Chemical used as a depressant in separatin ZnS from PbS in froth-floatation process , is

Options

A. NaCN
B. NaCl
C. AgCl
D. All of these

Answer

To solve the question regarding the chemical used as a depressant in separating zinc sulfide (ZnS) from lead sulfide (PbS) in the froth flotation process, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Froth Flotation Process**:
- The froth flotation process is a method used for separating hydrophobic materials from hydrophilic ones. It is commonly used in the mining industry to separate valuable minerals from ore.

2. **Identify the Role of Depressants**:
- In this process, a depressant is a chemical that selectively prevents one of the minerals from floating while allowing the other to float. This is crucial for the separation of different sulfide ores.

3. **Recognize the Specific Ores**:
- In this case, we are focusing on the separation of zinc sulfide (ZnS) from lead sulfide (PbS).

4. **Determine the Depressant Used**:
- According to the information provided, sodium cyanide (NaCN) is used as a depressant in the froth flotation process to separate ZnS from PbS. NaCN selectively allows PbS to float while preventing ZnS from doing so.

5. **Evaluate the Options Given**:
- The options provided are:
1. NaCN
2. NaCl
3. AgCl
4. All of these
- Based on the understanding that NaCN is specifically used as a depressant for this separation, we can conclude that option 1 (NaCN) is the correct answer.

### Final Answer:
The chemical used as a depressant in separating ZnS from PbS in the froth flotation process is **NaCN**.

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