EASYMCQ SINGLEJEE Mains ChemistryPhysical ChemistryAtomic StructureIntro
[VMMC 2010] Which of the following pairs is isoelectronic?
0.Ne, Cl
1.Ca²⁺, F⁻
2.Mg²⁺, K⁺
3.N³⁻, Na⁺
Explanation
N³⁻: 7+3 = 10 electrons. Na⁺: 11−1 = 10 electrons. Both have 10 electrons — isoelectronic. (Ca²⁺ has 18 e⁻, F⁻ has 10 e⁻ — NOT isoelectronic.)
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