Which process is characterized by the movement of particles from an area of a high concentration to an area of low concentration across the plasma membrane without the use of energy

Osmosis

Explanation:

Passive transport does not require energy for movement in and out of a place or across a membrane e.g a cell.

Osmosis uses passive transport to move materials in and out of a cell by setting up concentration gradient through a distance.

Osmosis can be defined as the movement of molecules or particles of a solution from an area of higher concentration to that of lower concentration through a semi-permeable membrane e.g plasma membrane. As we can see, the difference in concentration is the drive for the transport between the two medium. When the concentration is the same, there won't be any movement again.