Statement-1: `K_(2)CO_(3)` cannot be prepared by Le-blanc method.
Statement-2: Sodium nitrate when heated gives `NO_(2)` gas.
Statement-3: `NaO_(2)` is paramagnetic while `Na_(2)O_(2)` is diamagnetic.

Options

A. FFT
B. FTT
C. TFT
D. TTF

Answer

To analyze the statements provided in the question, we will evaluate each statement one by one and determine their validity based on the principles of chemistry.

### Step 1: Evaluate Statement 1
**Statement 1:** `K2CO3` cannot be prepared by Le-Blank method.

- The Le-Blank method is primarily used to prepare sodium carbonate (`Na2CO3`) from sodium chloride (`NaCl`). The process involves reacting `NaCl` with sulfuric acid (`H2SO4`) to form sodium sulfate (`Na2SO4`), which is then reacted with carbon to produce sodium carbonate.
- However, since potassium (`K`) and sodium (`Na`) are both alkali metals and share similar chemical properties, `K2CO3` can indeed be prepared using a similar method by substituting `KCl` for `NaCl`.
- Therefore, **Statement 1 is false**.

### Step 2: Evaluate Statement 2
**Statement 2:** Sodium nitrate when heated gives `NO2` gas.

- The thermal decomposition of sodium nitrate (`NaNO3`) typically produces sodium nitrite (`NaNO2`) and oxygen (`O2`), not nitrogen dioxide (`NO2`).
- The reaction can be represented as:
\[ 2 \text{NaNO}_3 \rightarrow 2 \text{NaNO}_2 + \text{O}_2 \]
- Since `NO2` is not produced in this reaction, **Statement 2 is false**.

### Step 3: Evaluate Statement 3
**Statement 3:** `NaO2` is paramagnetic while `Na2O2` is diamagnetic.

- Sodium superoxide (`NaO2`) contains unpaired electrons, making it paramagnetic. Paramagnetic substances are attracted to magnetic fields due to the presence of unpaired electrons.
- On the other hand, sodium peroxide (`Na2O2`) has all its electrons paired, resulting in it being diamagnetic. Diamagnetic substances are not attracted to magnetic fields.
- Therefore, **Statement 3 is true**.

### Conclusion
Based on the evaluations:
- Statement 1: False
- Statement 2: False
- Statement 3: True

Thus, the overall answer is **FFT** (False, False, True).