Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): The first ionization enthalpy of 3d series elements is more than that of group 2 metals
Reason (R): In 3d series of elements successive filling of d-orbitals takes place.
In the light of the above statements, choose the correct answer from the options given below:

Assertion (A): The first ionization enthalpy of 3d series elements is more than that of Group 2 metals.

Reason (R): In 3d series, successive filling of d-orbitals takes place.

Analysis of Assertion (A):

The first ionization enthalpies (in kJ/mol) of the 3d series elements range from approximately 631 (Sc) to 906 (Zn). When compared with the Group 2 element of the same period (Ca, IE₁ = 590 kJ/mol), all 3d elements have higher ionization enthalpies. This is because the nuclear charge increases across the period while d-electrons provide poor shielding.

Assertion (A) is True.

Analysis of Reason (R):

In the 3d series (Sc to Zn), d-orbitals are progressively filled from $$3d^1$$ to $$3d^{10}$$.

Reason (R) is True.

Connection: The successive filling of d-orbitals results in poor shielding of nuclear charge, leading to higher effective nuclear charge and thus higher ionization enthalpy compared to the preceding Group 2 element. R correctly explains A.

The correct answer is Option A: Both (A) and (R) are true and (R) is the correct explanation of (A).