Into a $250$ ml round bottomed flask equipped with a stirrer and gas inlet and outlet tube. $10$ ml of pure acrylonitrile and $6$ ml of reducing agent are dissolved in $100$ ml distilled water. Nitrogen is bubbled through this solution for about $(1)/(2)$ h$.5,7$ ml ceric ammonium nitrate stock solution $(2$M$)$ is added dropwise to the reaction mixture in about $20$ min by dropping funnel. The mixture is stirred at $30\backslash$deg C for about $1$ h$.$ The precipitated polymer is filtered, washed with water then with methanol and hot methanol and dried at $50\backslash$deg C in vacuum. The amount of polymer formed is $6\mathrm{.}5$ grams. Calculate the efficiency.