Question

Given that the abundances of isotopes ${}^{54}Fe$ , ${}^{56}Fe$ and ${}^{57}Fe$ are 5 % , 90 % and 5%.

Respectively,the atomic mass of Fe is

• A. 55.85
• B. 55.95
• C. 55.75
• D. 56.05

Answer 1

The correct option is B

55.95

Average atomic mass of Fe

= $\frac{(54\times 4)+(56\times 90)+(57\times 5)}{100}$ = 55.95