In the electrolysis of brine, the anode must be carbon because carbon (graphite) is an inert electrode that can conduct electricity and resist the corrosive effects of the chlorine gas produced at

15. In the electrolysis of brine, the anode must be carbon because carbon (graphite) is an inert electrode that can conduct electricity and resist the corrosive effects of the chlorine gas produced at its surface. Other materials might react with chlorine.

The final answer is $\boxed{\text{E chlorine attacks other elements but not carbon}}$.

16. The potential difference established between a metal and its solution when it is dipped into that solution is called the electrode potential.

The final answer is $\boxed{\text{C electrode potential}}$.

17. When a metal is in contact with a one molar solution of its ions at $25^\circ C$ (standard conditions), the potential difference set up is specifically called the standard electrode potential.

The final answer is $\boxed{\text{B standard electrode potential}}$.

18. The standard hydrogen electrode (SHE) is used as the reference electrode, and its electrode potential is defined as exactly zero volts at all temperatures.

The final answer is $\boxed{\text{B zero}}$.