Among the given statements: 1. Cl2O and ClO2 give nascen oxygen, thus behave as bleaching agent. 2. Salts of OCl− are used as detergents. 3. Oxidation state of Cl in OCl− is (+1), thus it shows disproportionation reaction in acidic medium:
5
ClO−
+1
(5HClO)⟶
2Cl2
[0]
+
ClO3
[+5]
−(HClO3)+2H2O
4. BrO3− does not oxidise in acidic medium. Thus (a) is the correct answer.