Arrange the elements Se, Cl and S in the increasing order of ionisation energy.

Ionisation energy is the energy required to remove one electron from a neutral atom of an element. S and Se belong to VIA group elements. Down the group ionisation energy decreases so S is having more IE value than Se. S and Cl are the elements of the same period the IE value increases from left to right. So, Cl is having more IE value than S. So the correct order of IP is Se<S<Cl