For the following electron configurations choose 3 possible elements (or ions) they may represent

a. 1s2 2s22p6 3s23p6 4s2 3d10 4p6


b. 1s2 2s22p6 3s23p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6


c. [Kr] 5s2 4d10 5p6


d. [Xe]