`Fe + conc. underset((gt80%))(HNO_(3))rarr X` . Then `X` will be

Options

A. `Fe_(2)O_(3)`
B. `FeO`
C. `Fe_(3)O_(4)`
D. None of these

Answer

To solve the question regarding the reaction of iron (Fe) with concentrated nitric acid (HNO3) greater than 80% concentration, we will follow these steps:

### Step 1: Understand the Reaction
When iron is exposed to concentrated nitric acid, a chemical reaction occurs. The concentrated nitric acid is a strong oxidizing agent.

**Hint:** Remember that concentrated nitric acid can passivate metals by forming an oxide layer.

### Step 2: Identify the Product
The reaction of iron with concentrated nitric acid leads to the formation of a protective oxide layer. This layer is typically iron(II,III) oxide, known as magnetite (Fe3O4).

**Hint:** Think about the common oxides of iron and their properties when reacting with strong oxidizers.

### Step 3: Determine the Nature of the Product
The oxide layer that forms on the surface of iron makes it passive, meaning it becomes unreactive. This oxide layer prevents further reaction with the acid.

**Hint:** Consider the implications of passivation in metal reactions, especially with strong acids.

### Step 4: Conclusion
Based on the above steps, the product `X` formed when iron reacts with concentrated nitric acid is Fe3O4 (iron(II,III) oxide).

**Final Answer:** X = Fe3O4

### Summary of Steps:
1. Understand the nature of the reaction between iron and concentrated nitric acid.
2. Identify the product formed, which is an oxide.
3. Recognize the significance of the protective oxide layer that leads to passivation.
4. Conclude that the product is Fe3O4.