The successive ionisation energies of a certain element areI1=577.9 KJ.mol-1 I2=1820 KJ.mol-1 I3=2750 KJ.mol-1 I4=11600 KJ.mol-1 I5=14800 KJ.mol-1 The element for which this pattern of ionization energies suits is

From the given data there is a sudden jump in ionization  observed for the removal of FOURTH electron, therefore the valency of the element should be THREE.Hence the element is  Aluminium which attains inert gas configuration by losing three electrons.