Statement 1 : SO2,  NO3−  and CO32− are isoelectronic as well as isostructural species.Statement 2 : The d and f-orbitals do not shield the nuclear charge very effectively. Therefore, there is significant reduction in the size of the ions, just after d or f orbitals have been completely filled.

S1 : SO2,  NO3−  and CO32− have same number of electrons (i.e. 32) but have different molecular geometry.  S2 :  The d- and f-orbitals do not shield the nuclear charge very effectively. Therefore, there is significant reduction in the size of the ions, just after d or f-orbitals have been completely filled. This is called lanthanide contraction.