Sodium thiosulphate is prepared by

Options

A. Reducing `Na_(2)SO_(4)` solution with `H_(2)S`
B. Boiling `Na_(2)SO_(4)` solution with S in alkaline medium
C. Neutralising `H_(2)SO_(4)` solution with `NaOH`
D. Boiling `Na_(2)SO_(3)` solution with S in acidie medium

Explanation

To prepare sodium thiosulphate (Na2S2O3), we need to identify the correct method from the given options. Let's analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Sodium Thiosulphate**: Sodium thiosulphate is a chemical compound with the formula Na2S2O3. It is often used in various chemical reactions and applications.

2. **Analyzing the First Option**:
- **Option 1**: Reducing Na2SO4 solution with H2S.
- **Analysis**: Na2SO4 is a neutral salt (formed from a strong acid and a strong base). Neutral salts do not react with H2S in a way that would produce sodium thiosulphate. Therefore, this option is incorrect.

3. **Analyzing the Second Option**:
- **Option 2**: Boiling Na2SO4 with sulfur in alkaline medium.
- **Analysis**: Similar to the first option, Na2SO4 does not react with sulfur in an alkaline medium to form sodium thiosulphate. This option is also incorrect.

4. **Analyzing the Third Option**:
- **Option 3**: Neutralizing H2SO4 solution with NaOH.
- **Analysis**: This is a neutralization reaction between a strong acid (H2SO4) and a strong base (NaOH), which produces Na2SO4 and water, not sodium thiosulphate. Thus, this option is incorrect.

5. **Analyzing the Fourth Option**:
- **Option 4**: Boiling Na2SO3 with sulfur in acidic medium.
- **Analysis**: When sodium sulfite (Na2SO3) is boiled with sulfur in an acidic medium, it reacts to form sodium thiosulphate (Na2S2O3). Therefore, this option is correct.

### Conclusion:
The correct method for preparing sodium thiosulphate is by **boiling Na2SO3 with sulfur in acidic medium**.