There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br2 molecules, and the mass of a Br2 molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br2 consists of three peaks.Mass (amu) Relative Size157.836 0.2569159.834 0.4999161.832 0.2432a. What is the origin of each peak (of what isotopes does each consist)? (Enter all particles in the form AX.)b. What is the mass of each isotope? (Calculate using the given masses.)lighter isotope ______ amuheavier isotope ______ amuc. Determine the average molecular mass of a Br2 molecule._______ amud. Determine the average atomic mass of a bromine atom._______ amue. Calculate the abundances of the two isotopes.lighter isotope _______ %heavier isotope _______ %