Final answer:
Seawater typically has a salinity of about 3.5%, which is crucial for marine life and related to the ocean's pH level suitable for life functions.
Step-by-step explanation:
The percentage range of salinity in seawater typically falls around 3.5%, where seawater is an approximately 3.0% aqueous solution of NaCl by mass with about 0.5% of other salts. Some bodies of water may have higher salinity levels, for instance, sea water that's approximately four times more concentrated than the average would have about 14% salinity due to more salts dissolved in it. The salinity of ocean water is vital for marine life, as it affects their biological processes and is related to the ocean's pH level, which ranges from 7.5 to 8.4, allowing for proper life function.