Explanation: There are 2 given isotopes of Copper.
Mass number of Isotope 1 : 63amu
Mass number of Isotope 2: 65 amu
Let the fractional abundance of isotope 1 be 'x', so the fractional abundance for Isotope 2 will be '1-x'
The average atomic number of Copper given is 63.55 amu.
So, the formula for average atomic mass is given by:
[tex]\text{Average atomic mass of an element}=_{i=1}^n\sum{\text{atomic mass of isotopes}_i\times {\text {fractional abundance}_i}[/tex]
Putting values in above equation, we get:
[tex]63.55=[(63\times x)+(65\times (1-x))]\\\\x=0.725[/tex]
The fractional abundance of Isotope 1 = 0.725
The fractional abundance of Isotope 2 = 0.275
So, the natural percentage abundance for isotope 1 = 72.5%
The natural percentage abundance for isotope 2 = 27.5%
Whenever more number of isotopes are present of an element are present, we take the average atomic mass of that element.
