To 150 g of a solution of copper sulfate (II) with a mass fraction of 8% was added another 8 g of the same salt. Mass fraction of salt in the resulting solution is equal to
150 g of an 8% solution contains 150 * 0.08 = 12 g of salt
Therefore, its mass fraction in the final solution will be equal to:
(12 + 8) * 100 / (150 + 8) = 12.66%
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