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.

A characteristic of mixtures is they can be separated by physical processes.

Explanation:

This is because a mixture is a substance made up of two or more different substances which have been mixed together physically. If they can be physically combined, they can be physically separated.

answer

fusion: the energy source of stars. the energy released from the collapse of the gas into a protostar causes the center of the protostar to become extremely hot. when the core is hot enough, nuclear fusion commences. fusion is the process where two hydrogen atoms combine to form a helium atom, releasing energy.

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