Suppose you mix red-tinted oil (density = 0.90 g/mL) with a liter of blue-tinted seawater (density = 1.025 g/mL). After sealing the container, you shake the mixture and then let it settle. What do you
see? Why?

The oil will separate from the seawater when the the mixture is left to settle.

A mixture is a combination of two or more substances that are not chemically combined together.

The red-tinted oil and blue-tinted seawater represents a mixture since the two substances do not combine chemically.

When the oil and seawater are mixed and the mixture is agitated, the oil appears to be all mixed up with the seawater.

After a while, the oil separates from the seawater and floats on top of the seawater because oil is less dense than seawater.

Learn more:

its volumetric flask