\textbf{226.} From the reaction: $\mathrm{C_2H_4(g) + H_2O(g) \rightleftharpoons C_2H_5OH(g)}$, $K=2$, used in industry for the preparation of ethanol. If two moles of ethylene and two moles of water, at a certain temperature, in a two-liter closed container reach equilibrium, the percent yield of this process is which of the following?
(1) $60$ \quad (2) $\Delta 0$ \quad (3) $81$ \quad (4) $85$
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