| (1) 4 | (2) 5 | (3) 8 | (4) 10 |
\textbf{227 –} For the reaction $\text{A}(\text{g}) + 2\text{B}(\text{g}) \rightarrow \text{AB}_2(\text{g})$, the concentration of substance A decreases by half every hour. If the initial concentration of substance A is $1\ \text{mol·L}^{-1}$, how many hours are needed for $93.75\%$ of the $\text{AB}_2$ molecules to decompose?
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(1) 4 & (2) 5 & (3) 8 & (4) 10
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