MHT CET202522 Apr 2025Evening ShiftChemistryChemical Bonding and Molecular StructureActual
Identify isoelectronic pair from following.
Options
- ANe and O ⁻⁻
- BCl ⁻ and Ca
- CAr and F ⁻
- DK ⁺ and Al ⁺³
Correct answer
A. Ne and O ⁻⁻
Step-by-step solution
Isoelectronic species are those with identical electron counts. Option A: Neon (Ne) with Z = 10 has 10 electrons. Oxygen ion O ⁻⁻ has 2 extra electrons, giving 8 + 2 = 10 electrons. They are isoelectronic. Option B: Chloride ion Cl ⁻ has 17 + 1 = 18 electrons; calcium (Ca) with Z = 20 has 20 electrons. Option C: Argon (Ar) with Z = 18 has 18 electrons; fluoride ion F ⁻ has 9 + 1 = 10 electrons. Option D: Potassium ion K ⁺ has 19 - 1 = 18 electrons; aluminum ion Al ⁺³ has 13 - 3 = 10 electrons. Only Ne and O ⁻⁻ shar