Define pressure. Give its units.

Explanation

It is defined as the force exertd by a gas on unit area of the wall
Pressure `=("Force")/("Area")`
The SI unit of pressure is the Pasaal `(Pa)_(2)` named after the French Mathematician and Physicist Blaise Pascal, and
`I= Pa=1Nm^(-2)`
`1N=1 Kg m s^(-2)`