The Salinity of the Ocean

Total Questions: 12

1. Which one of the following denotes water salinity gradient? [U.P.P.C.S. (Pre) (Re-Exam) 2015]

Correct Answer: (b) Halocline
Solution:Halocline is a zone in the oceanic water in which salinity changes rapidly with depth. So, Halocline denotes water salinity gradient.

2. Main Source of Salinity of the Sea is - [53rd to 55th B.P.S.C. (Pre) 2011]

Correct Answer: (b) Land
Solution:Main source of the salinity of sea water is the land. While rivers bring various types of salt contents towards the sea, other factors which regulate the salinity of the sea are evaporation, wind, river water, rain, oceanic currents and the volcanos etc. Average salinity of the sea is about 35‰.

3. Which one of the following salts contributes maximum to the salinity of sea water: [U.P.P.C.S. (Pre) 2000]

Correct Answer: (d) Sodium chloride
Solution:In 1884, during Challenger expedition, William Dittmar produced a report about the chemistry of sea water. He revealed in the report that there are 47 types of salts present in the sea water among which 7 are most prominent. These are as follows –
SaltSalinity (‰)Percentage (%)
Sodium Chloride27.21377.8
Magnesium Chloride3.80710.9
Magnesium Sulphate1.6584.7
Calcium Sulphate1.2603.6
Potassium Sulphate0.8632.5
Calcium Carbonate0.1230.3
Magnesium Bromide0.0760.2

Notably percentage of average salinity in oceans is 35‰ and Sodium Chloride, plays major role in the salinity of the sea.

4. The highest salinity is found in : [U.P.P.C.S. (Pre) 1995]

Correct Answer: (d) Lake Van in Turkey
Solution:Among the lakes and seas given in the question, Van lake of Turkiye has maximum salinity which is 330%
Salinity in the Dead Sea = 238%
Salinity in the Red Sea = 36-41%
Salinity in Great Salt Lake = 220%

5. The highest amount of salinity is found in - [M.P.C.S. (Pre) 2015, Uttarakhand P.C.S. (Mains) 2006]

Correct Answer: (d) Dead Sea
Solution:Among the lakes and seas given in the question, Van lake of Turkiye has maximum salinity which is 330%
Salinity in the Dead Sea = 238%
Salinity in the Red Sea = 36-41%
Salinity in Great Salt Lake = 220%

6. Water of which one of the following seas is most saline? [Uttarakhand P.C.S. (Pre) 2002. U.P.P.C.S. (Pre) 1998]

Correct Answer: (c) Mediterranean Sea
Solution:Among the lakes and seas given in the question, Van lake of Turkiye has maximum salinity which is 330%
Salinity in the Dead Sea = 238%
Salinity in the Red Sea = 36-41%
Salinity in Great Salt Lake = 220%

7. World's most saline Ocean/Lake is – [R.A.S./R.T.S. (Pre) 1997]

Correct Answer: (d) Lake Van
Solution:Among the lakes and seas given in the question, Van lake of Turkiye has maximum salinity which is 330%
Salinity in the Dead Sea = 238%
Salinity in the Red Sea = 36-41%
Salinity in Great Salt Lake = 220%

8. Which of the following Sea has the highest salinity? [U.P.P.C.S. (Pre) 2012]

Correct Answer: (c) Red Sea
Solution:Red Sea has the highest salinity (36 to 41‰). In the above options, the Mediterranean Sea is also a Sea with a salinity of 37 to 39‰. The salinity of the Dead Sea is more than that of the Red Sea and the Mediterranean Sea but it is considered as a lake.

Caspian sea is also a lake. If all the options in the question are considered as the sea, Dead Sea has the highest salinity and would be saltiest among them.

9. When the density in the sea increases, then – [U.P.P.C.S. (Pre) 1990]

Correct Answer: (e) only salinity increases
Solution:If the density of water increases in the sea, it indicates that there is increase in salinity i.e., with the increase in ocean salinity, its density also increases. The distribution of salinity is divided into two types namely horizontal and vertical.

No specific law has been formulated yet regarding the vertical distribution of salinity in the ocean. At some places, salinity increases with increase in depth while at some places it decreases with increase in depth.

10. Where is Great Salt Lake located? [Uttarakhand U.D.A./L.D.A. (Mains) 2006, 2007]

Correct Answer: (b) U.S.A.
Solution:The Great Salt Lake is located in Utah province of the United States of America. The salinity of this lake is 220‰.