\textbf{205-} If one ton of gypsum (calcium sulfate dihydrate) with a purity of \textbf{85\%} is heated to produce solid anhydrous product, how many kilograms of water are obtained? (Grams on kcal have no effect.)
$$(Ca = 40,\ S = 32,\ O = 16,\ H = 1 : \text{g.mol}^{-1})$$
(1) $911$ \hfill (2) $895$ \hfill (3) $872$ \hfill (4) $761$
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