Final answer:
An ice cube floats higher in salt water due to the increased buoyancy from the solution's higher density, following Archimedes' Principle. A melting glacier on land would cause a greater rise in the lake's water level compared to an iceberg already floating in it. The density difference between salt water and fresh water affects not only floating objects but also biologic entities such as red blood cells and fish. Therefore, the correct option is A.
Step-by-step explanation:
When comparing an ice cube floating in fresh water versus salt water, the ice cube will float higher in salt water due to the difference in density between the two solutions. Saltwater is denser than freshwater because of the dissolved salts, which increases buoyant force as per Archimedes' Principle. According to this principle, the amount of fluid displaced will be equal in weight to the buoyant force applied on the object submerged. Since the salt water has a higher density, the ice cube does not need to displace as much volume to equal its weight, which means more of the ice cube remains above the surface. Conversely, fresh water has a lower density, thus requiring the ice cube to displace more water to obtain the buoyant force necessary to balance its weight, which means the ice cube will be more submerged. Regarding the comparison of a melting iceberg in a lake to a melting glacier on land, it is the glacier that would contribute to a greater rise in the lake's level. This is because the iceberg floating in the lake is already displacing water equal to its weight, and once it melts, the volume of water produced will be approximately equal to the volume of water it displaced. On the other hand, the glacier on land contributes additional water that was not previously in the lake, causing the water level to rise. Archimedes' Principle not only affects buoyancy but also the behavior of various substances in different conditions. For instance, when discussing red blood cells in a hypotonic solution, the cells will swell and possibly burst due to the flow of water into the cells. Similarly, a saltwater fish placed in freshwater would struggle since its cells could take in too much water, disrupting its internal salt balance.