A pair of stars that revolve round each other is
a neutron star
a binary star
a dwarf star
a polar star
Correct Answer :
B. a binary star
Related Questions
The mixing up of two gases as a result of random motion of molecules is called
diffusion
effusion
vaporisation
sublimation
The electroplating of a metallic article
protects the article from atmospheric corrosion
gives it a more attractive appearance
Both (a) and (b) above
None of the above
Atoms which have the same atomic number but different mass numbers are called
isobars
isomers
isotones
isotopes
Alpha particles are
electromagnetic radiations
helium nuclei
negatively charged particles
neutral particles
Which of the following has the highest refractive index?
Crown glass
Water
Flint glass
Diamond
A rheostat is used
to increase the current flow in a circuit
to decrease the current flow
to measure the flow of electric current
Either (a) or (b) above
Mercury is used in thermometers because
it has high thermal conductivity
it has uniform expansivity
it has high boiling point and low freezing point
of all the above
Echoes are produced by
the reflection of sound waves
the refraction of sound waves
the interference of sound waves
reverberation of sound waves
If an empty cylinder Is half ruled with a liquid, Its centre of gravity is
shifted upwards
shifted downwards
shifted neither upward nor downward
shifted upward or downward depending on the density of the liquid
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
The planet that has got a well-developed set of rings is
Venus
Saturn
Mercury
Earth
Thick brick walls are used in the construction or a cold storage because bricks
are good conductors of heat
are cheaper
are easily obtained
are bad conductors of heat
A rod of brass la held in hand and rubbed with fur. The rod is found to have
no charge
positive charge
negative charge
can't be said
Electron-volt is a unit of
power
velocity
energy widely used in nuclear physics
number of electrons
The Milky Way is
the path of a star which is nearest to the earth
a galaxy which includes the sun
a star that is nearest to the earth
None of these
Every action has an equal and opposite reaction is Newton's law of Motion
first
second
third
fourth
The earth's nearest neighbour in space is
the Sun
the Moon
the Venus
the Mars
The maximum range of most TV signals is from 121 to 240 km only because
the curvature of earth limits the range of reception
the signals are weak
the signals are absorbed by air
the antennae are not powerful enough
In a vacuum the following three articles are dropped at the same time and from the lame height. Which will reach the ground quicker?
a stone
a piece of wood
a feather
all will reach the ground at the same time
The orbit of Venus lies between those of
Mercury and Earth
Earth and Mars
Mars and Saturn
Mars and Jupiter
Frictional force acts in
the same direction as the motion
the opposite direction of the motion
all the directions
upward direction
A series of east moving still pictures can be made to appear as a moving picture because the eye
can focus very rapidly as pictures change
is quicker than the brain
can see two images separated only if the interval' between seeing them is more than' one-tenth of a second
can shut out some of the light
Credit for starting Space Science Research in India goes to
HJ Bhabha
SS Bhatnagar
V Sarabhai
CV Raman
Under similar conditions of temperature and pressure, the velocity of sound is maximum in
helium
argon
hydrogen
oxygen
Solar radiation is preferred to other sources of energy because
it is practically inexhaustible
it is the cheapest form of energy
it does not cause pollution
All of the above
A spherical mirror is
a reflecting elliptical portion
a reflecting spherical surface
a parabolic reflecting surface
a flat reflecting surface
Meteors
look like falling stars
are really pieces of rock or metal
burn up as they shoot through the air
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
The colour of the light which travels through glass with minimum speed is
red
violet
green
yellow
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