Assertion : Ionisation enthalpies of the earl | vedclass

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(C) The Assertion is True: The ionisation enthalpies of early actinoids are lower than those of early lanthanoids because the $5f$ orbitals are more e

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Assertion is True but the Reason is False.

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(C) The Assertion is True: The ionisation enthalpies of early actinoids are lower than those of early lanthanoids because the $5f$ orbitals are more extended in space than $4f$ orbitals,making the $5f$ electrons less tightly bound to the nucleus.The Reason is False: The shielding effect of $5f$ electrons is actually poorer than that of $4f$ electrons. Because $5f$ electrons are less effective at shielding,the effective nuclear charge experienced by the outer electrons is higher,but the spatial extension of $5f$ orbitals dominates,leading to lower ionisation enthalpies for actinoids compared to lanthanoids.

Assertion : Ionisation enthalpies of the early actinoids are lower than for early lanthanoids.
Reason : $5f$ electrons are more effectively shielded from nuclear charge than $4f$ electrons.

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Assertion : Ionisation enthalpies of the early actinoids are lower than for early lanthanoids.Reason : $5f$ electrons are more effectively shielded from nuclear charge than $4f$ electrons.