CDS 2026 (I) General Knowledge, question 82

Topic: Geography

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Q82

Consider the following statements regarding ocean currents :

  1. Difference in water density is the main cause for the formation of ocean currents.

  2. Density of water depends on temperature, salinity and pressure.

  3. As a rule, ocean waters move from areas of higher density to areas of lower density as a current.

Which of the statements given above is/are correct ?

  1. (a) 1 and 2 only
  2. (b) 1 only
  3. (c) 1, 2 and 3
  4. (d) 2 and 3 onlyCorrect answer

Solution.

Answer: (d) 2 and 3 only

  1. Statement 1 is wrong: surface ocean currents are driven mainly by the planetary winds and the Earth's rotation; density differences drive the slower deep currents.
  2. Statement 2 is correct: seawater gets denser as it gets colder, saltier or is under more pressure.
  3. Statement 3 is correct: dense water sinks and spreads out towards areas of lighter water, which sets up density currents.

Trap: As a rule in statement 3 oversimplifies, since surface water also flows in to replace water that sinks, but it is the standard textbook description of density currents.