Final answer:
The mixture of KHNO₃, SiO2, and CuSO₄·5H₂O is a heterogeneous mixture, comprised of individually identifiable compounds that do not create a uniform composition when combined.
Step-by-step explanation:
The mixture of KHNO₃, SiO2, and CuSO₄·5H₂O is a heterogeneous mixture. This is because it consists of different substances that do not blend completely to form a uniform composition. Potassium nitrate (KHNO₃) is a compound; silicon dioxide (SiO2) is another compound, often referred to as silica; and copper(II) sulfate pentahydrate (CuSO₄·5H₂O) is yet another compound. When these substances are mixed, their distinct particles can typically be distinguished visually or through microscopic examination, leading to the classification as a heterogeneous mixture.