21) Which one of the following sets of colour combinations is added in colour vision in TV?
(A) Red, green and blue
(B) Orange, black and violet
(C) White, red and yellow
(D) Yellow green and blue
22) A train goes past a railway station at a high speed. A young boy standing on the edge of the platform is likely to
(A) Remain unaffected
(B) Fall away from the train
(C) Fall towards the train
(D) Fall away from or towards the train depending on the speed
23) Water s a highly effective coolant for car engine because
(A) Water is good conductor of heat
(B) Water has very high specific heat capacity
(C) Water boils at a comparatively high temperature
(D) Evaporation of water produces lot of cooling
24) Scalding with steam is more severe than scalding by boiling water because
(A) Steam can penetrate the skin
(B) Steam is at a higher temperature
(C) Steam contains more energy than boiling water
(D) Steam is at a higher pressure
25) In order to prevent the corrosion of iron pipes they are often coated with a layer of zinc. This process is termed as
(A) Electroplating
(B) Annealing
(C) Galvanisation
(D) Vulcanisation
26) The cracking sound heard when dry hair is combed with a hard rubber comb is due to
(A) The hair barging against the charged comb
(B) Small electric sparks
(C) The rubbing of the comb with the hair
(D) None of the above
27) Detergents dissolved in water help in cleaning clothes by
(A) Increasing the temperature of water
(B) Reacting chemically with dirt
(C) Reducing the surface tension of water
(D) Dissolving Dirt
28) The absorption of Ink by blotting paper involves?
(A) Viscosity of Ink
(B) Capillary action phenomenon
(C) Diffusion of ink through blotting
(D) Siphon action
29) Materials for rain-proof coats and tents owe their water proof properties to
(A) Surface Tension
(B) Viscosity
(C) Specific gravity
(D) Elasticity
30) A satellite moving round the earth with uniform speed has
(A) An accelerated motion
(B) No acceleration at all
(C) Uniform acceleration
(D) Uneven acceleration