Is oil and vinegar salad dressing a heterogeneous mixture homogeneous or pure substance?

* Heterogeneous mixtures have components that are not evenly distributed throughout the mixture. You can see the different parts.

* Homogeneous mixtures have components that are evenly distributed throughout the mixture. You cannot see the different parts.

* Pure substances are made up of only one type of matter and have a fixed composition.

Oil and vinegar don't mix. The oil will float on top of the vinegar, forming distinct layers. You can clearly see the separation, making it a heterogeneous mixture.