Respuesta :
Answer is 63.04amu.
Explanation: We are given in the question that an element has two main isotopes 1 and 2.
Mass Number of isotope 1 = 62 amu
Mass Number of 2 isotope = 65 amu
% abundance of isotope 1 = 66%
Fractional abundance of isotope 1 = 0.66
Total fractional abundance = 1
Fractional abundance of isotope 2 = (1-0.66)
                             = 0.34
For calculating he atomic mass of element, we use
[tex]\text{atomic mass of element}=\left [(\text{fractional abundance of isotope 1})\times (\text {atomic mass of isotope 1)} \right ]+\left [(\text{fractional abundance of isotope 2})\times (\text {atomic mass of isotope 2}) \right ]+...[/tex]
We have only 2 isotopes for an element, so the formula stops at isotope 2 only.
By putting the values in the above equation, we get
[tex]\text{atomic mass of element}=(62amu\times 0.66)+(65amu}\times 0.34)[/tex]
Atomic mass of element = 63.04amu
