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

Step 1: Concept.
Water or air molecules constantly strike a suspended colloidal particle from random directions, and this uneven bombardment pushes the particle along an unpredictable, zig-zag path.

Step 2: Match the term.
This specific random motion caused by molecular collisions is named after the scientist who first observed it, and it is different from the Tyndall effect, which is about light scattering, not motion.

Step 3: Final Answer.
The random motion of colloidal particles is called Brownian movement.

Answer 2

Tracing where the name for this motion comes from settles the question just as well as describing the mechanism does.

1. Brownian movement: This is named after the Scottish botanist Robert Brown, who in 1827 watched pollen grains suspended in water under a microscope and saw them jitter about randomly with no outside force pushing them. The name was given specifically to this random jittering, which is later explained by collisions with water molecules.
2. Zig zag movement: No scientist's name or historical discovery is attached to this phrase. It is a plain description of a path shape, not an established scientific term.
3. Continuous movement: This, too, has no specific discoverer or defined phenomenon behind it. It is just a general description that any moving object would satisfy.
4. Tyndall effect: This is named after John Tyndall, who studied how light scatters off suspended particles, which is a completely separate discovery about optics, not particle motion.

Since the historical discovery of this exact random jittering motion is credited to Robert Brown, the phenomenon carries his name.

So the correct answer is Brownian movement.