Answer:
The correct answer is:48.5% X-59, 51.5% X-61
Explanation:
Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.
Formula used to calculate average atomic mass follows:
.....(1)
Let the fractional abundance of X-59 isotope be 'x'. So, fractional abundance of X-61 isotope will be '1 - x'
For X-59 isotope:
Mass of X-59 isotope =59 g/mol
Fractional abundance of X-59 isotope = x
For X-61 isotope:
Mass of X-61 isotope = 61 g/mol
Fractional abundance of X-61 isotope = 1 - x
Average atomic mass of chlorine = 35.4527 amu
Putting values in equation 1, we get:
![59.97 g/mol=[(59 g/mol\times x)+(61 g/mol\times (1-x))]\\\\x=0.515](https://tex.z-dn.net/?f=59.97%20g%2Fmol%3D%5B%2859%20g%2Fmol%5Ctimes%20x%29%2B%2861%20g%2Fmol%5Ctimes%20%281-x%29%29%5D%5C%5C%5C%5Cx%3D0.515)
Percentage abundance of X-59 isotope = 
Percentage abundance of X-61 isotope = 
Hence, the percentage abundance of both the isotopes X-59and X-61 are 51.5% and 48.5% respectively.
