Bleaching powder is prepared by reacting chlorine gas with?

  • A.Quicklime (CaO)
  • B.Slaked lime (Ca(OH)₂)
  • C.Washing soda (Na₂CO₃)
  • D.Gypsum (CaSO₄·2H₂O)

Detailed Solution:

Correct Answer: Slaked lime (Ca(OH)₂)

Bleaching powder is prepared by passing chlorine gas over slaked lime (Ca(OH)₂), not quicklime. The reaction is:

Cl2 + Ca(OH)2 → CaOCl2 + H2O

This product, calcium oxychloride (CaOCl₂), is what we call bleaching powder. The other options are not correct: quicklime (CaO) reacts violently with water, washing soda (Na₂CO₃) would give sodium hypochlorite instead, and gypsum (CaSO₄·2H₂O) does not react with chlorine in this way. Therefore, the correct answer is slaked lime (Ca(OH)₂).

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