In the standard notation for a voltaic cell, the double vertical line "||" represents:
A. a phase boundary
B. gas electrode
C. a wire (metal) connection
D. a salt bridge
Which of the following statements is (are) true for all voltaic (or galvanic) cells?
(I) Reduction occurs at the cathode.
(II) The anode gains mass during discharge (note: this means operation of the cell.)
(III) The voltage is less than or equal to zero.
A. only III
B. only II
C. only I
D. II and III
Answer D. a salt bridge
Answer C. only I. Reduction occurs at the cathode.