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100 mL of a water sample contains 0.81 g of calcium bicarbonate and 0.73 g of magnesium bicarbonate. The hardness of this water sample expressed in terms of equivalents of CaCO 3 is - (molar mass of calcium bicarbonate is 162 g mol –1 and magnesium bicarbonate is 146 g mol –1 )

1. 100 ppm
2. 1,000 ppm
3. 5,000 ppm
4. 10,000 ppm

Correct answer: 10,000 ppm

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