Answer ; The question is missing in some details, but here are he details ;
The two naturally occurring isotopes of bromine are
81Br (80.916 amu, 49.31%) and
79Br (78.918 amu, 50.69%).
The two naturally occurring isotopes of chlorine are
37Cl (36.966 amu, 24.23%) and
35Cl (34.969 amu, 75.77%).
Bromine and chlorine combine to form bromine monochloride, BrCl.
Explanation:
The detaile calculation is as shown in the attachment.
