Question

can we write relative molecular mass in grams​

Answer 1

Since the standard unit for expressing the mass of molecules or atoms (atomic mass unit or the dalton) is defined as 1/12 of the mass of a 12C atom, it follows that the molar mass of a substance, measured in grams per mole, is exactly equal to its mean molecular or atomic mass, measured in unified atomic mass units .

Answer 2

it is exactly equal to its mean molecular or atomic mass, measured in unified atomic mass units .