Question: 

Many students first learning about atomic structure and electricity notice a paradox with respect to the location of all the protons in an atom: despite their electrical charge, they are tightly bound together in a "core" called the nucleus. Based on what you know about electrical charges, explain why this is a paradox, and also what the solution to the paradox is.

Answer:

Paradox: since similar charges tend to physically repel each other, why should protons (all positively charged) cling so tightly together in the nucleus of an atom? Why don't they fly apart from each other due to electrical repulsion?

I'll let you research the answer to this paradox yourself!