Which of the following represents the correct order of incr…

Chemistry Classification of Elements and Periodicity NTA Abhiyas Question Single Correct MCQ

Published by: CGP EDU Academic Team

Published on: August 13, 2026

Which of the following represents the correct order of increasing first ionization enthalpy for Ca, Ba, S, Se and Ar ?

Ba < Ca < Se < S < Ar

Ca < Ba < S < Se < Ar

Ca < S < Ba < Se < Ar

S < Se < Ca < Ba < Ar

Text Solution

Verified by Experts

The correct answer is:

Ba < Ca < Se < S < Ar

Ba, Ca belong to gr IIA ( alkaline earth metals)

Se and S belong to gr VIA (Chalcogens)

and as we go down the group ionization enthalpy decreases with increasing atomic size. So, Ba < Ca and Se<S

Ar has stable completely filled electronic configuration and, there fore,has highest ionization enthalpy. Hence, the correct order is

Ba < Ca < Se < S < Ar

in kJmol -1 503 590 941 999 1520

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