BrCl has three molecular mass depending upon the different isotopes which participates in its formation; given that chlorine has only two isotopes 35 and 37; we are said to predict Bromine's possible isotopes, which are-
114-35 = 79
116-35 = 81
118-35 = 83
114-37 = 77
116-37 = 79
118 -37 = 81
Why are 83 and 77 neglected from being possible isotopes?