Find the number of metals which are commercially reduced by carbon reduction method from the given metals :
`Ag, Cr, Mn, Sn, Zn, Fe`.

Explanation

To determine the number of metals that are commercially reduced by the carbon reduction method from the given list of metals (Ag, Cr, Mn, Sn, Zn, Fe), we will analyze each metal based on its reactivity and reduction method.

### Step-by-Step Solution:

1. **Identify the Metals**: The metals provided are:
- Silver (Ag)
- Chromium (Cr)
- Manganese (Mn)
- Tin (Sn)
- Zinc (Zn)
- Iron (Fe)

2. **Understand Carbon Reduction Method**: The carbon reduction method is typically used for metals that are less electropositive than carbon. This method involves heating the metal oxide with carbon (usually in the form of coke) to reduce the metal from its oxide.

3. **Analyze Each Metal**:
- **Silver (Ag)**: Silver is a noble metal and is not typically reduced using carbon. It is usually extracted from its ores through other methods.
- **Chromium (Cr)**: Chromium is more reactive and is not reduced by carbon. It is usually extracted from chromite ore using other methods.
- **Manganese (Mn)**: Manganese can be reduced using carbon. It is commonly extracted from manganese dioxide (MnO2) using carbon.
- **Tin (Sn)**: Tin can be reduced by carbon, but it is often extracted using other methods such as electrolysis or using more reactive metals.
- **Zinc (Zn)**: Zinc is commonly reduced using carbon from zinc oxide (ZnO) in a blast furnace.
- **Iron (Fe)**: Iron is also reduced using carbon from iron oxide (Fe2O3 or Fe3O4) in a blast furnace.

4. **Count the Metals Reduced by Carbon**: From the analysis:
- Manganese (Mn) - Yes
- Zinc (Zn) - Yes
- Iron (Fe) - Yes
- Silver (Ag) - No
- Chromium (Cr) - No
- Tin (Sn) - Not typically reduced by carbon

5. **Final Count**: The metals that are commercially reduced by the carbon reduction method are Manganese, Zinc, and Iron. Therefore, the total number of metals is **3**.

### Conclusion:
The number of metals that are commercially reduced by the carbon reduction method from the given list is **3**.

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