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Atmospheric pressure refers to the force exerted by the weight of air molecules on a surface. At sea level, where the density of air is greatest, this pressure is standardized for scientific measurements and everyday applications. The accepted value is 760 millimeters of mercury (760 mmHg), which is equivalent to 1 atmosphere (1 atm) or 101.3 kilopascals (kPa).
This standard value originates from the famous experiment by Evangelista Torricelli (1643), who invented the mercury barometer. He demonstrated that atmospheric pressure could support a mercury column approximately 760 mm high at sea level. Since then, this measurement has been adopted globally as a standard reference.
Scientific Measurements: It provides a baseline for pressure measurement in physics, chemistry, and meteorology.
Aviation and Space Science: Aircraft performance and oxygen availability are often compared to this baseline value.
Human Physiology: At higher altitudes, atmospheric pressure drops below 760 mmHg, reducing oxygen availability and leading to altitude sickness.
Industrial Applications: Calibration of pressure instruments and weather forecasting relies on this standard.
746 mm (Option A): Too low; below the recognized standard.
820 mm (Option C): Too high; corresponds to pressure below sea level or unusual atmospheric conditions.
None of these (Option D): Incorrect because 760 mm is the correct and internationally accepted value.
In conclusion, the standard atmospheric pressure at sea level is 760 mmHg, a crucial constant in physics, meteorology, and engineering
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