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Why is the enthalpy of atomisation of Zn (126 kJ/mol) the lowest in the 3d series?
AZn is liquid at room temperature
BZn has no unpaired d-electron (3d¹⁰ 4s²) — interatomic metallic bonding uses ns electrons only; very weak
CZn does not form any compounds
DZn has a small atomic radius
Answer & Solution
Correct answer: B. Zn has no unpaired d-electron (3d¹⁰ 4s²) — interatomic metallic bonding uses ns electrons only; very weak
Zn ground state = **3d¹⁰ 4s² — no unpaired d-electron**, hence no d-contribution to metallic bonding. Only 4s electrons participate → weak metallic bond → very low ΔaH (~126 kJ/mol). Same low-bonding logic explains Cd, Hg.
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