According to the definitions of mass and mole fractions, which of the following statements are true?
?The sum of mole fractions for a real-gas mixture does not equal to 1 .
?Mass and molar number are related through the molecular mass.
?Mass fractions of a mixture cannot be converted from the mole fractions.
?The sum of mass fractions for an ideal-gas mixture equals to 1 .
?Generally, the mass and mole fractions of a mixture are not the same.