Q 11-10-061JEE MainJEE Main 2024 (30 Jan, Shift 2)Medium
A block of ice at $-10^\circ\text{C}$ is slowly heated and converted to steam at $100^\circ\text{C}$. Which of the following curves represents the phenomenon qualitatively?
Answer: (D) see figure
Starting at $-10^\circ\text{C}$ the temperature of ice rises, then stays constant at $0^\circ\text{C}$ while it melts, rises again as water is heated to $100^\circ\text{C}$, and finally stays constant at $100^\circ\text{C}$ while water turns to steam. The boiling plateau is much longer than the melting one because the latent heat of vaporisation ($\approx 540\ \text{cal g}^{-1}$) is far larger than that of fusion ($80\ \text{cal g}^{-1}$).
Only graph (4) shows rise → plateau → rise → longer final plateau.
Solution by Sreeraj P, M.Sc Physics