Answer:
The orange salt ring is the most soluble salt. As water evaporates from seawater, the salinity of the remaining solution increases.
Explanation:
As water evaporates from seawater, the salinity of the remaining solution increases. Different salts become insoluble at different salinities. When a salt becomes insoluble, it precipitates (falls out of) solution and forms crystals. SF Fig. 2.1 identifies some of the salt rings formed when seawater was evaporated from a watch glass. The outer ring, which precipitated out of solution first, is primarily made up of calcium carbonate (CaCO3). Carbonates are the least soluble salts in seawater. The inner ring is primarily made up of potassium (KCl) and magnesium (MgCl2) salts, which are very soluble.
