Question

Which of the following is not correct with the property mentioned against them?

• A. I$^-$>I>I$^+$ : radius
• B. Li>Be>B : first ionization enthalpy
• C. Cl>S>P : electronegativity
• D. Rb>K>Na : screening effect

Hint:

Ionization energy increases across a period; exceptions are due to stable configurations.

Answer 1

The Correct Option is B

Ionization enthalpy increases across a period. The correct trend is: Li<B<Be
Although Be has a filled s-subshell (stable), its ionization enthalpy is higher than B.
Hence, the statement “Li>Be>B” is incorrect. The correct order is: Li<B<Be.