Which example is a heterogeneous mixture?

Which example is a heterogeneous mixture?

• A. Uniform salt water
• B. Air
• C. Cereal in milk
• D. Steel

Answer: (C)

Heterogeneous mixtures have a nonuniform composition with visually distinguishable components. Cereal in milk shows two distinct phases—solid cereal pieces and liquid milk—which you can see and separate, so it’s not uniform throughout. The other examples form uniform mixtures or pure substances: saltwater dissolves evenly, giving one consistent composition; air is a uniform mixture of gases at the macroscopic level; steel is a solid alloy with consistent composition throughout. Therefore, cereal in milk is the example that is heterogeneous.

Heterogeneous mixtures have a nonuniform composition with visually distinguishable components. Cereal in milk shows two distinct phases—solid cereal pieces and liquid milk—which you can see and separate, so it’s not uniform throughout. The other examples form uniform mixtures or pure substances: saltwater dissolves evenly, giving one consistent composition; air is a uniform mixture of gases at the macroscopic level; steel is a solid alloy with consistent composition throughout. Therefore, cereal in milk is the example that is heterogeneous.