(a) TW Richards
    (b) FW Aston
    (c) Stas
    (d) Urey
Ans: (d)
71. White vitriol is
    (a) ZnSO4 . 7H2O
    (b) FeSO4 . 7H2O
    (c) MgSO4 . 7H2O
    (d) CaSO4 . 2H2O
Ans: (a)
72. The human body contains about
    (a) 50% water
    (b) 10% water
    (c) 70% water
    (d) 20% water
Ans: (c)
73. Rain water collected after a shower la very pure because
    (a) the initial showers wash the atmosphere free from most of the impurities
    (b) it contains desirable salts like sodium chloride and ammonium nitrate
    (c) it dissolves the gases in the atmosphere like ozone which are good for health in small quantities
    (d) it is supposed to be "heaven sent"
Ans: (a)
74. The best specimen for drinking purposes is
    (a) rain water
    (b) river water
    (c) conductivity water
    (d) deep well water
Ans: (d)
75. Which of the following is not a characteristic of potable water?
    (a) It must be free from suspended impurities
    (b) It must be free from harmful bacteria
    (c) It must contain traces of sodium bicarbonate
    (d) It must have a fishy odour
Ans: (d)
76. "Boiler scales" contain
    (a) calcium carbonate
    (b) magnesium bicarbonate
    (c) calcium sulphate
    (d) magnesium sulphate
Ans: (a)
77. One of the ingredients of the paste on the side of a match box is
    (a) phosphorus pentaoxide
    (b) phosphorus trichloride
    (c) phosphorus trisulphide
    (d) phosphorus trioxide
Ans: (c)
78. Which of the following is not a supporter of combustion?
    (a) Oxygen
    (b) Air
    (c) Hydrogen