Chromatography of metal salts: Rf and visibility Steps:

• Rf value = distance traveled by compound / distance traveled by solvent; higher Rf indicates less adsorption on paper.
• Group I cations (X) are small, highly charged density, strongly hydrated, adsorb more to cellulose paper, yielding lower Rf.
• Transition cations (Y) have d-electrons, weaker hydration, less adsorption, travel farther, higher Rf.
• Transition salts (Y) often colorless or faint (e.g., some +2 ions), require locating agent like dithizone for detection; Group I visible if flame-colored but spots need agent.

Why C is correct:

• Matches observation where Y shows larger Rf due to mobility and requires locating agent per standard cation separation protocols.

Why the others are wrong:

• A: Wrong Rf assignment; X has smaller Rf.
• B: Wrong on locating agent; X does not require it as much.
• D: Identical to C, but listed separately—likely erroneous.

Not enough information on exact diagram, but C fits typical results. Final answer: C