Iron(II) sulfate forms several hydrates with the general formula FeSO₄, H₂0, where x is an integer. If the hydrate is heated, the water can be driven off, leaving pure FeSO₄, behind Suppose a sample of a certain hydrate is heated until all the water is removed, and it's found that the mass of the sample decreases by 45.%. Which hydrate is it? That is, what isx?