C-12-Q134mediumsingle_mcqBleaching powder is prepared by passing Cl2\mathrm{Cl_2}Cl2 gas through—aCa(OH)2\mathrm{Ca(OH)_2}Ca(OH)2 at 40∘C40^\circ\mathrm{C}40∘CbNaOH\mathrm{NaOH}NaOH at 100∘C100^\circ\mathrm{C}100∘CcNH4OH\mathrm{NH_4OH}NH4OH at 25∘C25^\circ\mathrm{C}25∘CdKOH\mathrm{KOH}KOH at 0∘C0^\circ\mathrm{C}0∘C