71.
The National Chemical Laboratory is situated in

72.
Equal masses of oxygen, hydrogen and methane are kept under identical conditions. The ratio of the volumes of gases will be

73.
The mass number of an atom is equal to

74.
The maximum number of covalent formed by nitrogen is

75.
The formula C6H5-CO-CH3 represents

76.
The metal that is usually extracted from sea water is

77.
The method of concentrating the ore which makes use of the difference in density between ore and impurities is called

78.
The inert gases are ____ in water.

80.
The names of the scientists, Newlands, Mendeleev, and Meyer are associated with the development of