Given: m (mass of the taken piece of iron) = 5.7 kg.
Constants: according to the condition M (molar mass of iron) = 57 * 10-3 kg / mol.
The amount of substance contained in a taken piece of iron is determined by the formula: ν = m / M.
Let’s calculate: ν = 5.7 / (57 * 10-3 kg) = 100 mol.
Answer: The taken piece of iron contains 100 moles of the substance.
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