Step 1: Understanding the Question:
The question asks for the substance produced at the negative electrode (cathode) when electricity is passed through liquefied (molten) sodium chloride.
Step 2: Key Formula or Approach:
Electrolysis principles:
- Anode (Positive): Oxidation occurs (\(Loss \, of \, e^-\)).
- Cathode (Negative): Reduction occurs (\(Gain \, of \, e^-\)).
Step 3: Detailed Explanation:
1. Molten \(NaCl\) contains only \(Na^+\) and \(Cl^-\) ions.
2. Since it is molten (not aqueous), there is no water involved, so \(H^+\) or \(OH^-\) ions are absent.
3. At the Cathode: The positive sodium ions (\(Na^+\)) migrate to the negative electrode and gain electrons:
\[ Na^+ + e^- \rightarrow Na(s) \]
4. This results in the deposition of Sodium metal.
5. At the Anode: Chloride ions lose electrons to form Chlorine gas:
\[ 2Cl^- \rightarrow Cl_2(g) + 2e^- \]
Step 4: Final Answer:
Sodium metal is obtained at the cathode (B).