The fe2 + (aq) solution described in part a was produced by dissolving 4.05 g of ore in acid. what was the percentage of fe by mass in this ore sample?

Percentage by mass is the amount in mass of a component in a mixture per 100 unit of mass of the total mixture. Percentage by mass is the same as %w/w. In order to determine this value, we need to know the mass of the substance in question and the total mass of the sample. In this case, we have to know the mass of Fe by doing certain calculations. Then, we divide this value by the total mass given of the ore, 4.05 g and multiply by 100%. It should be expressed as follows:

Percent by mass = mass of Fe in ore / 4.05 g ore sample x 100

However, the question is lacking some information so we cannot really specify the answer.