Ions with Stable Octet Configuration

Steps:

• Neutral Na has 11 electrons (1s² 2s² 2p⁶ 3s¹); loses 1 to form Na⁺ with 10 electrons (neon configuration, 8 in outer shell).
• Neutral Cl has 17 electrons (1s² 2s² 2p⁶ 3s² 3p⁵); gains 1 to form Cl⁻ with 18 electrons (argon configuration, 8 in outer shell).
• Both ions achieve noble gas stability with 8 valence electrons, per octet rule.
• Compare to options: only B matches this shared electronic property.

Why B is correct:

• Octet rule states stable ions have 8 electrons in outermost shell; Na⁺ and Cl⁻ both fulfill this for chemical inertness.

Why the others are wrong:

• A: Na atoms have 11 protons and ~12 neutrons (varies by isotope), Cl has 17 protons and ~18 neutrons—not more neutrons than protons universally.
• C: NaCl dissolves in water; ions disperse, do not sink as solid.
• D: In molten NaCl electrolysis, Na⁺ migrates to negative cathode, Cl⁻ to positive anode.

Final answer: B