Question

Boron has two stable isotopes, ¹⁰B (19%) and ¹¹B (81%). The atomic mass that should appear for boron in the periodic table is _______.
(A) 10.0
(B) 10.2
(C) 10.8
(D) 11.2

Answer 1

11+ 10= 21/2 =10.5 but B11(81%)
So , it should be greater than 10.5 but less than 11 . Hence , answer is 10.8