I have to choose one as the greatest of the 4 forces.

gravity - weakest
weak force - no

so it would have to be strong force or electromagnetic force

The strong force is the strongest. The Weak force is not really weak, it is as strong as the electromagnetic force. However, the weak force decays exponentially as a function of distance.

which one opf the 4 forces opposes the electromagnetic force in the nucleus of an atom:

strong force
weak force
gravity

I thought it was stong force

To determine the greatest force among the four fundamental forces (gravity, weak force, strong force, and electromagnetic force), we need to compare their relative strengths.

First, let's look at gravity. Gravity is the weakest force among the four. Its strength is about 10^-38 times weaker than the electromagnetism force.

The weak force is stronger than gravity but still weaker than the strong force and electromagnetic force. However, the weak force predominantly operates within atomic nuclei in processes like radioactive decay, so it's not as relevant in this context.

Now, let's compare the electromagnetic force and the strong force. The electromagnetic force is responsible for interactions between electrically charged particles. It is significantly stronger than gravity, about 10^36 times stronger.

Finally, we have the strong force, also known as the strong nuclear force or strong interaction. It is the force that holds atomic nuclei together. The strong force is the strongest among the four fundamental forces, approximately 100 times stronger than the electromagnetic force.

Based on this comparison, the strong force is the greatest of the four forces. It plays a crucial role in binding protons and neutrons within atomic nuclei and is responsible for the stability of matter as we know it.