Silver is the best conductor of electricity. It has a conductivity of 62.5 x 10^6 S/m, which is more than twice that of copper (58.5 x 10^6 S/m). Iron has a conductivity of 10.0 x 10^6 S/m, and carbon has a conductivity of 3.5 x 10^3 S/m.
Silver is a good conductor of electricity because it has a high number of free electrons. Free electrons are electrons that are not bound to any particular atom. They are able to move freely through the material, carrying an electric current.
Copper is also a good conductor of electricity, but it is not as good as silver. This is because copper has fewer free electrons than silver.
Iron is a good conductor of electricity, but it is not as good as copper or silver. This is because iron has more impurities than copper or silver.
Carbon is a poor conductor of electricity. This is because carbon has very few free electrons.