The process that occurs when ink molecules turn a glass of water blue is called diffusion.

Here's why:

* Ink is a mixture of pigments or dyes dissolved in a liquid. These pigment molecules are much smaller than the water molecules.

* When ink is added to water, the pigment molecules start to move randomly. They collide with the water molecules and spread out.

* This random movement causes the ink molecules to distribute evenly throughout the water. The result is that the water takes on the color of the ink.

Diffusion is the process of particles moving from an area of high concentration to an area of low concentration. In this case, the ink molecules are initially concentrated in a small area (the drop of ink). They then diffuse throughout the water until they are evenly distributed.