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which statement is an identifying characteristic of a
mixture?
(1) a mixture can consist of a single element.
(2) a mixture can be separated by physical means.
(3) a mixture must have a definite composition by
weight.
(4) a mixture must be homogeneous.

Explanation:

For example, you can separate a mixture of sand and water by pouring it through a coffee filter.

(1) is wrong. A mixture must have at least two components.

(3) is wrong. A mixture can have a any composition depending on the amount of each component.

(4) is wrong. A mixture of sand and water is heterogeneous,

smooth muscle is composed of involuntary muscles found within the walls of organs and structures such as the esophagus, stomach, intestines, and blood vessels. those muscles push materials like food or blood through organs. unlike skeletal muscle, smooth muscle can never be under your control.