Consider the following statements regarding the density of ocean water: 1. Increasing salinity causes density to decrease. 2. High salinity seawater generally sinks below lower salinity water. 3. Stratification by salinity is never observed in oceans. Which of the statements given above is/are correct?

The correct option is 2 only Explanation The density of ocean water is a function of temperature, salinity, and pressure. Variations in these properties determine the vertical stability and movement of water masses, leading to the layering or stratification of the ocean. Statement-wise Analysis - Statement 1 is Incorrect: Salinity represents the total amount of dissolved salts in seawater. Dissolved salts add mass to the water. Therefore, water with higher salinity is denser than water with lower salinity (assuming temperature remains constant). Due to this density difference, high-salinity water tends to sink below lower-salinity water. - Statement 2 is Correct: There is a direct positive relationship between salinity and density. Increasing salinity adds dissolved solids, which increases the mass per unit volume. Consequently, increasing salinity causes density to increase, not decrease. - Statement 3 is Incorrect: Stratification by salinity is frequently observed in oceans. The ocean is vertically structured into layers based on density. A distinct layer known as the halocline exists where salinity changes rapidly with depth. This stratification is crucial for ocean circulation and stability. Key Takeaway: Seawater density increases with higher salinity and lower temperature. This density variance drives vertical currents and results in the stratification of ocean waters.

NCERT Class 11 Geography — Chapter 1: Water (Oceans)

mcqmedium

Consider the following statements regarding the density of ocean water:

Increasing salinity causes density to decrease.
High salinity seawater generally sinks below lower salinity water.
Stratification by salinity is never observed in oceans.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

A1, 2 and 3
B1 and 3 only
C2 only
D1 only

Did you get this right?

Solution

The correct option is

2 only

Explanation

The density of ocean water is a function of temperature, salinity, and pressure. Variations in these properties determine the vertical stability and movement of water masses, leading to the layering or stratification of the ocean.

Statement-wise Analysis

Statement 1 is Incorrect: Salinity represents the total amount of dissolved salts in seawater. Dissolved salts add mass to the water. Therefore, water with higher salinity is denser than water with lower salinity (assuming temperature remains constant). Due to this density difference, high-salinity water tends to sink below lower-salinity water.
Statement 2 is Correct: There is a direct positive relationship between salinity and density. Increasing salinity adds dissolved solids, which increases the mass per unit volume. Consequently, increasing salinity causes density to increase, not decrease.
Statement 3 is Incorrect: Stratification by salinity is frequently observed in oceans. The ocean is vertically structured into layers based on density. A distinct layer known as the halocline exists where salinity changes rapidly with depth. This stratification is crucial for ocean circulation and stability.

Key Takeaway: Seawater density increases with higher salinity and lower temperature. This density variance drives vertical currents and results in the stratification of ocean waters.

Your note

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The correct option is

2 only

Explanation

Statement-wise Analysis

Statement 1 is Incorrect: Salinity represents the total amount of dissolved salts in seawater. Dissolved salts add mass to the water. Therefore, water with higher salinity is denser than water with lower salinity (assuming temperature remains constant). Due to this density difference, high-salinity water tends to sink below lower-salinity water.
Statement 2 is Correct: There is a direct positive relationship between salinity and density. Increasing salinity adds dissolved solids, which increases the mass per unit volume. Consequently, increasing salinity causes density to increase, not decrease.
Statement 3 is Incorrect: Stratification by salinity is frequently observed in oceans. The ocean is vertically structured into layers based on density. A distinct layer known as the halocline exists where salinity changes rapidly with depth. This stratification is crucial for ocean circulation and stability.

Key Takeaway: Seawater density increases with higher salinity and lower temperature. This density variance drives vertical currents and results in the stratification of ocean waters.