Which option is correct?

Options

A. 3rd `I.E.` of `C gt N`
B. 2nd I.E. of `N lt O`
C. 1st I.E. of `F gtO`
D. All of these

Answer

To determine which option is correct regarding ionization energies, we will analyze each statement provided in the question step by step.

### Step 1: Analyze the first statement
**Statement:** Carbon's third ionization energy is more than nitrogen's.

- **Electronic Configuration:**
- Carbon: \(1s^2 2s^2 2p^2\)
- Nitrogen: \(1s^2 2s^2 2p^3\)

- **Ionization Process:**
- For Carbon, removing three electrons (first two from 2s and one from 2p) leads to a configuration of \(1s^2\).
- For Nitrogen, removing three electrons (first two from 2s and one from 2p) leads to a configuration of \(1s^2 2s^2\) (which is stable).

- **Conclusion:** Removing the third electron from Carbon requires more energy due to the stable configuration of Nitrogen after removing three electrons. Therefore, this statement is **correct**.

### Step 2: Analyze the second statement
**Statement:** The second ionization energy of nitrogen is less than that of oxygen.

- **Electronic Configuration:**
- Nitrogen: \(1s^2 2s^2 2p^3\)
- Oxygen: \(1s^2 2s^2 2p^4\)

- **Ionization Process:**
- For Nitrogen, after removing one electron, the configuration becomes \(1s^2 2s^2 2p^2\).
- For Oxygen, after removing one electron, the configuration becomes \(1s^2 2s^2 2p^3\).

- **Stability Consideration:** The half-filled configuration of \(2p^3\) in Nitrogen is more stable than the \(2p^4\) configuration in Oxygen. Thus, removing a second electron from Oxygen is more difficult than from Nitrogen.

- **Conclusion:** This statement is **correct**.

### Step 3: Analyze the third statement
**Statement:** The first ionization energy of fluorine is greater than that of oxygen.

- **Electronic Configuration:**
- Fluorine: \(1s^2 2s^2 2p^5\)
- Oxygen: \(1s^2 2s^2 2p^4\)

- **Ionization Process:**
- For Fluorine, removing one electron leads to \(1s^2 2s^2 2p^4\).
- For Oxygen, removing one electron leads to \(1s^2 2s^2 2p^3\).

- **Trend in Ionization Energy:** As we move from left to right across a period, ionization energy increases due to increasing nuclear charge and decreasing atomic size.

- **Conclusion:** The first ionization energy of Fluorine is indeed greater than that of Oxygen. Thus, this statement is **correct**.

### Final Conclusion
Since all three statements are correct, the correct option is:
**Option 4: All of these are correct.**

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