The zig-zag motion of colloidal particle is called……………..

Answer

To solve the question, "The zig-zag motion of colloidal particles is called…", we can follow these steps:

### Step 1: Understand the Concept of Colloidal Particles
Colloidal particles are substances that have a size range between 1 nanometer to 1000 nanometers. They are suspended in a medium and exhibit unique properties due to their size.

**Hint:** Recall the size range of colloidal particles and their behavior in a medium.

### Step 2: Identify the Motion of Colloidal Particles
Colloidal particles are not static; they are always in motion. This motion is characterized by a zig-zag pattern, which is a result of their collisions with fast-moving molecules in the surrounding medium.

**Hint:** Think about the factors that contribute to the motion of particles in a colloidal system.

### Step 3: Name the Motion
The zig-zag motion of colloidal particles is specifically known as "Brownian motion." This term was named after the botanist Robert Brown, who first observed this phenomenon in pollen grains suspended in water.

**Hint:** Remember the historical context of the term and who discovered this motion.

### Final Answer
The zig-zag motion of colloidal particles is called **Brownian motion**.

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