Boron has two stable isotopes, `.^(10)B(19%)` and `.^(11)B(81%)`. The atomic mass that should appear for boron in the periodic table is

Options

A. 10.8
B. 10.2
C. 11.2
D. 10

Answer

A

Explanation

`"Average atomic mass"=(R.A.(1) xx M.No +R.A.(2) xx M.No.)/(R.A.(1)+R.A.(2))`
Where, R.A. = Relative abundance
M.No = Mass number
`=(19 xx 10+81 xx 11)/(100)=10.81`