Given below are two sets of elements from two different periods. Name the element with the highest ionisation potential in each of the following sets.

(a) Cl

(b) Ne

Reason

(a) Cl — Among the three elements, Cl is the rightmost in period 3. As ionisation energy increases when moving across a period from left to right hence ionisation energy is highest for Cl.

(b) Ne — It is the rightmost element in period 2 and an inert gas. Hence it has the highest ionisation potential.