For aluminium, electronic configuration is 1s2,2s22p63s23p1 Al⟶Al++e−→IE1 Al+⟶Al2++e−→IE2 Al2+⟶Al3++e−→IE3 If aluminium loses 3e−, it attains stable electronic configuration of neon which is 1s2,2s2,2p6. So, aluminium can lose 3e−easily to get stabilise. and next IE will be higher. According to question, the IE values are 5.98,18.8,28.4,120.1... First three IE values are small so, the element is aluminium.