Question

Which of the following represent the correct order of decreasing $I{E}_1$ for Ca, Ba, S, Se and Ar?

• A. S < Se < Ca < Ba < Ar
• B. Ba < Ca < Se < S < Ar
• C. Ca < Ba < S < Se < Ar
• D. Ca < S < Ba < Se < Ar

Answer 1

The correct option is

B

Ba < Ca < Se < S < Ar

$I{E}_1$ increases along the period and decreases down the group. Ar has completely filled electrons (stable structure) hence highest $I{E}_1$
Ar >S >Se > Ca >Ba
${18}^{th}$ group ${16}^{th}$ group ${16}^{th}$group II group II group
III period III period IV period IV period VI period