A. Molecular geometry and size

B. Molecular composition

C. Molecular phase

D. Molecular formula

Correct Answer: A. Molecular geometry and size

Size exclusion chromatography (SEC) separates solutes based on their hydrodynamic size and molecular geometry as they navigate porous beads—larger molecules elute first, smaller ones later.

Option Analysis

A. Molecular geometry and size (Correct)
SEC uses porous stationary phases where large molecules cannot enter pores (excluded, elute first), while smaller molecules penetrate pores (delayed elution). Separation depends on hydrodynamic radius, not chemical interactions.

B. Molecular composition
Composition determines separation in adsorption/partition chromatography via chemical affinities. SEC is non-interacting; all molecules elute purely by physical size exclusion regardless of composition.​

C. Molecular phase
Invalid term in chromatography context. Phases refer to mobile/stationary systems, not molecular properties. SEC separation ignores phase characteristics.​

D. Molecular formula
Formula indicates atom count but not 3D size/shape. Isomers with identical formulas but different conformations separate differently in SEC by geometry.​

Size exclusion chromatography separates solute molecules based on molecular geometry and size through porous beads—essential for protein purification in biochemistry and GATE Life Sciences.

SEC Mechanism

Large molecules bypass pores (early elution), small molecules enter pores (late elution). No chemical interactions occur; pure size-based sieving provides native protein analysis.

Comparison Table

GATE Applications

Critical for gel filtration questions in molecular biology. Used for aggregate removal, MW estimation, and desalting in protein/nucleic acid purification workflows.