Sodium thiosulphate is formed when: — p Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: Sodium thiosulfate (Na2S2O3) can be prepared by boiling an aqueous solution of sodium sulfite (Na2SO3) with elemental sulfur: Na2SO3 + S -> Na2S2O3. Step 2: It can also be prepared by the neutralization of unstable thiosulfuric acid (H2S2O3) with sodium hydroxide (NaOH): H2S2O3 + 2NaOH -> Na2S2O3 + 2H2O. Step 3: Since both methods (b) and (c) successfully form sodium thiosulfate, they are both chemically correct answers. We select (b) as the primary industrial and laboratory preparation method.