[SEE DIAGRAM] [A] colourless salt --(KOH, Δ)--> [B] gas (gives white fumes with HCl) [A] colourless — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Step 1: Separation of iron(III) hydroxide from aluminium hydroxide relies on their difference in amphoteric character. Step 2: Al(OH)3 is amphoteric and dissolves in excess sodium hydroxide (NaOH) to form soluble sodium aluminate (Na[Al(OH)4]), whereas Fe(OH)3 is purely basic and remains insoluble. Step 3: Therefore, adding NaOH solution successfully separates them by dissolving only Al(OH)3, leaving Fe(OH)3 as a precipitate, which matches option (c).