Question

Bromine atom is available In two isotopes, ${}_{35}^{79}Br$ (49.7 %) and ${}_{35}^{81}Br$ (50.3 %) the average atomic mass of bromine atom is :

• A. 79.016
• B. 80.076
• C. 80.006
• D. 81.016

Answer 1

The correct option is C 80.006

As we know,
Avg. Mol. wt. $=\frac{a_1{x}_1+a_2{x}_2}{(x_1+x_2)}$
Average atomic weight $=79\times \frac{49.7}{100}+81\times \frac{50.3}{100}=80.006$