Subshell Electronic Configuration

The key to solving this problem is to determine the number of unpaired electrons for the given ions. Below is the detailed explanation and matching of List-I with List-II:

1. Zn : Zinc's atomic number is 30, with an electron configuration of [Ar] 3d¹⁰ 4s². Zn loses two electrons, resulting in a configuration of [Ar] 3d¹⁰. Since all electrons in 3d are paired, 0 unpaired electrons. Match: (I).
2. Cu : Copper has an atomic number of 29 with a configuration of [Ar] 3d¹⁰ 4s¹. In Cu , it loses two electrons, resulting in [Ar] 3d⁹. There is one unpaired electron in the 3d orbital. Match: (III).
3. Ni : Nickel has an atomic number of 28, with a configuration of [Ar] 3d⁸ 4s². In Ni , it loses two electrons, leading to [Ar] 3d⁸. It has two unpaired electrons. Match: (IV).
4. Fe : Iron has an atomic number of 26 with a configuration of [Ar] 3d⁶ 4s². Fe loses two electrons, resulting in [Ar] 3d⁶, with four unpaired electrons. Match: (II).

Based on the above analysis, the correct matches are: (A)-(I), (B)-(III), (C)-(IV), (D)-(II).