A charged metal body is in electrostatic equilibrium. Which of the following statements about it are correct?

• I. The electric field everywhere inside the metal is zero.
• II. The electric potential everywhere inside the metal is zero.
• III. Just outside the surface, the field is normal to the surface and equals σ/ε₀, where σ is the local surface charge density.
• IV. Any excess charge resides on the surface.