Respuesta :

example

H2SO4

H = 2 atoms
S = 32 atoms
O = 4 atoms

atomic mass :

H = 1 u.m.a
S =32 u.m.a
O= 16 u.m.a

H2SO4 = 1 x 2 + 32 x 1 + 16 x 4 = 98 g/mol

hope this helps!