Answer: Option (d) is the correct answer.
Explanation:
It is known that sea water contains a large amount of common salt, that is, sodium chloride (NaCl). This salt is basic in nature.
Since, it is also known that species which have pH equals to 7 are basic in nature. Species which have pH less than 7 are acidic in nature and species which have pH greater than 7 are basic in nature.
Hence, due to the presence of common salt in sea water its surface is basic in nature.
Therefore, we can conclude that the normal pH of surface sea water is 9.0.