Paper 2 · Diffusion of ammonia and hydrogen chloride; methods of purification
Which of the following correctly defines the term diffusion?
AThe movement of particles from a region of higher concentration to a region of lower concentration.
BThe net movement of water molecules from a region of high water potential to a region of low water potential across a partially permeable membrane.
CThe escape of a gas through a small hole into a vacuum.
DThe process by which a solid changes directly into a gas without passing through the liquid state.
Explanation: Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. Option B describes osmosis, option C describes effusion, and option D describes sublimation.
Derived from ZIMSEC Chemistry 5071/2 Paper 2 Theory, November 2017, Q1
