Is equal to the pressure of all the gases in the air above us at sea level?!

O A. Atmosphere

. O B. Millimeter of mercury

. O C. Pascal

• O D. Kelvin

A. Atmosphere

Explanation:

One atmosphere is equal to the pressure of all the gases in the air above us at sea level.

Such as the gases exert a pressure in a container derived from the forces exerted by the molecules that collide with the walls of the container, all the gases that are above us exert a pressure on us and all the objects that surround us.

Since the height of gases above the ground at sea level is greater than that at upper levels, the atmospheric pressure varies: it decreases when the altitude increases.

So, the pressure of the atmosphere at sea level has been defined as one atmosphere, which is what leads to the correct answer to this question (option A).

On the other hand, milimeeter of mercury is a different unit to measure pressure, The equivalence is 1 atm = 760 mmHg.

Pascal is SI unit to measure pressure. 1 atm = 1.01325 * 10⁵ Pa.

Kelvin (option D.) is a unit of absolute temperature.