Which of the following shows the least value for standard enthalpy of atomization?

Zn

The correct answer is Option (2) → Zn

The standard enthalpy of atomization (ΔₐₜH°) is the energy required to convert one mole of metal atoms in solid state to gaseous atoms (M(s) → M(g)).

Among the 3d-series transition metals:

• Zn has completely filled 3d¹⁰ 4s² electronic configuration.
• It has no unpaired electrons → very weak metallic bonding (almost no d-d overlap).
• As a result, zinc has the weakest metallic bond in the 3d series.

Trend in 3d series:

V > Cr > Mn > Fe > Co > Ni > Cu > Zn (lowest)

Cu has high value due to strong metallic bonding + contribution from d-electrons, but Zn shows the lowest atomization enthalpy.