Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Cu ⁺ and Sc ³⁺ both exhibit a spin-only magnetic moment of zero. Reason (R): Both ions lack unpaired electrons due to a completely filled 3d subshell. In the light of the above statements, choose the most appropriate answer from the options given below.

Step-by-step solution

Assertion (A): The electronic configuration of Cu is [ Ar ] 3d¹⁰ 4s^1 . Thus, Cu ⁺ is [ Ar ] 3d¹⁰ . It has 0 unpaired electrons, so its magnetic moment is zero. The electronic configuration of Sc is [ Ar ] 3d^1 4s^2 . Thus, Sc ³⁺ is [ Ar ] 3d^0 . It also has 0 unpaired electrons, so its magnetic moment is zero. Therefore, the Assertion is true. Reason (R): While Cu ⁺ lacks unpaired electrons because of a completely filled 3d subshell ( 3d¹⁰ ), Sc ³⁺ lacks unpaired electrons because it has an empty 3d subshell ( 3d^