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

$Ca\lt S \lt Ba \lt Se \lt Ar$

$S\lt Se \lt Ba \lt Ca \lt Ar$

$Ba\lt Ca \lt Se \lt S \lt Ar$

$Ca\lt Se \lt Ba \lt S \lt Ar$

Option C

Ionisation energy increases along a period from left to right and decreases down a group. The position of given elements in the periodic table is as

2 16 18

Ca S Ar

Ba Se

Thus, the order of increasing $\triangle H_{IE_{1}}$ is

Ba <Ca< Se < S< Ar

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