Which of the followingg statements are true about sodium thiosulphate, `Na_(2)S_(2)O_(3)`?

Options

A. It isused in the estimation of iodine
B. it can give a black precipitate with `AgNO_(3)`
C. it is used to remove the unexposed AgBr from photograhpic films
D. it contains ionic, covalet and coordinate covalent bonds

Answer

To determine which statements about sodium thiosulphate (Na₂S₂O₃) are true, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Analyzing Option 1: "It is used in estimation of iodine."**
- Sodium thiosulphate is indeed used in iodometric titrations, where it acts as a reducing agent to titrate liberated iodine. The reaction involves the reduction of iodine to iodide ions.
- **Conclusion**: This statement is **true**.

2. **Analyzing Option 2: "It can give a black precipitate with AgNO₃."**
- When sodium thiosulphate reacts with silver nitrate (AgNO₃), it forms silver thiosulphate (Ag₂S₂O₃), which is a black precipitate.
- **Conclusion**: This statement is **true**.

3. **Analyzing Option 3: "It is used to remove the unexposed AgBr from photographic films."**
- Sodium thiosulphate is commonly known as a photographic fixer. It dissolves unexposed silver bromide (AgBr) from photographic films, allowing the developed image to be visible.
- **Conclusion**: This statement is **true**.

4. **Analyzing Option 4: "It contains ionic, covalent, and coordinate covalent bonds."**
- Sodium thiosulphate consists of sodium ions (Na⁺) and thiosulphate ions (S₂O₃²⁻). The bond between sodium and thiosulphate is ionic, while the bonds within the thiosulphate ion are covalent. Additionally, there can be coordinate covalent bonds involving the sulfur and oxygen in the thiosulphate ion.
- **Conclusion**: This statement is **true**.

### Final Conclusion:
All the statements regarding sodium thiosulphate (Na₂S₂O₃) are **true**.

---