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The ions O^2-, F^-, Na^+, Mg^2+ and Al^3+ are isoelectronic. Their ionic radii show:

NEET UG 2003 — Chemistry Physical Chemistry

2003mcqeasy

The ions O2−,F−,Na+,Mg2+\mathrm{O}^{2-}, \mathrm{F}^{-}, \mathrm{Na}^{+}, \mathrm{Mg}^{2+}O2−,F−,Na+,Mg2+ and Al3+\mathrm{Al}^{3+}Al3+ are isoelectronic. Their ionic radii show:

Official previous-year question

Held on 30 Apr 2003 · Verified 9 Jul 2026.

Options

  1. A

    a significant increase from O2−\mathrm{O}^{2-}O2− to Al3+\mathrm{Al}^{3+}Al3+

  2. B

    a significant decrease from O2−\mathrm{O}^{2-}O2− to Al3+\mathrm{Al}^{3+}Al3+

  3. C

    an increase from O2−\mathrm{O}^{2-}O2− to F−\mathrm{F}^{-}F−and then decrease from Na+\mathrm{Na}^{+}Na+to Al3+\mathrm{Al}^{3+}Al3+

  4. D

    a decrease from O2−\mathrm{O}^{2-}O2− to F−\mathrm{F}^{-}F−and then increase from Na+\mathrm{Na}^{+}Na+to Al3+\mathrm{Al}^{3+}Al3+

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