The atomic mass of lead : 207 g/mol
The mass of this basic particle is expressed in atomic mass units
This atomic unit uses the standard atomic mass, that is, the C-12 isotope
1 atom C-12 = 12 atomic mass units
The atomic mass of an element (amu = u = g/mol) = the mass in grams of one mole of an element.
The mass of 0.2 mol of Lead equals 41.4 grams, so the atomic mass :
[tex]\tt \dfrac{41.4}{0.2}=207~g/mol[/tex]