Hot water is poured simultaneously in four metallic tumblers painted outside with different paints. After some time the water will be found to have cooled most in the tumbler painted.
rough white
rough black
shining white
shining black
Correct Answer :
B. rough black
Related Questions
Isotones are species of atoms containing
same number of protons but different number of neutrons
same number of neutrons but different number of protons
the same total number of protons and neutrons
same number of protons and different number of electrons
The planet that has got a well-developed set of rings is
Venus
Saturn
Mercury
Earth
Credit for starting Space Science Research in India goes to
HJ Bhabha
SS Bhatnagar
V Sarabhai
CV Raman
In the case of bodies falling under gravity which of the following remains constant at a given place?
kinetic energy
potential energy
acceleration
All the above
The radius of an atom is approximately
10-10 cm
10-12 cm
10-13 cm
10-16 cm
Which of the following apparatus is used in the electrolysis of water?
Voltmeter
Voltameter
Ammeter
Potentiometer
When an electric apparatus is fitted with a three core flexible lead the insulation on the three wires is distinctively coloured. The present international convention is
brown for earth, yellow for live, light blue for neutral
green for earth, yellow for live, brown for neutral
yellow for earth, green for live, brown for neutral
brown or red for live, light blue or black for neutral and green or yellow for earth
The attraction between similar molecules is called
inertia
adhesion
cohesion
friction
The coil of an electric heater is made of
Platinum
Tungsten
Nichrome
Copper
Holography is the technique of
taking photos of various objects
recording and reproducing three dimensional images
tracing out planets and stars in the sky
transmitting light waves
The focal length or lens or the eye is under the control or the
iris
pupil
ciliary body
cornea
Fish and other aquatic creatures can live inside a deep frozen pond because
fish are cold-blooded animals
ice is a bad conductor of heat
there will always be water just beneath the ice level
they can adapt themselves to live in ice
The base of an electric iron is brightly polished mainly
to make it smooth and frictionless
to make it rust - proof
to reduce heat loss by radiation
to make it more durable
When two similar sources vibrate with slightly different frequencies, a regular rise and fall occurs in the loudness of tone. This phenomenon Is known as
doppler effect
beats
resonance
echo
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
Rays from the headlight of a motor car are rendered parallel by suitably using
a convex mirror behind it
a concave lens behind it
a concave mirror in front of it
a concave mirror behind it
Halley's comet appears in the heavens once in
40 years
50 years
76 years
80 years
Separating particles from a suspension is effected by
centrifugal force
frictional force
gravitational force
distillation
The phenomenon of radioactivity was discovered by
Rutherford
Bohr
Henri Bacquerel
Marie Curie
In a river, the currents are fastest where the river la
wide and shallow
narrow and shallow
wide and deep
narrow and deep
The velocity of sound in a medium is
directly proportional to its pressure
inversely proportional to the square root of its pressure
directly proportional to the square root of its pressure
independent of its pressure
The speed of sound in air at 0° C is approximately
4 x 10 8 m/s
1500 m/s
330 m/s
500 m/s
Heat is transmitted from one end of a metal rod to its other end by the method of
conduction
convection
radiation
sublimation
When a bottle of perfume la opened in one corner of a room the smell spreads soon throughout the room. This is an example of
surface tension
capillarity
viscosity
diffusion
We see the sun before it actually rises on the horizon. This is due to
refraction
reflection
total internal reflection
parallax
Rays similar to X-rays but of smaller wave length that are given off by radioactive substances are
�± -rays
�² -rays
�³ -rays
Cosmic rays
A person cups his hand around the mouth when shouting. Why?
Sound energy from his mouth is then directed in one direction
The cupped hand acts as a cardboard tube of short length
The pitch of sound increases
Both (a) and (b)
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 power of a lens is
equal to its focal length
equal to its radius of curvature
equal to the reciprocal of its focal length (in metres)
equal to twice its focal length
The largest reserve of radioactive element which can be used in a nuclear reactor has been found in India, The name of the element is
Thorium
Uranium
Plutonium
Radium