If the relative atomic mass of CH2O is calculated it's empirical formula (C=12,H=1,O=16)
Your post makes no sense as written.
To calculate the relative atomic mass of a compound, you need to know the atomic masses of its constituent elements and their respective ratios.
In the case of CH2O, the empirical formula indicates that there is one carbon (C), two hydrogen (H), and one oxygen (O) atom in the compound. Given the atomic masses of C = 12, H = 1, and O = 16, you can calculate the relative atomic mass by adding up the atomic masses of all the atoms involved.
Relative atomic mass of CH2O = (12 + 2*1 + 16) = 12 + 2 + 16 = 30
Therefore, the relative atomic mass of CH2O is 30.