbulence caused by the wind
buoyancy of air
unequal pressures acting on it
sudden change in the direction of the wind
The presence of impurities
lowers the melting point of ice
raises the melting point of ice
has no effect on the melting point of ice
may lower or raise the melting point depending upon the type of impurities
A boy sitting in a train moving with a uniform velocity drops a coin outside. A man standing outside the train will find the trajectory of the coin to be
a parabola
a horizontal straight line
a vertical straight line
a circle
The ballistic missile, Agni 11, tested by India has a maximum range of
1000 km
1500 km
2000 km
500 km
The electrical domestic tube light gives white fiourescent light because of
collision between molecules of filled gas under electric current
heavy current
vacuum inside the tube
falling of ultra violet rays on the white inner coating of the tube
A balloon ruled with hydrogen will
continue going upwards uninterrupted
reach a particular height and remain floating
burst after reaching some height
reach a particular height and start coming down
Railway tracks are banked on curves so that
the necessary centrifugal force may be obtained from the horizontal component of the weight of the train
the frictional force between the track and the wheels is avoided
the necessary centripetal force may be derived from the horizontal component of the weight of the train
None of these
A boat loaded with rocks floats in the middle of a swimming pool. A man in the boat throws the rocks overboard. The level of water in the pool will
increase
decrease
remain the same
first decrease and then increase
Choose the correct answer
Microphone converts sound energy into electrical energy.
Electric fan converts electrical energy into mechanical energy.
Battery converts chemical energy into electrical energy.
All the above