Iron(II) hydroxide precipitate reveals low R_f spot in chromatography Steps:

• Sodium hydroxide reacts with Fe²⁺(aq) to form Fe(OH)₂ precipitate at the starting line, preventing migration.
• Low migration means R_f of Fe²⁺(aq) is the smaller value, labeled y.
• Fe(OH)₂ precipitate is characteristically green in color.
• Option A correctly assigns y to R_f and green to the precipitate color.

Why A is correct:

• Fe(OH)₂ definition specifies a green precipitate that stays at the origin (R_f ≈ 0 or y), matching the experiment.

Why the others are wrong:

• B: y green - But A is correct; B mismatches the row for gaps.
• C: x red-brown - x is higher R_f (mobile spot); red-brown is Fe(OH)₃ color, not Fe(OH)₂.
• D: y green - Duplicate of B; incorrect row assignment.

Final answer: A