Which is a characteristic of mixtures? they are chemically bonded together. they can be classified as pure substances. they have fixed ratios between their components. they can be separated by physical processes.'

They can be separated by physical processes. This problem requires you to simply memorize the definition of a mixture. So let's take a look at the choices and see why one is correct while the other three are wrong. 1. They are chemically bonded together - The definition of a mixture is where "two or more pure substances are combined where each substance retains its individual chemical property." This option isn't correct. 2. They can be classified as pure substances - This option doesn't work either since a mixture has two or more pure substances. 3. They have fixed ratios between their components - Imagine a mixture of salt and flour. You can have a little salt in the mixture or a lot of salt in the mixture. There isn't a fixed ratio, so this is also a bad choice. 4. They can be separated by physical processes - Since the other three options are all obviously false, this is the only possible option. Mind, the separation may not be easy (take a look at the salt and flour mixture used as a demonstration above), but it should be possible.