Idea of chromatography

Chromatography separates and purifies compounds based on their different distribution between:

• a stationary phase, and
• a mobile phase.

So the success of purification depends on how the compound interacts with the solvent and stationary phase.

Check each option

A. Solubility of the compound

This is important because a compound must dissolve in the mobile phase to move through the system. Also, its relative solubility affects separation.

Hence, purification is not independent of solubility.

B. Mobility or flow of solvent system

The movement of the solvent is essential in chromatography, since the mobile phase carries the components and helps separate them.

Hence, purification is not independent of solvent flow/mobility.

C. Physical state of the pure compound

Whether the purified compound is finally obtained as a solid or liquid does not govern the chromatographic separation itself. Chromatography depends on adsorption/partition behavior, not on the final physical state of the pure compound.

Hence, purification is independent of this factor.

D. Length of the column or TLC plate

The length affects the extent of separation: a longer column or plate generally allows better resolution.

Hence, purification is not independent of this factor.

Conclusion

The purification of a compound by chromatography is independent of: $\boxed{\text{C: Physical state of the pure compound}}$

Comparison with stored answer

Stored correct answer = C.

My derived answer also = C. So they agree.