Answers

2016-03-28T23:51:48+05:30
average atomic mass = 49.7/100*79 + 50.3/100*81 
therefore
average atomic mass of bromine, 
= 79*49.7/100 + 81*50.3/100
= 39.263 + 40.743
= 80.006 u

i hope it helps................. 

1 5 1