Final answer:
A diamond would sink through water and ether and come to rest on top of the mercury layer in a cylinder due to its density being higher than the former and lower than the latter.
Step-by-step explanation:
The outcome depends on the densities of the diamond and the liquids in the cylinder. Since a diamond is denser than substances like water and ether, but less dense than mercury, it would sink through the less dense liquids and come to rest on top of the mercury layer at the bottom of the cylinder. This outcome aligns with Archimedes' principle, which states that an object will float in a fluid if its density is less than that of the fluid. In this scenario, the buoyant force exerted by the mercury is enough to support the diamond, allowing it to remain on the surface. This demonstrates the interplay between the densities of different substances and their effects on the buoyancy of objects within them. Thus, the correct answer is A. On top of the mercury.