Explain giving reasons :
Cause of brownian movement.

Explanation

**Step-by-Step Solution:**

1. **Definition of Brownian Movement**: Brownian movement refers to the random and erratic motion exhibited by small particles suspended in a fluid (liquid or gas). This motion is observable under a microscope and is a characteristic behavior of colloidal particles.

2. **Nature of Colloidal Particles**: Colloidal particles are typically small in size (ranging from 1 nanometer to 1 micrometer) and are dispersed in a continuous medium (the dispersion medium).

3. **Bombardment by Molecules**: The primary cause of Brownian movement is the continuous bombardment of these colloidal particles by the molecules of the dispersion medium. These molecules are in constant motion due to thermal energy, colliding with the particles.

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