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1)As the electronic configuration of the 17 group element form an oxide suppose ClO2,which has Cl+ ion which has two unpaired electron in the ground state.Therefore the group number is 17 group.
2)The name of the element is flevoirum which is called eka-lead.It is a post transition metal.
As it belongs to the carbon group thereofore the formula will be eka-PbO2 or FlO2
3)Ge belongs to group 14 and Se belongs to Gr-16 and electron affinity increases along the period because the electrons added to energy levels become closer to the nucleus, thus a stronger attraction between the nucleus and its electrons
5)F- <O2-<N^3- ,as these have the same electron so the radius will depend on the nuclear charge.More nuclear charge less will be the ionic size.Please rate my answer so that I can further help you in the future.Thanks
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