True.
A mixture is composed of two or more pure substance that are physically combined but are not combined chemically and thus no electrons (of their atoms) are involved.
The primary properties of a mixture include:
1. The components of a mixture are easily separated
2. The components each keep their original properties.
3. The proportion of the components may vary.
There are two main categories of mixtures:
1. Heterogeneous mixtures - substances are not evenly distributed e.g. oil and water mixture
2. Homogeneous mixtures - substances are evenly distributed throughout the mixture e.g. salt water, air.