When a boat enters the sea from the river?

Correct option is C

• When a boat moves from a river to the sea, it experiences a change in water density. Seawater is denser than river water due to its salt content. According to Archimedes' Principle, a body displaces water equal to its weight, and denser water provides greater buoyant force.
• In river water (less dense), the boat displaces more water and sits lower.
• In seawater (denser), the boat requires less displacement to balance its weight and rises slightly.

• Archimedes’ Principle: Upward buoyant force equals the weight of displaced fluid.
• Seawater Density: About 1.025 g/cm³, higher than river water (1.000 g/cm³).
• Effect of Salinity: Increased salt content raises water density and buoyancy.
• Ships in Seawater: Float higher than in freshwater due to greater buoyant force.

•  It sinks a little → Incorrect. Increased buoyancy in seawater prevents sinking.
• There is no effect → Incorrect. The change in water density directly affects buoyancy.
•  After sinking a little, it comes back to its original position → Incorrect. The boat immediately rises, not after sinking.