STATEMENT - 1 : Equivalent weight of Mohr salt is `(M)/(4)`, where M is molecular weight.
STATEMENT - 2 : Mohr salt contains only one metallic cation i.e., `Fe^(2+)`
STATEMENT - 3 : Equivalent weight of a salt `= ("Molecular weight")/("Total positive charge")`

Options

A. TTT
B. FTF
C. TFT
D. FFT

Answer

To solve the question, we need to evaluate the three statements regarding Mohr's salt and determine their truth values.

### Step 1: Evaluate Statement 1
**Statement 1:** Equivalent weight of Mohr salt is \( \frac{M}{4} \), where \( M \) is the molecular weight.

- **Explanation:** The equivalent weight of a salt can be calculated using the formula:
\[ \text{Equivalent weight} = \frac{\text{Molecular weight}}{\text{N-factor}} \]
For salts, the N-factor is the total positive charge contributed by the cations in the salt. Mohr's salt (ammonium iron(II) sulfate) has the formula \( \text{NH}_4\text{FeSO}_4 \cdot 6\text{H}_2\text{O} \).

- **Determining the total positive charge:**
- The ammonium ion (\( \text{NH}_4^+ \)) contributes a charge of +1. Since there are two ammonium ions, they contribute \( 2 \times 1 = +2 \).
- The iron ion (\( \text{Fe}^{2+} \)) contributes a charge of +2.

Therefore, the total positive charge is:
\[ +2 \text{ (from NH}_4^+\text{)} + +2 \text{ (from Fe}^{2+}\text{)} = +4 \]

- **Calculating the equivalent weight:**
\[ \text{Equivalent weight} = \frac{M}{4} \]

Thus, **Statement 1 is true.**

### Step 2: Evaluate Statement 2
**Statement 2:** Mohr salt contains only one metallic cation, i.e., \( \text{Fe}^{2+} \).

- **Explanation:** Mohr's salt contains two cations:
- Ammonium ion (\( \text{NH}_4^+ \))
- Iron ion (\( \text{Fe}^{2+} \))

Since there are two cations present, **Statement 2 is false.**

### Step 3: Evaluate Statement 3
**Statement 3:** Equivalent weight of a salt = \( \frac{\text{Molecular weight}}{\text{Total positive charge}} \).

- **Explanation:** This is the same formula we used to calculate the equivalent weight in Statement 1. The equivalent weight is indeed calculated as:
\[ \text{Equivalent weight} = \frac{M}{\text{Total positive charge}} \]

Since this statement accurately reflects the formula, **Statement 3 is true.**

### Conclusion
- **Statement 1:** True
- **Statement 2:** False
- **Statement 3:** True

The correct answer is **Option C: True, False, True.**

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