The radii of N, N₃⁻, O and O²⁻ are in the order:

• A) O²⁻ > N₃⁻ > O > N
• B) O²⁻ > N₃⁻ > N > O
• C) N₃⁻ > O²⁻ > N > O
• D) O²⁻ > N₃⁻ > N > O

The radii of atoms and ions can vary significantly based on their charge and electron configuration. In this case, we are comparing the radii of nitrogen (N), the nitride ion (N₃⁻), oxygen (O), and the oxide ion (O²⁻).

Understanding Ionic Radii

When an atom gains electrons, it becomes an anion, which typically increases its radius due to electron-electron repulsion. Conversely, cations are smaller than their neutral atoms because they lose electrons.

Comparing the Elements

• N: Neutral nitrogen has a smaller radius.
• N₃⁻: This ion has gained three electrons, leading to a larger radius.
• O: Neutral oxygen has a smaller radius than nitrogen.
• O²⁻: The oxide ion has gained two electrons, resulting in a larger radius than neutral oxygen.

Arranging the Radii

Based on the above information, the order of radii from largest to smallest is:

• O²⁻ (largest)
• N₃⁻
• N
• O (smallest)

Final Answer

The correct order is O²⁻ > N₃⁻ > N > O, which corresponds to option D.