Q. On a clean glass plate a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical because
A. mercury is a metal
B. density of mercury is greater than that of water
C. cohesion of mercury is greater than its adhesion with glass
D. cohesion of water is greater than its adhesion with glass
Q. Suitable impurities are added to a semiconductor depending on its use. This is done in order to
A. increase its life
B. enable it to withstand higher voltages
C. increase its electrical conductivity
D. increase its electrical resistivity
Q. Stars twinkle because
A.the intensity of light emitted by them changes with time
B. the distance of the stars from the earth changes with time
C. the refractive index of the different layers of the earth’s atmosphere changes continuously, consequently the position of the image of a start changes with time
D. the light from the star is scattered by the dust particles and air molecules in the earth’s atmosphere
Q. It takes much longer to cook food in the hills than in the plains, because
A.in the hills the atmospheric pressure is lower than that in the plains and therefore water boils at a temperature lower than 100oC causing an increase in cooking time
B. due to low atmospheric pressure on the hills, the water boils at a temperature higher than 100oC and therefore water takes longer to boil
C.in the hills the atmospheric density is low and therefore a lot of heat is lost to the atmosphere
D.in the hills the humidity is high and therefore a lot of heat is absorbed by the atmosphere leaving very little heat for cooking
Q. Moment of inertia is
A.vector
B. scalar
C. phasor
D. tensor
Q. Of the following natural phenomena, tell which one known in Sanskrit as ‘deer’s thirst’?
A.Rainbow
B.Earthshine
C.Halo
D.Mirage
Q. Inside an aeroplane, flying at a high altitude,
A.the pressure is the same as that outside
B.normal atmospheric pressure is maintained by the use of air pumps
C.the pressure inside is less than the pressure outside
D.normal humidity and partial vacuum are maintained
Q. Sound travels with a different speed in media. In what order does the velocity of sound increase in these media?
A.Water, iron and air
B.Iron, air and water
C.Air, water and iron
D.Iron, water and air
Q. One thousand microns is equal to
A.10-3m
B.10-6m
C.10-9m
D.10-12m
Q. Sound travels at the fastest speed in
A.steel
B.water
C.air
D.vacuum
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