Question

boron has two isotopes B-10,B-11. The average atomic mass of boron is found to be 10.80u. Calculate the percentage abundance of `B^(10)`isotope :-
A. 80
B. 20
C. 25
D. 75

Answer 1

Correct Answer - B
Hence to maintain the weight of 1 mole, value of A vogadro constant gets doubled
Let abondance of B-10 be xx and B-11 be 100-x Avg. mass=
`(M_(1)X_(1)+M_(2)X_(2))/(X_(1)+X_(2))rArr((10xxX)+[11xx(100-X)])/(100)=10.80`
rArr X = 20