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NEET 2023
Exam
NEET
Year
2023
Subject
Chemistry
Chapter
d and f Block Elements

NEET 2023 · Chemistry · d and f Block Elements

Given below are two statements : one is labelled as Assertion (A)...

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Ionisation enthalpies of early actinoids are lower than for early lanthanoids. Reason (R) : Electrons are entering 5f5 f orbitals in actinoids which experience greater shielding from nuclear charge. In the light of the above statements, choose the correct answer from the options given below:

Options

  1. ABoth (A)(\mathbf{A}) and (R)(\mathbf{R}) are true and (R)(\mathbf{R}) is the correct explanation of (A)(\mathbf{A}).
  2. BBoth (A)(\mathbf{A}) and (R)(\mathbf{R}) are true but (R)(\mathbf{R}) is not the correct explanation of (A)(\mathbf{A}).
  3. C(A) is true but (R) is false.
  4. D(A) is false but (R)(\mathbf{R}) is true.

Correct answer

A. Both (A)(\mathbf{A}) and (R)(\mathbf{R}) are true and (R)(\mathbf{R}) is the correct explanation of (A)(\mathbf{A}).

Step-by-step solution

Ionisation enthalpies of early actinoids are lower than early lanthanoids. This is because 5f5 f orbitals will penetrate less into the inner core of electrons. The 5f5 f electrons, will be more effectively shielded from the nuclear charge than the 4f4 f electrons of corresponding lanthanoids.
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