Which of the following sets of ions represents a collection of isoelectronic species?

Structure of Atom PYQ — JEE Main 2006 · Shift 0 · Q47 with Solution

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Correct answer: C

Definition of isoelectronic species

Isoelectronic species are atoms/ions/molecules having the same number of electrons.
Check each option by calculating number of electrons

Option A: $N_3^-$ , $O^{2-}$ , $F^-$ , $S^{2-}$

For $N_3^-$ : Since it is the azide ion, total electrons are $3\times 7 + 1 = 22$
For $O^{2-}$ : $8+2=10$
For $F^-$ : $9+1=10$
For $S^{2-}$ : $16+2=18$

These do not all have the same number of electrons.

So, A is incorrect.

Option B: $Li^+$ , $Na^+$ , $Mg^{2+}$ , $Ca^{2+}$

$Li^+$ : $3-1=2$
$Na^+$ : $11-1=10$
$Mg^{2+}$ : $12-2=10$
$Ca^{2+}$ : $20-2=18$

These are not all equal.

So, B is incorrect.

Option C: $K^+$ , $Cl^-$ , $Ca^{2+}$ , $Sc^{3+}$

$K^+$ : $19-1=18$
$Cl^-$ : $17+1=18$
$Ca^{2+}$ : $20-2=18$
$Sc^{3+}$ : $21-3=18$

All have 18 electrons.

So, C is correct.

Option D: $Ba^{2+}$ , $Sr^{2+}$ , $K^+$ , $Ca^{2+}$

$Ba^{2+}$ : $56-2=54$
$Sr^{2+}$ : $38-2=36$
$K^+$ : $19-1=18$
$Ca^{2+}$ : $20-2=18$

These are not all equal.

So, D is incorrect.

Final Answer

The set of isoelectronic species is: $\boxed{\text{C}}$

Comparison with stored correct answer

Stored correct answer = C

My derived answer = C

They match.

Structure of Atom question

Structure of Atom question

Option A: $N_3^-$ , $O^{2-}$ , $F^-$ , $S^{2-}$

Option B: $Li^+$ , $Na^+$ , $Mg^{2+}$ , $Ca^{2+}$

Option C: $K^+$ , $Cl^-$ , $Ca^{2+}$ , $Sc^{3+}$

Option D: $Ba^{2+}$ , $Sr^{2+}$ , $K^+$ , $Ca^{2+}$

More from Structure of Atom

Structure of Atom question

Structure of Atom question

Option A: $N_3^-$ , $O^{2-}$ , $F^-$ , $S^{2-}$

Option B: $Li^+$ , $Na^+$ , $Mg^{2+}$ , $Ca^{2+}$

Option C: $K^+$ , $Cl^-$ , $Ca^{2+}$ , $Sc^{3+}$

Option D: $Ba^{2+}$ , $Sr^{2+}$ , $K^+$ , $Ca^{2+}$

More from Structure of Atom

Option A: N3−N_3^-N3−​, O2−O^{2-}O2−, F−F^-F−, S2−S^{2-}S2−

Option B: Li+Li^+Li+, Na+Na^+Na+, Mg2+Mg^{2+}Mg2+, Ca2+Ca^{2+}Ca2+

Option C: K+K^+K+, Cl−Cl^-Cl−, Ca2+Ca^{2+}Ca2+, Sc3+Sc^{3+}Sc3+

Option D: Ba2+Ba^{2+}Ba2+, Sr2+Sr^{2+}Sr2+, K+K^+K+, Ca2+Ca^{2+}Ca2+

More from Structure of Atom

Option A: N3−N_3^-N3−​, O2−O^{2-}O2−, F−F^-F−, S2−S^{2-}S2−

Option B: Li+Li^+Li+, Na+Na^+Na+, Mg2+Mg^{2+}Mg2+, Ca2+Ca^{2+}Ca2+

Option C: K+K^+K+, Cl−Cl^-Cl−, Ca2+Ca^{2+}Ca2+, Sc3+Sc^{3+}Sc3+

Option D: Ba2+Ba^{2+}Ba2+, Sr2+Sr^{2+}Sr2+, K+K^+K+, Ca2+Ca^{2+}Ca2+

More from Structure of Atom

Option A: $N_3^-$ , $O^{2-}$ , $F^-$ , $S^{2-}$

Option B: $Li^+$ , $Na^+$ , $Mg^{2+}$ , $Ca^{2+}$

Option C: $K^+$ , $Cl^-$ , $Ca^{2+}$ , $Sc^{3+}$

Option D: $Ba^{2+}$ , $Sr^{2+}$ , $K^+$ , $Ca^{2+}$

Option A: $N_3^-$ , $O^{2-}$ , $F^-$ , $S^{2-}$

Option B: $Li^+$ , $Na^+$ , $Mg^{2+}$ , $Ca^{2+}$

Option C: $K^+$ , $Cl^-$ , $Ca^{2+}$ , $Sc^{3+}$

Option D: $Ba^{2+}$ , $Sr^{2+}$ , $K^+$ , $Ca^{2+}$