Which of the following pairs of cations cannot be separate by using an NaOH solution? — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Step 1: Precipitation of anions depends on the solubility of their salts with various metal cations. Step 2: Most chlorides, sulfates, and carbonates form insoluble precipitates with several common metal cations (e.g., AgCl, BaSO4, CaCO3). Step 3: All common nitrate salts (NO3-) are highly soluble in water because of the low charge density and favorable hydration/lattice energy of the nitrate ion, making it very difficult to precipitate from aqueous solution. Thus, the correct option is (c).