To calculate atomic mass, you need to know the mass of each individual isotope of an element and its abundance. Multiply the mass of each isotope by its abundance (as a decimal) and add all the results together. This will give you the atomic mass in atomic mass units (AMU).
The formula for calculating atomic mass is: (mass of isotope 1 x abundance of isotope 1) + (mass of isotope 2 x abundance of isotope 2) + ... + (mass of isotope n x abundance of isotope n).
Atomic mass is expressed in atomic mass units (AMU). One AMU is equal to 1/12 of the mass of a carbon-12 atom. It is also sometimes expressed in grams per mole (g/mol).
You can find the mass of a specific isotope by looking it up on the periodic table or by using a mass spectrometer. The mass spectrometer measures the mass-to-charge ratio of atoms and can identify the different isotopes present in a sample.
To solve for pi meson's mass in AMU, you would need to know the mass of each individual isotope of pi meson (pi+ and pi-) and their respective abundances. Then you would use the formula for calculating atomic mass, substituting in the mass and abundance values for each isotope of pi meson. The result will be the atomic mass of pi meson in AMU.