70.The hydraulic jack to lift heavy vehicles in automobile service stations is one
   of the applications of
   (a) Pascal"s law
   (b) Principle of Archimedes
   (c) Boyle"s law
   (d) Hooke"s law
Ans: (a)
71.A simple mercury barometer is found in a slightly slanting position. The
   atmospheric pressure
   (a) is found by measuring the slanting height of the mercury column
   (b) is given by the vertical height
   (c) cannot be measured with it
   (d) u) can be measured by both the methods described above
Ans: (b)
72.The instrument used to determine the RD (Relative Density) of a liquid by
   the principle of floatation is
   (a) Hygrometer
   (b) Hypsometer
   (c) Hydrometer
   (d) Densimeter
Ans: (c)
73.A lactometer is used to
   (a) find out the specific gravity of liquids
   (b) measure the volumes of liquids
   (c) test the purity of milk
   (d) determine the strength of acid in car batteries
Ans: (c)
74.Solids have definite shapes. This is because
   (a) the forces of cohesion of the molecules within are very much less in them
   (b) the forces of cohesion are very large
   (c) the forces of adhesion are large
   (d) the forces of adhesion are less
Ans: (b)