Which Ion Is NOT Isoelectronic (I $\begin{array} { |l | l| } \hline \mathrm { S } & 1 s ^ { 2 } 2 s ^ { 2 } 2 p ^ { 6 } 3 s ^ { 2 } 3 p ^ { 4 }\\\hline \end{array}$

Multiple Choice

Which ion is NOT isoelectronic (i.e.has the same electron configuration) with Ar? The electron configuration of Ar is shown. $\begin{array} { |l | l| } \hline \mathrm { S } & 1 s ^ { 2 } 2 s ^ { 2 } 2 p ^ { 6 } 3 s ^ { 2 } 3 p ^ { 4 }\\\hline \end{array}$

A) Cl^?
B) K⁺
C) Br^?
D) Ca²⁺
E) S^2?