The Salinity of the Ocean

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

(a) Thermocline
(b) Halocline
(c) Pycnocline
(d) Chemocline

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]

(a) Rivers
(b) Land
(c) Wind
(d) Ash ejected from the Volcano

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]

(a) Calcium sulphate
(b) Magnesium chloride
(c) Magnesium sulphate
(d) Sodium chloride

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 –

Salt	Salinity (‰)	Percentage (%)
Sodium Chloride	27.213	77.8
Magnesium Chloride	3.807	10.9
Magnesium Sulphate	1.658	4.7
Calcium Sulphate	1.260	3.6
Potassium Sulphate	0.863	2.5
Calcium Carbonate	0.123	0.3
Magnesium Bromide	0.076	0.2

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]

(a) Dead sea
(b) Red sea
(c) Great Salt Lake in the U.S.A.
(d) Lake Van in Turkey

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]

(a) Pacific Ocean
(b) Indian Ocean
(c) Mediterranean Sea
(d) Dead Sea

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]

(a) Baltic Sea
(b) Black Sea
(c) Mediterranean Sea
(d) Red Sea

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]

(a) Caspian Sea
(b) Great Salt Lake
(c) Dead Sea
(d) Lake Van

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]

(a) Caspian Sea
(b) Mediterranean Sea
(c) Red Sea
(d) Dead Sea

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]

(a) Salinity and depth decreases.
(b) Salinity increases but depth decreases.
(c) Both salinity and depth increases.
(d) Salinity decreases and depth increases.
(e) only salinity increases

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]

(a) Iran
(b) U.S.A.
(c) India
(d) Turkey

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‰.

The Salinity of the Ocean

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

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

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

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

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

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]

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

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

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

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

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