Which of the following binary combinations of cations can be rapidly and successfully separated from — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Both $Fe^{3+}$ and $Al^{3+}$ initially form hydroxide precipitates. However, $Al(OH)_3$ is highly amphoteric and completely redissolves in excess $NaOH$ to form the soluble tetrahydroxoaluminate complex ($[Al(OH)_4]^-$). $Fe(OH)_3$ is strictly basic and remains entirely as a reddish-brown insoluble solid, allowing easy filtration.