Answer:
Two objects will have the equal velocities but the forces on both of them will not be equal. The equal velocities of these objects are due to their equal acceleration.
Explanation:
From the newton's equation

so here we can say that velocity does not depends on the mass.
The acceleration of both objects will be same but not the forces because
F = Ma
As the force is depending on the mass so it will not be the same for both objects.
When a liquid or a gas is heated, it expands and becomes less dense, so it rises, while the cooler, denser liquid or gas sinks. (Not sure if this helps but this is what I hit)