71) The value of the product of molecular weight and the gas characteristic constant for all the gases in M.K.S. unit is

72) On volume basis, air contains following parts of oxygen

73) Universal gas constant is defined as equal to product of the molecular weight of the gas and

74) The value of the product of molecular weight and the gas characteristic constant for all the gases in S.I. units is

75) For which of the following substances, the internal energy and enthalpy are the functions of temperature only