Q. Consider the following statements :
I. Ionisation energy is the energy required to remove an electron from an isolated gaseous atom from its ground state.
II. Ionisation energy can be either positive or negative.
III. The second ionisation enthalpy will be less than third but greater than first ionisation enthalpy.
Choose the incorrect statements

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Solution:

Statement II is incorrect.
It's correct form is as follows :
Energy is always required to remove electrons from an atom and hence ionisation enthalpies are always positive. Rest other statements are correct.