Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (a) rice pudding, (b) seawater, (c) magnesium, (d) crushed ice.

- Pure substances: A pure substance is a form of matter that has a constant composition and properties that are constant throughout the sample. It contains only one kind of particle (atoms, ions or molecules). - Mixtures: A mixture is a combination of two or more pure substances in variable proportions such that each substance retains its own chemical identity. - Homogeneous mixture: Also known as a solution, is a mixture in which the components are uniformly distributed throughout the sample on a molecular level. - Heterogeneous mixture: A mixture in which the components are not uniformly distributed throughout the sample, resulting in regions with different properties. Step 2: Analyze and classify each example

Rice pudding is a mixture of different ingredients such as rice, milk, and sugar. The components of the rice pudding are not uniformly distributed, making it a heterogeneous mixture.

Seawater is a mixture of water, salts, and other dissolved substances. These components are evenly distributed at a molecular level, making seawater a homogeneous mixture (solution).

Magnesium is a metallic chemical element and is composed of only magnesium atoms, making it a pure substance.

Crushed ice is a solid form of water, which is composed of water molecules and has a consistent structure and properties throughout the sample, making it a pure substance.