1st question: A mixture is when the components of a mixture can be easily separated and that the components each keep their original properties.
2nd question:A phase is any part of a sample that has a uniform composition and properties.By definition, a pure substance or a homogeneous mixture consists of a single phase. A heterogeneous mixture consists of two or more phases. When oil and water are combined, they do not mix evenly, but instead form two separate layers.
Heterogeneous mixtures are not uniform in composition. Examples would be wood or blood. Homogeneous mixtures are uniform through out. Typically you can see through them.