Which is the correct order of ionization energies? — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Step 1: Write down the electronic configurations of Zinc (Zn: [Ar] 3d10 4s2) and Cadmium (Cd: [Kr] 4d10 5s2). Step 2: In both metals, the d-subshell is completely filled ((n-1)d10) both in their elemental state and common oxidation state (+2). Step 3: Because the d-electrons are highly stable and not available for bonding, they only lose their outer s-electrons, exhibiting a fixed valency of 2, corresponding to option (b).