To determine the correct order of atomic radii for the given elements, we need to analyze each option based on the periodic trends of atomic size.
### Step-by-Step Solution:
**Step 1: Analyze the first option - Sodium (Na), Magnesium (Mg), and Aluminum (Al)**
- **Atomic Numbers**: Na = 11, Mg = 12, Al = 13.
- **Trend**: As we move from left to right across a period in the periodic table, the atomic radius decreases due to an increase in nuclear charge (more protons) which pulls the electrons closer to the nucleus.
- **Conclusion**: The order is Na > Mg > Al. This option is correct.
**Step 2: Analyze the second option - Na⁺, Mg²⁺, and Al³⁺**
- **Charge and Size**: Na⁺ has lost one electron, Mg²⁺ has lost two, and Al³⁺ has lost three electrons.
- **Trend**: As the positive charge increases, the effective nuclear charge increases, leading to a decrease in size. Thus, Na⁺ > Mg²⁺ > Al³⁺.
- **Conclusion**: This option is also correct.
**Step 3: Analyze the third option - I⁻, I, and I⁺**
- **Charge and Size**: I⁻ has gained an electron, I is neutral, and I⁺ has lost an electron.
- **Trend**: When an atom gains electrons (anions), it increases in size due to electron-electron repulsion. Conversely, when it loses electrons (cations), the size decreases due to increased nuclear charge.
- **Conclusion**: The order is I⁻ > I > I⁺. This option is correct as well.
**Step 4: Analyze the fourth option - Nitrogen (N), Helium (He), and Neon (Ne)**
- **Atomic Numbers**: N = 7, He = 4, Ne = 10.
- **Trend**: Helium has the smallest radius because it has only 1s² electrons. Nitrogen has a larger radius than helium but smaller than neon, which has a full outer shell (1s² 2s² 2p⁶).
- **Conclusion**: The correct order is He < N < Ne. This option is incorrect as it states the order incorrectly.
### Final Conclusion:
The correct orders of radii are:
1. Na > Mg > Al (correct)
2. Na⁺ > Mg²⁺ > Al³⁺ (correct)
3. I⁻ > I > I⁺ (correct)
4. He < N < Ne (incorrect)
