At partial pressure of zero how much oxy-gen is attached to hemoglobin molecule? A100%B50%C33.33%D0%Answer: A. 100% Read Explanation: Oxygen saturation is a measure of the amount of hemoglobin that is bound to molecular oxygen at a given time point. A hemoglobin molecule becomes 100% saturated with oxygen (1.34 L of oxygen) at a PO2 of 100 mmHg. Read more in App