Question

Which of the following represent the correct values of normal atmospheric pressure?

• A. $76mm$ of mercury and $101.3$ pascals
• B. $101.3\text{kilopascals and}76cm$ of mercury
• C. $101.3\text{kilopascals and}76mm$ of mercury
• D. $76mm$ of mercury and $76cm$ of mercury

Answer 1

The correct option is B $101.3\text{kilopascals and}76cm$ of mercury

Atmospheric pressure is the pressure exerted by the atmosphere, or rather the weight of air above a point on Earth per unit area. It can be measured using a barometer. The unit of pressure is pascals. As we move to a higher altitude, the weight of air decreases and the pressure lessens. So, atmospheric pressure decreases with an increase in elevation. At sea level, a barometer shows the value of standard or normal atmospheric pressure, which is equivalent to the pressure exerted by a $760mm\text{or}76cm$ tall column of mercury or $101.3\text{kilopascals}$.