Assertion (A) : `EA` of `O` is less than that of `F` but greater than that of `N`.
Reason (R ): `IE` is as follows: `N gt O gt F`.

Options

A. If both Assertion (A) and (R ) are correct and Reason (R ) is the correct explanation of Assertion (A).
B. If both (A) and (R ) are correct but (R ) is not the correct explanation for (A).
C. If (A) is correct but (R ) is not correct.
D. If (A) and (R ) are correct

Explanation

To solve the question, we will analyze both the assertion (A) and the reason (R) provided.

### Step 1: Understanding Electron Affinity (EA)
- **Definition**: Electron affinity is the amount of energy released when an electron is added to a neutral atom in the gaseous state to form a negative ion.
- **Trend**: Generally, electron affinity increases across a period from left to right due to increasing nuclear charge, which attracts electrons more strongly.

### Step 2: Analyzing the Assertion (A)
- **Assertion**: "EA of O is less than that of F but greater than that of N."
- **Analysis**:
- **Fluorine (F)**: Has the highest electron affinity because it has seven valence electrons and needs one more to achieve a stable octet.
- **Oxygen (O)**: Has six valence electrons and thus has a strong attraction for an additional electron, but less than fluorine.
- **Nitrogen (N)**: Has five valence electrons and is less eager to gain an electron compared to oxygen.
- **Conclusion**: The assertion is correct: EA(O) < EA(F) and EA(O) > EA(N).

### Step 3: Understanding Ionization Energy (IE)
- **Definition**: Ionization energy is the energy required to remove an electron from a neutral atom in the gaseous state to form a positive ion.
- **Trend**: Ionization energy generally increases across a period due to increasing nuclear charge.

### Step 4: Analyzing the Reason (R)
- **Reason**: "IE is as follows: N > O > F."
- **Analysis**:
- The correct trend for ionization energy is actually: F > O > N.
- Fluorine has the highest ionization energy because it is close to achieving a full octet and does not want to lose an electron.
- Oxygen has a higher ionization energy than nitrogen because it has a higher nuclear charge, making it harder to remove an electron from oxygen than from nitrogen.
- **Conclusion**: The reason provided is incorrect.

### Final Conclusion
- The assertion is correct, but the reason is incorrect. Therefore, the correct answer is that the assertion is true, but the reason is false.