A cell shorthand notation can be written as A / A$^+$ // B$^{2+}$ /B. The double slash in the notation represents the

Step 1: Analyze the question The question asks what the double slash (//) means in a cell notation such as A / A⁺ // B²⁺ / B.

Step 2: Explain the concept Electrochemical cell notation (cell diagram) follows set conventions:

• A single vertical line (/ or |) shows a phase boundary, for example the solid electrode and its ion solution (solid-liquid interface).
• A double vertical line (// or ||) shows the salt bridge (or porous partition) that connects the two half-cells. It completes the circuit by letting ions flow, and it keeps the solutions electrically neutral.
• The anode (oxidation) half-cell is written on the left, and the cathode (reduction) half-cell on the right.

Step 3: Apply it to the notation A / A⁺ // B²⁺ / B

• A / A⁺: the electrode A is in contact with its ion A⁺. The single slash is a solid-liquid interface. Oxidation happens here: A → A⁺ + e⁻
• //: the salt bridge
• B²⁺ / B: the ion B²⁺ is in contact with electrode B. Reduction happens here: B²⁺ + 2e⁻ → B

Step 4: Eliminate the other options

• A. Electrolyte: the electrolytes are A⁺ and B²⁺, written between the slashes, not the slash itself.
• B. Electrodes: these are A and B, written at the two ends.
• D. Solid-liquid interface: this is shown by the single slash, not the double.

Answer: C. salt bridge

Exam tip: Remember "Single = Surface, Double = Dam (bridge)." One line marks a phase boundary. Two lines mark the salt bridge. Also, the anode is always on the left and the cathode on the right.