Which has maximum number of equivalent per mole of the oxidant?

Explanation

To solve the problem of determining which oxidant has the maximum number of equivalents per mole, we can follow these steps:

### Step 1: Understand the Concept of Equivalent Weight
Equivalent weight is defined as the molecular weight divided by the change in oxidation state. The formula is:
\[ \text{Equivalent Weight} = \frac{\text{Molecular Weight}}{\text{Change in Oxidation State}} \]

### Step 2: Identify the Oxidants and Their Molecular Weights
The given options are:
- A: Zinc (Zn)
- B: Silver (Ag)
- C: Magnesium (Mg)
- D: Iodine (I)

We need to find the molecular weights of these elements:
- Zinc (Zn) = 65.38 g/mol
- Silver (Ag) = 107.87 g/mol
- Magnesium (Mg) = 24.31 g/mol
- Iodine (I) = 126.90 g/mol

### Step 3: Determine the Change in Oxidation State for Each Oxidant
Next, we need to analyze the change in oxidation states for each oxidant:

1. **Zinc (Zn)**: Typically goes from 0 to +2 (Change = 2).
2. **Silver (Ag)**: Typically goes from 0 to +1 (Change = 1).
3. **Magnesium (Mg)**: Typically goes from 0 to +2 (Change = 2).
4. **Iodine (I)**: In the reaction \( IO_3^- \rightarrow I_3^- \):
- Oxidation state of I in \( IO_3^- \): Let it be \( x \).
\[ x + 3(-2) = -1 \implies x = +5 \]
- Oxidation state of I in \( I_3^- \): 0 (as it is in elemental form).
- Change in oxidation state = \( 5 - 0 = 5 \).

### Step 4: Calculate the Equivalent Weights
Using the formula for equivalent weight, we can calculate:

1. **Zinc (Zn)**:
\[ \text{Equivalent Weight} = \frac{65.38}{2} = 32.69 \]

2. **Silver (Ag)**:
\[ \text{Equivalent Weight} = \frac{107.87}{1} = 107.87 \]

3. **Magnesium (Mg)**:
\[ \text{Equivalent Weight} = \frac{24.31}{2} = 12.155 \]

4. **Iodine (I)**:
\[ \text{Equivalent Weight} = \frac{126.90}{5} = 25.38 \]

### Step 5: Compare the Equivalent Weights
Now, we compare the equivalent weights calculated:
- Zinc: 32.69
- Silver: 107.87
- Magnesium: 12.155
- Iodine: 25.38

### Conclusion
The oxidant with the maximum number of equivalents per mole is **Silver (Ag)** with an equivalent weight of 107.87.