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Ferrous sulphate heptahydrate (FeSO4.7H2O) is used to fortify food with iron. How many grams of this salt are needed to provide 10 ppm of iron in 100 kg of wheat? (Fe = 55.85, S = 32.0, O = 16.00, H = 1.0)

1. 4.97 g
2. 2.78 g
3. 5.56 g
4. 1.00 g

Correct answer: 4.97 g

Solution

1 g of Fe corresponds to (277.85/55.85) g of the heptahydrate salt, which is about 4.97 g.

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