(Originais Teachy 2024) - Question Hard of Chemistry

During a practical laboratory class, students were challenged to differentiate between pure substances and mixtures and to recognize the importance of physical and chemical properties in the characterization of matter. For this purpose, they were given five samples labeled with codes A, B, C, D, and E, without any additional information about their composition. After conducting a series of tests, the students observed that, when adding a specific reagent, sample A released gas, sample B changed color, sample C formed a precipitate, sample D did not react to any reagent addition, and sample E dissolved completely in water. Based on these results, explain: (1) How each of the observations made by the students (gas release, color change, precipitate formation, non-reactivity, and dissolution in water) can be used to distinguish between a pure substance and a mixture. (2) Considering the definitions of homogeneous and heterogeneous mixtures, identify which samples can be classified in each category, justifying your answer based on the observations made.