The correct statement among the following is:

Options

A. the first ionization energy of `AI` is less than first ionizarion energy of `Mg`.
B. the second ionization energy of `Mg` is greater than second ionization energy of `Na`
C. the first ionization energy of `Na` is less than first ionization energy of `Mg`.
D. the third ionization energy of `Mg` is greater than third ionization energy of `AI`.

Explanation

To solve the question regarding the correct statement about the ionization energies of aluminum, magnesium, and sodium, we will follow these steps:

### Step 1: Understand Ionization Energy
Ionization energy is defined as the amount of energy required to remove an electron from a neutral isolated gaseous atom.

### Step 2: Identify the Electronic Configurations
- **Aluminum (Al)**: The electronic configuration is \( [Ne] 3s^2 3p^1 \).
- **Magnesium (Mg)**: The electronic configuration is \( [Ne] 3s^2 \).
- **Sodium (Na)**: The electronic configuration is \( [Ne] 3s^1 \).

### Step 3: Determine the Trends in Ionization Energy
The general trend for ionization energy is that it increases across a period (from left to right) and decreases down a group (from top to bottom).

- **Magnesium** has a full \( ns^2 \) configuration, which is more stable and requires more energy to remove an electron.
- **Aluminum** has one electron in the \( 3p \) subshell, making it easier to remove compared to magnesium.
- **Sodium** has one electron in the \( 3s \) subshell, which is also easier to remove than magnesium.

### Step 4: Compare the First Ionization Energies
- **First Ionization Energy Order**:
- Magnesium (highest)
- Aluminum (middle)
- Sodium (lowest)

Thus, the first ionization energy of aluminum is less than that of magnesium.

### Step 5: Evaluate the Given Statements
1. **The first ionization energy of aluminum is less than the first ionization energy of magnesium.** (Correct)
2. **The second ionization energy of magnesium is greater than the first ionization energy of aluminum.** (Incorrect)
3. **The first ionization energy of sodium is less than the first ionization energy of magnesium.** (Correct)
4. **The third ionization energy of magnesium is greater than the third ionization energy of sodium.** (Correct)

### Conclusion
The correct statements are:
- The first ionization energy of aluminum is less than that of magnesium.
- The first ionization energy of sodium is less than that of magnesium.
- The third ionization energy of magnesium is greater than that of sodium.

### Final Answer
The correct statement among the options provided is:
1. The first ionization energy of aluminum is less than the first ionization energy of magnesium.

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