Which of the following statement(s) is/are correct?

Options

A. The Chief ore of zinc is cinnabar
B. Mac-Arther's process is used to extract silver
C. `Na_(2)S_(2)O_(3)` is used to remove the unexposed AgBr from the photographic films
D. Nessler's reagent is complex of zinc in +2 oxidation state

Answer

To determine which statements are correct, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement A**: "The chief ore of zinc is cinnabar."
- **Analysis**: Cinnabar is actually the chief ore of mercury, not zinc. The correct chief ore of zinc is zinc blende (ZnS).
- **Conclusion**: This statement is **incorrect**.

2. **Statement B**: "MacArthur's process is used to extract silver."
- **Analysis**: The MacArthur-Forrest process is indeed used for the extraction of silver from its ores. The process involves the formation of a soluble complex with sodium cyanide (NaCN) and the subsequent recovery of silver.
- **Conclusion**: This statement is **correct**.

3. **Statement C**: "Na2S2O3 is used to remove the unexposed AgBr from the photographic films."
- **Analysis**: Sodium thiosulfate (Na2S2O3) is used as a fixing agent in photography to dissolve unexposed silver bromide (AgBr), forming a soluble complex. This confirms that it effectively removes unexposed AgBr.
- **Conclusion**: This statement is **correct**.

4. **Statement D**: "Nessler's reagent is a complex of zinc in +2 oxidation state."
- **Analysis**: Nessler's reagent is actually potassium tetraiodomercurate (K2HgI4), which contains mercury, not zinc. Therefore, this statement is incorrect.
- **Conclusion**: This statement is **incorrect**.

### Final Summary:
The correct statements are **B** and **C**.