Identify forces between two objects which are inversely proportional to the square of the distance between them. i. nuclear force between two neutrons; ii. gravitation force btween two celestial bodies; iii. electrostatic force between two electrons. 1. i and ii only 2. ii only 3. none is true. 4. iii only 5. i only 6. all are true. 7. i and iii only 8. ii and iii only

The force between two celestial bodies is a Newtonian gravitational force. 
It is also called Newton's law of universal gravitation. We can write it down mathematically in the following way:

We can see from this formula that gravitational force is inversely proportional to the square of the distance between bodies.
The electrostatic force between two charges is Coulombs force. We can write it down like this: 

This force is also inversely proportional to the square of the distance between interacting particles.
The nuclear force is a little bit more complicated. It can be expressed using the so-called Yukawa potential, which has the following form:

This interaction does not follow the inverse-square law.
The final answer should be 8.