Thank you for reporting, we will resolve it shortly
Q.
When a boat in a river enters the sea water, then it
Mechanical Properties of Fluids
Solution:
Sea water is saltier than river water, and hence it has more density. The buoyant force on boat upwards is given by $V \rho g$ where $V$ is the volume of displaced water and $\rho$ is the density of water. Clearly the buoyant force is more in case of seawater and hence the boat rises when it goes from river to sea.