MCQ PracticeMaximum allowable concentration of CO 2 in air for safe working is __________ ppm (parts per million).Subject: Chemical EngineeringTopic: Environmental Engineering In CeA50B1000C2000D5000Correct Answer: DPractice QuizBack to MCQsRelated MCQsCurrent flows in a circuit whenEighttenths coulomb passes a point in 4 s. The current in amperes isThe unit of electrical charge is the