JEE MAIN - Chemistry (2006 - No. 47)
Which of the following sets of ions represents a collection of isoelectronic species?
N3-, O2-, F-, S2-
Li+, Na+, Mg2+, Ca2+
K+, Cl-, Ca2+, Sc3+
Ba2+, Sr2+, K+, Ca2+
Explanation
Option $$(c)$$ is correct.
In $$\,\,{K^ + }\left( {19} \right)\,\,$$ no. of electrons
$$ = 19 - 1\,\,\,\,\, = 18$$
In $$\,\,{Cl^ - }\left( {17} \right)\,\,$$ no. of electrons
$$ = 17 + 1\,\,\,\,\, = 18$$
In $$\,\,{Ca^ 2+ }\left( {20} \right)\,\,$$ no. of electrons
$$ = 20 - 2\,\,\,\,\, = 18$$
In $$\,\,{Sc^ 3+ }\left( {21} \right)\,\,$$ no. of electrons
$$ = 21 - 3\,\,\,\,\, = 18$$
In $$\,\,{K^ + }\left( {19} \right)\,\,$$ no. of electrons
$$ = 19 - 1\,\,\,\,\, = 18$$
In $$\,\,{Cl^ - }\left( {17} \right)\,\,$$ no. of electrons
$$ = 17 + 1\,\,\,\,\, = 18$$
In $$\,\,{Ca^ 2+ }\left( {20} \right)\,\,$$ no. of electrons
$$ = 20 - 2\,\,\,\,\, = 18$$
In $$\,\,{Sc^ 3+ }\left( {21} \right)\,\,$$ no. of electrons
$$ = 21 - 3\,\,\,\,\, = 18$$
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