Answer:
A. The complete balanced chemical equation, including phase labels, for the reaction is:
BaCl2 (aq) + K2O (aq) → BaO (s) + 2KCl (aq)
B. The type of reaction that has occurred is a double displacement or metathesis reaction. In this reaction, the barium cations (Ba2+) and potassium anions (K+) exchange partners, resulting in the formation of solid barium oxide (BaO) and aqueous potassium chloride (KCl).
C. The indicator that tells you a chemical reaction has occurred is the formation of a solid precipitate. In this reaction, the solid barium oxide (BaO) that forms is a clear indication that a chemical reaction has occurred. Additionally, the fact that the reactants are aqueous and the products include both a solid and an aqueous solution also indicates a chemical reaction has taken place.