Question

Compare relative molar mass and relative formula unit mass

Answer 1

Relative molecular mass is same as relative formula mass.

Relative formula mass is the sum of the atomic mass of the atoms in the given compound.

 For example relative formula mass of CO is 1 2+ 16 = 28 

Relative molecular mass is the sum of all the relative atomic masses of the atoms in a molecule and is actually equal to molecular mass. 

Therefore , HNO3 = 63

 H2SO4 = 98

 HCl  = 36.5  

Answer 2

both are same 

Relative atomic mass is the summation of the individual masses of the atoms. This mostly applied to molecular compounds like water, ammonia, etc. That is, atomic mass of molecules.

Formular mass applies to ionic compounds. Because they are composed of aggregates of ions arranged in a crystal lattice. It's wrong to say “molecules of Sodium Chloride”.