National League for Nursing (NLN PAX) Practice Exam

The process illustrated by the spreading out of ammonia vapor in a closed room is diffusion. Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration, leading to an even distribution of the particles throughout the space. In this scenario, ammonia molecules, which are initially concentrated in one area, spread out to fill the entire room until they are evenly distributed.

This phenomenon occurs due to the random motion of particles. As the ammonia vapor molecules collide with air molecules and each other, they move in various directions, gradually moving from the area where their concentration is high to areas where their concentration is low. Over time, this results in a uniform distribution of the ammonia vapor throughout the room.

Convection refers to the transfer of heat through fluids (liquids and gases) by the actual movement of the fluid itself, which does not apply to the scenario of ammonia vapor simply spreading out. Evaporation involves the transition of molecules from the liquid phase to the gas phase and is not the process at play when discussing the spreading of an already gaseous substance. Conduction is the transfer of heat through direct contact between materials, which is also not relevant in the context of gas dispersion. Hence, diffusion is the process that accurately describes