GATE 2021 BT – Question 38
Match P centrifugation, Q dialysis, R solvent extraction and S ultrafiltration to: 1 density, 2 diffusivity, 3 size, 4 solubility.
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Correct answer: (D) P-1,Q-2,R-4,S-3
Explanation
Each downstream-processing method separates molecules by a physical property.
- **P. Centrifugation:** separates by **density** (the heavier particles sediment). P-1.
- **Q. Dialysis:** small molecules move through a semipermeable membrane by diffusion, so it uses differences in **diffusivity**. Q-2.
- **R. Solvent extraction:** a compound moves into the phase in which it is more **soluble**. R-4.
- **S. Ultrafiltration:** a membrane holds back molecules larger than its pores, so it separates by **size**. S-3.
Match: **P-1, Q-2, R-4, S-3** (option D).