Answer:
Cyclohexane, water, mercury.
Explanation:
One result of Archimedes' principle is that, in a container, the substance with the highest density will be in the bottom of the container and the substance with the lowest density, will be in the top of the container.
In the test tube with mercury, water and cyclohexane. In the top you will have cyclohexane (Least dense), in the middle will be the water and in the bottom will be mercury.
From the top to the bottom:
Cyclohexane, water, mercury.