Selenium has six valence electrons. what is the valence of selenium

He valence of selenium depends on which compound it is in. Selenium is very similar to sulfur. It may have a valence of 6; example selenium hexafluoride SeF6, selenium trioxide SeO3 
4; example selenium tetrafluoride SeF4, selenium dioxide SeO2 
2; example selenium difluoride SeF2, selenium dichloride SeCl2 
and -2; example hydrogen selenide H2Se

1. o2(g)as a product