The blank force that determines whether or not an object will float is buoyant force.

Here's why:

* Buoyant force is an upward force exerted by a fluid (liquid or gas) that opposes the weight of an immersed object.

* If the buoyant force is greater than the object's weight, the object floats.

* If the buoyant force is less than the object's weight, the object sinks.

Let me know if you'd like more explanation on buoyancy!