Question

The average atomic mass of the copper is 63.5u.it exists as twoisotopes which are29 63Cu and29 65Cu . calculate the percentage each present in it.

Answer 1

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Answer 2

Given,

The average mass of the copper = 63.5u

To Find,

the percentage of copper in each isotope.

solution,

Let the percentage of Cu- 63 isotope = x

percentage of Cu- 65 isotope = 100-x

Average atomic mass,

63.5 = $\frac{63 X x + (65 X (100-x))}{100}$

65x- 63x = 6500- 6350

             x = 75

∴Hence

percentage of Cu- 63 isotope = 75%

percentage of Cu- 65 isotope = 100-x = 100- 75 = 25%