Question

First five ionization energy of element X are
578,1817,2745,11578,14831
X found in which group of periodic table and why?

Answer 1

to find out the group number of the element, you need to know the number of outer ( valence electrons ) in the element.

we see, from the ionisation energy(I.E.) data, that the I.E. value increases till the third electron's removal and then increases abruptly.

this abrupt increase is attributed to the energy required for the removal of an electron from the stable noble gas configuration.
this means, after removing three electrons, we get a noble gas configuration.

THIS MEANS THE VALENCE ELECTRONS IN THE ELEMENT ARE 3
THIS MEANS THE ELEMENT BELONGS TO THIRD GROUP.

i hope this is clear to you/