What was one important thing that Mendeleev did that proved his periodic table?

i would say b

explanation:

but i think i would need more information than that

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.