Final answer:
The average salinity of typical seawater is 3.5%.
Step-by-step explanation:
The average salinity of typical seawater is 3.5%. Seawater is mostly H2O, but about 3.5% of it is dissolved solids, mainly NaCl (salt) and other ions. This high concentration of salts in seawater is what gives it its characteristic taste and makes it different from freshwater.