The temperature at which the motion of particles theoretically ceases is

0K or - 273°C

Explanation:

The temperature at which the motion of particles ceases is 0K or - 273°C. At this temperature the motion of particles is theatrically at rest. This temperature was explained in Charles law

Charles' Law: Charles' Law states that the volume of a given mass of gas is directly proportional to it absolute temperature.

Charles law can be expressed mathematically as

V/T = V'/T'

Where V and V' = Are initial and Final volume respectively, T and T' = Initial and Final Temperature respectively

0 K or - 273.15°C

Explanation:

Temperature is a measure of the kinetic energy of the molecules of a body. At the absolute zero or 0 K temperature, the kinetic energy is 0 J. Kinetic energy is a measure of the velocity of the molecules, hence, theoretically, the molecules stop moving.