Question

Given that the abundacne of isotopes `.^(54)Fe`, `.^(56)Fe`, and `.^(57)Fe` is 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

Correct Answer - B
From the given relative abundance, the average weight of Fe can be calculated as
`A = (54 xx 5 + 56 xx 90 + 57 xx 5)/(100) = 55.95`