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In second period of the modern periodic table, two elements X and Y have higher first ionization enthalpy values than the preceding and succeeding elements. X and Y are respectively
In second period of the modern periodic table, two elements X and Y have higher first ionization enthalpy values than the preceding and succeeding elements. X and Y are respectively
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The two main exceptions to the increasing trend of first ionization enthalpy across a period occur when removing an electron from a fully-filled s-orbital (Group 2, e.g., Be) and a half-filled p-orbital (Group 15, e.g., N). These configurations are extra stable, requiring more energy for ionization.
Updated On: Mar 30, 2026
- B, C
- Al, S
- Be, N
- Na, S
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The Correct Option is C
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