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KCET · Chemistry · Classification of Elements and Periodicity in Properties

The correct order of first ionisation enthalpy of given elements is

  1. A \(\mathrm{Li}<\mathrm{B}<\mathrm{Be}<\mathrm{C}\)
  2. B \(\mathrm{Be}<\mathrm{Li}<\mathrm{B}<\mathrm{C}\)
  3. C \(\mathrm{C}<\mathrm{B}<\mathrm{Be}<\mathrm{Li}\)
  4. D \(\mathrm{Li}<\mathrm{Be}<\mathrm{B}<\mathrm{C}\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(\mathrm{Li}<\mathrm{B}<\mathrm{Be}<\mathrm{C}\)

Step-by-step Solution

Detailed explanation

Ionisation enthalpy of elements generally
increases on going from left to right along a period.
But Be nane half-filled electronic configuration which requires more energy to ionise as compare to \(B\). Thus, the correct order will be \(\mathrm{Li}<\mathrm{B}<\mathrm{Be}<\mathrm{C}\).