Answer: The Ca(OCl)Cl releases nascent oxygen which oxidises the colouring matter.
- A It acts as a reducing agent that adds hydrogen to the dye's chromophore
- B The Ca(OCl)Cl releases nascent oxygen which oxidises the colouring matter
- C It simply dissolves the dye molecules away into the surrounding solution
- D It is mildly basic and chemically neutralises the acidic dye structure
Correct answer: B. The Ca(OCl)Cl releases nascent oxygen which oxidises the colouring matter
Explanation: Bleaching powder [Ca(OCl)Cl] releases hypochlorite (OCl⁻) in water; this produces nascent oxygen which oxidises and destroys the coloured compounds, causing decolourisation.
Electron transfer in a redox reaction: zinc loses electrons (oxidised, acts as reducing agent) and copper(II) ions gain those same electrons (reduced, acts as oxidising agent).
Concept context
Master electron transfer in chemistry: assign oxidation states, balance half-reactions, identify oxidising and reducing agents, and connect redox to everyday reactions.