The five successive ionisation energies of an element are 800, 2427 ,3658, 25024 and 32824 kJ mol-1 respectively.The number of valence electron is

There is a large jump from IE3 (3658 kJ mol-1) to IE4 (25024 kJ mol-1). Therefore, it is very difficult to remove the 3rd valence electron.Hence, the answer is (1).