Electrostatic force between two charges is called central force.Why?

Electrostatic forces between two point charges is called central force. Why?

Write a relation for the electrostatic force between two point charges placed in a dielectric medium.

General instruction same as in chapter 1. Assertion: The electrostatic force between the plates of a charged isolated capacitro increases, when a dielectric fills whole space between the plates. Reason:The electric field between the plates of a charged isolated capacitor increases, when a dielectric fills the whole space between the plates.

Assertion : The electrostatic force between the plates of a charged isolated capacitor decreases when dielectric fills whole space between plates. Reason : The electric field between the plates of a charged isolated capacitance decreases when dielectric fills whole space between plates.