1. 15 ppm means 15 parts in million (10^{6} ) parts by mass in the solution

% of mass = \(\frac{15}{10^6}\) x 100 = 1.5 x 10^{-4}

2. Taking 15g chloroform in 10^{6 }g of the solution

Mass of the solvent = 10^{6} g

Molar mass of CHCl_{3} = 12 + 1 + (3 x 35.5) = 119.5 g mol^{-1}

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