The reaction of sodium thiosulphate with I2 gives: — p Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: The thermal stability of chlorine oxyacids depends on the oxidation state of the chlorine atom. Step 2: As the number of oxygen atoms increases (from HOCl to HOClO3), the Cl-O bonds gain more double-bond character due to dπ-pπ back-bonding, and the negative charge on the conjugate base is more effectively dispersed by resonance, making the acid more stable. Step 3: Therefore, perchloric acid (HOClO3) is thermally the most stable oxyacid of chlorine, which corresponds to option (a).