Sodium cannot be obtained by the electrolysis of aqueous solution of `NaCl` using `Pt` electrodes.

Options

A. Sodium liberated reacts with water to produce `NaOH+H_(2)`
B. Sodium being more electropositive than hydrogen, `H_(2)` is liberated at cathode and not sodium
C. Electrolysis cannot take place with brine solution.
D. Brine is neutral in nature.

Answer

To understand why sodium cannot be obtained by the electrolysis of an aqueous solution of NaCl using platinum electrodes, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Electrolysis**: Electrolysis involves the breakdown of an ionic compound in a molten state or in solution by passing an electric current through it. In this case, we are looking at the electrolysis of an aqueous solution of sodium chloride (NaCl).

2. **Identifying the Ions**: In an aqueous solution of NaCl, the compound dissociates into sodium ions (Na⁺) and chloride ions (Cl⁻). Additionally, water (H₂O) also dissociates into hydrogen ions (H⁺) and hydroxide ions (OH⁻).

3. **Reduction Potentials**: To determine which species will be reduced at the cathode, we need to look at the standard reduction potentials:
- The reduction potential of Na⁺ to Na is -2.71 V.
- The reduction potential of H⁺ to H₂ is 0 V.

4. **Comparing Reduction Potentials**: Since the reduction potential for H⁺ (0 V) is higher than that of Na⁺ (-2.71 V), it indicates that H⁺ is more likely to be reduced than Na⁺. Therefore, at the cathode, the reaction that will occur is the reduction of H⁺ to form hydrogen gas (H₂) instead of the reduction of Na⁺ to form sodium metal (Na).

5. **Conclusion**: As a result, during the electrolysis of an aqueous NaCl solution, hydrogen gas is liberated at the cathode instead of sodium metal. This is why sodium cannot be obtained from the electrolysis of aqueous NaCl using platinum electrodes.

### Final Answer:
Sodium cannot be obtained by the electrolysis of aqueous NaCl using platinum electrodes because hydrogen ions (H⁺) are preferentially reduced to hydrogen gas (H₂) instead of sodium ions (Na⁺) being reduced to sodium metal (Na).