What element's valence electrons are located in 5s25p5? A. Tc

B. I

C. Sb

D. Sm

The noble gas that occurs before this valence electron configuration is the element Krypton which has an atomic number of 36. Since there are 7 electron in the valence shell, 2 from the s orbital and 5 from the p-orbital, the unknown element should be a halogen. From the given choices, the halogen is the iodine (I). Thus, the answer is letter B.