A lab operation results in releasing air containing chloroform into the environment. To treat this, an absorber is being proposed to scrub the gas using pure water to decrease the chloroform concentration to 10ppm. If the air stream enters the column at 1000kmol/h with 200ppm chloroform and the water enters at 187,500kmol/hr. How many stages should be designed using: a) Graphical method. b) Kremser method