What is equivalent to one atmosphere in millimeters of mercury?

One atmosphere of pressure is defined as being equivalent to 760 millimeters of mercury (mmHg). This relationship comes from the historical use of mercury in barometers, where atmospheric pressure is measured by the height of a column of mercury. Thus, at sea level, the standard atmospheric pressure is precisely 760 mmHg.

This value is critical in various diving calculations and understanding gas laws, especially when discussing partial pressures and the effects of pressure on gases while diving. It is essential for divers to recognize this standard to ensure proper gas mixes and safety during dives. Other values presented do not match the established standard for atmospheric pressure, which is why they do not represent the correct answer in this context.