Mass<span> is the amount of matter in an object and </span>weight<span> is the measurement of the gravitational pull on an object. The </span>mass <span>of an object is the same no matter where it is, but the </span>weight <span>of an object changes with the location of that object.</span>
Since Br-80 does not exist, maybe that means Br-79 or Br-81 have very unequal abundances. For example, Br-79 may have 75% abundance whereas Br-81 may have 25% abundance.
