Question

The continuous random motion of colloidal particles is called:

• A. Brownian movement
• B. Zig zag movement
• C. Continuous movement
• D. Tyndall effect

Hint:

Brownian motion is observed in colloidal solutions and explains the erratic movement of particles in the solution.

Answer 1

The Correct Option is A

The continuous random motion of colloidal particles is called: 

• Option 1: Brownian movement - This is the correct answer. Brownian motion refers to the random, continuous movement of colloidal particles due to collisions with molecules of the surrounding medium (such as water). This motion is a characteristic feature of colloidal systems.
• Option 2: Zig zag movement - This term describes a type of movement but does not specifically refer to the random motion of colloidal particles.
• Option 3: Continuous movement - While colloidal particles do exhibit continuous movement, the specific name for their random motion is Brownian motion, not just "continuous movement."
• Option 4: Tyndall effect - This is not a type of motion but refers to the scattering of light by colloidal particles, which makes the path of the light visible. It is unrelated to the random motion of the particles themselves.

Explanation:

The continuous random motion of colloidal particles is called Brownian movement, named after the botanist Robert Brown who first observed this phenomenon. The movement results from the constant bombardment of colloidal particles by the molecules of the surrounding medium, such as water.

Answer 2

This question is really testing whether random collision-driven motion can be told apart from other phenomena that also involve small particles in a fluid. Let's check what each option actually describes.

1. Brownian movement: Water or air molecules are always moving and constantly strike a suspended colloidal particle from all sides. Because these hits never balance out perfectly at every instant, the particle keeps getting nudged in a new, unpredictable direction. This random zig-zag path caused by molecular bombardment is exactly what is being asked about.
2. Zig zag movement: This phrase only describes the shape of the path on paper. It does not name the phenomenon or explain why the particle moves that way, so it is not the technical term being asked for.
3. Continuous movement: This only says that the particle keeps moving, without saying the motion is random or where it comes from. Plenty of things move continuously, a car on a straight road, for instance, without showing this kind of erratic behaviour, so this phrase is too generic.
4. Tyndall effect: This describes light scattering off colloidal particles, which is how we see a visible beam of light passing through a colloid. It is about optics, not about the particles' own motion, so it answers a different question entirely.

The random, ever-changing path caused by molecules striking a suspended particle is specifically named Brownian movement.

So the correct answer is Brownian movement.