Question

Which group of element was missing from Mendeleev's original periodic table?

Answer 1

‘O' group elements are not known at the time of Mendeleeff.
Later they were discovered and placed under O group elements.
Hope it may helps you..

Answer 2

HERE IS UR ANSWER...
grp 18 I. e inert /noble gases grp was missing.... because they were not discovered at that time...

hope this answer helps...