* Pure Substance: A pure substance is a single element or compound with a fixed composition. Water (H2O) is a pure substance.

* Homogeneous Mixture: A homogeneous mixture has a uniform composition throughout. You can't easily distinguish different parts of the mixture. Saltwater is a homogeneous mixture.

* Heterogeneous Mixture: A heterogeneous mixture has a non-uniform composition. You can easily distinguish different parts of the mixture. Sand and water is a heterogeneous mixture.

Cider vinegar is a mixture of:

* Acetic acid: The main ingredient, giving it its sour taste.

* Water: The main solvent, diluting the acetic acid.

* Trace amounts of other compounds: These contribute to the specific flavor and aroma of the vinegar, but they are present in very small amounts.

Since these components are evenly distributed throughout the vinegar, it's considered a homogeneous mixture.