👉 A marked fluid, also known as a colloid, is a type of substance where the particles are larger than those in a solution but smaller than those in a suspension, yet they remain dispersed throughout the medium without settling out. These particles are typically between 1 and 1000 nanometers in size, giving the fluid unique properties such as stability over time and resistance to sedimentation. Examples include milk (fat droplets), paint (pigment particles), and blood (red blood cells). The key characteristic of a marked fluid is the size of its particles, which allows them to remain suspended due to Brownian motion and electrostatic repulsion, preventing them from settling like in a suspension.
