What is the magnitude of the force between a charge of 5.35uC and another with a charge of 1.25uC separated by 8.0 cm?

If a weighted, air-filled balloon sinks in a lake, it will a. be buoyed up with constant force while sinking b. probably sink to the bottom and probably rise later c. sink until it reaches equilibrium and then remain at constant depth d. always sink to the bottom e. none of the above