5-7 Predict if a precipitation reaction could occur

5-7-1. Precipitation is expected from which mixture?
A. Na₂CO₃(aq) + KNO₃(aq)
B. AgNO₃(aq) + CaCl₂(aq)
C. Neither
D. Both

5-7-2. A student is given two test tubes and is told that one contains NaCl(aq), while the other test tube contain Ba(NO₃)₂(aq). Which precipitating reagent, if added to both test tubes would allow the student to determine their contents?
A. AgNO₃(aq), B. K₂SO₄(aq), C. neither, D. both