(B) is identified by the characteristic colour of the flame. (A) and (B) are respectively :

An inorganic halide (A) reacts with water to form two acids (B) and (C). (A) also reacts with NaOH to form two salts (D) and (E) which remain in solution. The solution gives white precipitate with both AgNO₃ and BaCl₂ solutions respectively. (A) is a useful organic reagent. The compound (A) is