Metals generally melt at very high temperatures. Among the following which one has the highest melting point?

🧠 Transition metals form strong metallic lattices — Ag's many delocalized electrons hold it together up to nearly 1000 °C Metallic bond strength depends on the number of delocalized valence electrons and how tightly the lattice packs them. Transition metals with d-electron involvement (like Ag) make very strong metallic lattices — high MP. The other three options are notorious low-MP outliers.

🗺️ Compare melting points Ga: $\approx 30\,°\text{C}$ — melts in your hand. Hg: $\approx -39\,°\text{C}$ — liquid at room temperature. Cs: $\approx 28.5\,°\text{C}$ — alkali metal with weak metallic bonding. Ag: $\approx 962\,°\text{C}$ — typical strong-bonded transition metal.

Ag is the only one above $100\,°\text{C}$. Easily the highest MP.

⚠️ The trap Students sometimes pick Hg "because it is heavy and dense, must be high MP". Mass and density don't decide MP — bond strength does. Hg's almost-filled $5d^{10}\,6s^2$ shell makes its outer electrons hesitate to delocalize, so the metallic bond is weak. Mass matters for density, not for metallic bond strength.

$\boxed{\text{Answer: (b)}}$