Final answer:
Potassium chloride is not considered a mixture because it is a chemically pure compound with a fixed ratio of potassium and chloride ions, unlike emulsion, shaving cream, and tea, which are types of mixtures.
Step-by-step explanation:
Out of the given options, the one that is not considered a mixture is potassium chloride. A mixture consists of two or more substances that are not chemically combined and can have a variable composition. An emulsion such as mayonnaise, is a mixture because it consists of tiny droplets of one liquid dispersed throughout another. Shaving cream is also a mixture; it is a foam made by dispersing gas in a liquid base typically containing soaps or surfactants.
Tea is a homogeneous mixture a solution made up of compounds in water. Potassium chloride, however, is a chemically pure compound consisting only of potassium and chloride ions in a fixed ratio. It is neither a heterogeneous nor a homogeneous mixture.