11) The penetration of x-rays through an object depends upon the object's
(A) Density
(B) Shape
(C) Pressure
(D) Size
12) To find the hidden secrets under the water, the ships and submarines use the
(A) Radiation system
(B) Sonar system
(C) X-ray system
(D) Radiation system
13) Recording of brain waves from outer surface of head is called
(A) E.C.G.
(B) MRI
(C) C.T. scan
(D) E E.G
14) Ball bearings are used in cycles, scooters, etc. to
(A) Reduce the friction between the wheel and the axle
(B) Increase the friction between the wheel and the axle
(C) Reduce the friction between ground and the wheel
(D) None of these
15) Steel is more elastic than rubber because
(A) Its density is high
(B) It is a metal
(C) Ratio of stress to strain is more
(D) Ratio of stress to strain is less
16) What does make the blood look red?
(A) Red corpuscles
(B) Hemoglobin
(C) Plasma
(D) Certain secretions
17) In railway tracks, a small gap is left between the rails
(A) To allow for the expansion during heat
(B) To save the cost of metal
(C) To permit the shrinkage of metal
(D) None of the above
18) Friction can be reduced by changing over from
(A) Sliding to rolling
(B) Rolling to sliding
(C) Potential energy to kinetic energy
(D) Dynamic to static
19) Ice blocks are covered with sawdust
(A) To prevent the dust from collecting on the ice
(B) Because ice being cold cannot be lifted with bare hands
(C) To provide necessary insulation from heat
(D) None of the above
20) The acid used in a car battery is
(A) Hydrochloric acid
(B) Nitric acid
(C) Sulphuric acid
(D) Carbonic acid