Question

The process of mechanically pressing liquid (oil) out of liquid (oil) containing solids is known as:

• A. Extraction
• B. Filtration
• C. Expression
• D. Evaporation

Hint:

If the question mentions pressure or pressing, think Expression. If solvent is used → Extraction.

Answer 1

The Correct Option is C

Concept: Expression is a mechanical separation process in which liquid is removed from a solid-liquid mixture by applying pressure. This process is widely used in oil extraction industries, such as extracting oil from seeds.

Step 1: Understanding expression process.
Expression involves:
• Application of mechanical force or الضغط
• Compression of the material
• Release of liquid trapped within the solid matrix

Step 2: Real-life example.
In oil mills:
• Oilseeds (like groundnut, mustard) are pressed
• Oil is forced out due to pressure
• Residual solid remains as cake

Step 3: Differentiating from other processes.
• Extraction — Uses solvents (like hexane), not mechanical pressure.
• Filtration — Separates solids from liquids using a porous medium.
• Expression — Uses mechanical pressing. Correct.
• Evaporation — Removes liquid by vaporization, not pressure.

Step 4: Key identifying phrase.
The phrase “mechanically pressing” directly indicates expression. Final Conclusion:
The correct term for mechanically pressing liquid out of solids is expression. Hence, option (3) is correct.