which of the following group does not represent the isoelectronic species?

Which of the following group does not represent monocot

Which of the following pair(s) represent(s) the isoelectronic species ?

Which set represents isoelectronic species?

Which set represents isoelectronic species ?

Which one of the following consitutes a group of the isoelectronic species?

Which of the following grouping represents a collection of isoelectronic species (At. No : 'Cs=55, Br=35' )