Question

In pharmaceutical mixing, segregation is most likely to occur when _______

• A. Particles have similar size
• B. Particles differ widely in size and density
• C. Liquid binders are used
• D. Homogenizers are used

Hint:

Segregation in powder mixing increases when particles have large differences in size, shape, or density.

Answer 1

The Correct Option is B

Concept:
Mixing is an important unit operation in pharmaceutics. It is used to produce uniform distribution of ingredients in powders, granules, semisolids, and liquids.

Step 1: Meaning of segregation.
Segregation means separation of mixed particles after or during mixing. It results in non-uniform distribution of ingredients.

Step 2: Cause of segregation.
Segregation commonly occurs when particles differ in:
• Size
• Shape
• Density
• Surface properties

Step 3: Why size and density difference causes segregation.
If particles differ widely in size, smaller particles may settle into spaces between larger particles. If particles differ in density, heavier particles may settle faster than lighter particles. This causes separation and reduces content uniformity.

Step 4: Checking other options.
Particles of similar size usually mix better and show less segregation.
Liquid binders are used in granulation and may reduce powder separation.
Homogenizers are used to improve uniformity, not to promote segregation.

Step 5: Final answer.
Therefore, segregation is most likely to occur when particles differ widely in size and density. \[ \boxed{\text{Particles differ widely in size and density}} \]