JEE Main 2022 · 24 June · evening · Single correct · +4 / −1
Metals generally melt at very high temperature. Amongst the following, the metal with the highest melting point will be :
- (a) Hg
- (b) Ag
- (c) Ga
- (d) Cs
Answer and solution
Answer (b) Ag
Solution
Chemistry ma’am · 2 steps
Three of these melt in your hand or are already liquid. Only silver needs a real furnace.
- What sets melting point. A metal melts when heat overcomes its metallic bonding. More electrons in the sea and smaller atoms give stronger bonding and a higher melting point.
Metal Melting point Why Hg -39 °C, liquid at room temperature Filled 5d¹⁰6s² shell holds its 6s electrons tightly, so they barely join the electron sea Ag 962 ° C Transition metal, close-packed lattice, strong metallic bonding Ga 30 °C Unusual structure built from Ga₂ pairs, which breaks up easily Cs 28 °C Only one valence electron spread over a very large atom, so metallic bonding is weak - So. Silver melts near 962 °C, far above the other three, so the answer is (b) Ag.
The idea to keep. Remember the low-melting oddballs: Hg is liquid, while Ga and Cs melt just above room temperature. A transition metal like Ag beats all of them.
Answer from the NTA final answer key. Solution by PrepWiser.