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 (u) Relative Size 157.836 0.2569 159.834 0.4999 161.832 0.2431 (e) Calculate the abundances of the two isotopes. Calculate the abundance of the heavier isotope.