Question
Which of the following represents the correct order of increasing first ionisation enthalpy for Ca, Ba, S, Se and Ar?
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Ca <S<Ba<Se<Ar
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S< Se<Ca<Ba< Ar
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Ba< Ca<Se< S< Ar
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Ca<Ba<S<Se<Ar
Solution
C.
Ba< Ca<Se< S< Ar
Ionisation energy increases along period from left to right and decreases down a group. The position of given elements in the periodic table is as;
Increasing order of first ionization enthalpy is Ba < Ca < Se < S < Ar
