2.5mol
首先要明确一点,1mol氯气中只有一个氯原子能参与取代反应,故0.25mol一氯甲烷需0.25mol氯气,0.25mol二氯甲烷需0.5mol氯气,0.25mol三氯甲烷需0.75mol氯气,0.25mol四氯化碳需1mol氯气,共计2.5mol