Answer is: 1) formula mass.
Formula weight is given in atomic mass units (amu).
The unified atomic mass unit (amu) is a standard unit of atom mass.
Atomic mass of carbon atom is 12.01 amu.
Atomic mass of hydrogen atom is 1.01 amu.
Atomic mass of bromine atom is 79.9 amu.
In chemical compound C₃H₆Br₂ there are three carbon atoms, six hydrogen atoms and two bromine atoms.
M(C₃H₆Br₂) = 3 · 12.01 amu + 6 · 1.01 amu + 2 · 79.9 amu.
M(C₃H₆Br₂) = 201.89 amu; formula mass of one molecule.
