Which element in group 6A is not found in compounds with an expanded valence shell?

Question

Quizplus · Accepted Answer

Oxygen is the only element in group 6A that does not commonly form compounds with an expanded valence shell. Its maximum valence is 2, and it tends to form compounds with a complete octet. The other elements in group 6A (selenium, sulfur, tellurium, polonium) can all form compounds with an expanded valence shell, in which they have more than 8 valence electrons around them.

Which Element in Group 6A Is Not Found in Compounds