The melting point of copper is higher than that of zinc because

The correct answer is Option (4) → The ‘s’ as well as ‘d’ electrons of copper are involved in metallic bonding

The melting point of a metal rises with the strength of its metallic bonding, and this grows with the number of electrons each atom gives to the bonding.

• Copper (Z = 29): [Ar]3d¹⁰4s¹. Its 3d electrons are close in energy to the 4s electron and can be used; copper even loses a 3d electron to form \( \ce{Cu^2+} \) (3d⁹). So both 4s and 3d electrons take part in metallic bonding.

• Zinc (Z = 30): [Ar]3d¹⁰4s². The 3d subshell is completely filled in the atom and in \( \ce{Zn^2+} \) (3d¹⁰), so only the 4s electrons bond.

Weaker metallic bonding gives zinc the lower melting point.

Why the other options are incorrect

Option (1) Copper has a bcc structure — Incorrect. Copper has a ccp (cubic close packed) lattice, not bcc.

Option (2) The atomic volume of copper is higher — Incorrect. The copper atom is smaller (metallic radius 128 pm against 137 pm for zinc), so its atomic volume is lower, not higher.

Option (3) Zinc has unpaired d electrons, while copper has none — Incorrect. Zinc is 3d¹⁰, so all its d electrons are paired; it has no unpaired d electrons.

NCERT (2026-27 edition):
4.3.1 Physical Properties – “The transition metals (with the exception of Zn, Cd and Hg) are very hard and have low volatility. Their melting and boiling points are high. … The high melting points of these metals are attributed to the involvement of greater number of electrons from (n-1)d in addition to the ns electrons in the interatomic metallic bonding.”

4.2 Electronic Configurations of the d-Block Elements – “The electronic configurations of outer orbitals of Zn, Cd, Hg and Cn are represented by the general formula (n-1)d¹⁰ns². The orbitals in these elements are completely filled in the ground state as well as in their common oxidation states.”