a. The following information refers to the isotopes of copper and was collected by using a mass spectrometer - VCE - SSCE Chemistry - Question 3 - 2006 - Paper 1

Let the percentage abundance of the 63Cu isotope be denoted as x. The percentage abundance of the 65Cu isotope will then be (100 - x).

Using the formula for calculating the relative atomic mass:

ext{Relative atomic mass} = rac{(x imes 62.93) + ((100 - x) imes 64.93)}{100}

Substituting the known relative atomic mass of copper (63.54):

63.54 = rac{(x imes 62.93) + ((100 - x) imes 64.93)}{100}

Multiplying both sides by 100:

$6354 = (x imes 62.93) + (100 - x) imes 64.93$

Expanding the equation:

$6354 = x imes 62.93 + 6493 - x imes 64.93$

Combining like terms:

$6354 = 6493 - x imes 2$

Rearranging gives:

$x imes 2 = 6493 - 6354$

$2x = 139$

Therefore:

x = rac{139}{2} = 69.5

Hence, the percentage abundance of the 63Cu isotope is approximately 69.5%.