For the preparation of bao2, we first prepare bacl2 by this reaction [baco3+hcl=bacl2++co2+h2o]after product the (bacl2) then we reacion the bacl2 with h2o2 to product the bao2why we do not use the bacl2 when we have in lab, we preparea fresh bacl2 to prepare bao2? ?

Chemical reaction: BaCl₂ + H₂O₂ → BaO₂ + 2HCl.
Fresh barium chloride does not contain another substances (impurities) like barium chloride stored in container. Hydrogen peroxide is very reactive and with some cations and anions gives oxygen and water instead of peroxide.

D. is the answer hope that you