$**5\mathrm{.}2\mathrm{.}9$ The overall yield of a product on a substrate in lute value of the production rate divided by the rate of consumption of the feed in the substrate $($the liquid containing the cells, nutrients, etc.$).$ The overall chemical reaction for the oxidation of ethylene $(C_2{H}_4)$ to epoxide $(C_2{H}_{4}O)$ is

$2C_2{H}_4+O_{2}2C_2{H}_{4}O$

Calculate the theoretical yield $(100\%$ conversion $C_2{H}_4)$ of $C_2{H}_{4}O$ in moles per mole for Reaction $($a$).$