\textbf{215-} How many grams of aluminum must react with hydrochloric acid so that the gas produced, combined with 16 grams of oxygen, completes the reaction? $(Al = 27,\ O = 16\ \text{g.mol}^{-1})$
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(1) $7/7$ \hfill (2) $13/5$ \hfill (3) $9$ \hfill (4) $18$
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