Question

Which of the following separation processes is/are based on molecular size?

• A. Size-exclusion chromatography
• B. Ion exchange chromatography
• C. Membrane ultrafiltration
• D. Ultracentrifugation

Hint:

Size-exclusion chromatography and ultrafiltration are both methods that directly separate molecules based on their size.

Answer 1

The Correct Option is A, C, D

To determine which separation processes are based on molecular size, let us review each method:

Step 1: Size-exclusion chromatography
This technique separates molecules based on their size. Larger molecules elute faster, while smaller molecules are retained in the column for a longer time. Hence, this is based on molecular size.
Thus, \( \boxed{A} \) is correct.

Step 2: Ion exchange chromatography
Ion exchange chromatography separates ions and polar molecules based on their charge, not size. This method relies on ionic interactions rather than molecular size.
Thus, \( \boxed{B} \) is incorrect.

Step 3: Membrane ultrafiltration
Ultrafiltration is a filtration process that separates molecules based on size by using a semipermeable membrane. Molecules above a certain size will not pass through the membrane, while smaller molecules will. This is based on molecular size.
Thus, \( \boxed{C} \) is correct.

Step 4: Ultracentrifugation
In ultracentrifugation, particles are separated based on their size and density under high centrifugal forces. This process relies on the molecular size of the particles, with larger particles sedimenting faster.
Thus, \( \boxed{D} \) is correct.

Final Answer:
The correct answers are \( \boxed{A}, \boxed{C}, \boxed{D} \).