Answer the following question given this paragraph: 

The components of a mixture keep their own identity when they combine. Therefore, they usually can be easily separated again. Their different physical properties are used to separate them. For example, oil is less dense than water, so a mixture of oil and water can be separated by letting it stand until the oil floats to the top. Other ways of separating mixtures are shown in Figure below and in the videos below.


Q: The components of what keep their own identity when they combine and can usually be easily separated?


A:
mixture