Dear Sajid,

Thanks for your question. We really don’t know (yet) why certain fundamental constants (charge, mass, etc.) have certain values. They seemingly need to be this way for us to be here and our universe to exist in its current state, but we have no theory (yet) that predicts their values. This is one goal of a so-called “Theory of Everything”. One could perhaps argue that protons are positively charged and electrons are negatively charged so that they can attract each other to form atoms. Neutrons have no electric charge so that they can help hold the nucleus together via the strong force without creating a repulsive electric force that could break atoms apart.