Textbook Problem

Name the noble gas atom that has the same electron configuration as each of the ions in the following compounds.

msp;  $\begin{array}{l}\text{a}.\text{ barium sulfide},\text{ BaS}\\ \text{b}.\text{ strontium fluoride},{\text{ SrF}}_{\text{2}}\\ \text{c}.\text{ magnesium oxide},\text{ MgO}\\ \text{d}.\text{ aluminum sulfide},{\text{ Al}}_{\text{2}}{\text{S}}_{\text{3}}\end{array}$