Q 1 :

Ice at –5°C is heated to become vapor with temperature of 110°C at atmosphere pressure. The entropy change associated with this process can be obtained from    [2025]

• ${\int }_{268K}^{273K}{C}_{p,m} dT+\frac{\Delta H_{m,\text{fusion}}}{T_f}+\frac{\Delta H_{m,\text{vaporisation}}}{T_b}+{\int }_{273K}^{373K}{C}_{p,m} dT+{\int }_{373K}^{383K}{C}_{p,m} dT$

   

• ${\int }_{268K}^{383K}{C}_p dT+\frac{\Delta H_{\text{melting}}}{273}+\frac{\Delta H_{\text{boiling}}}{373}$

   

• ${\int }_{268K}^{273K}\frac{C_{p,m}}{T} dT+\frac{\Delta H_{m,\text{fusion}}}{T_f}+\frac{\Delta H_{m,\text{vaporisation}}}{T_b}+{\int }_{273K}^{373K}\frac{C_{p,m}dT}{T} +{\int }_{373K}^{383K}\frac{C_{p,m}dT}{T}$

   

• ${\int }_{268K}^{383K}{C}_p dT+\frac{q_{\text{rev}}}{T}$

   

Q 2 :

One mole of an ideal gas at 350 K is in a 2.0 L vessel of thermally conducting walls, which are in contact with the surroundings. It undergoes isothermal reversible expansion from 2.0 L to 3.0 L against a constant pressure of 4 atm. The change in entropy of the surroundings $\left(\mathrm{\Delta S}\right)$ is ______ ${\mathrm{JK}}^{-1}$ (Nearest integer) Given: R = 8.314 J ${\mathrm{K}}^{-1}$ ${\mathrm{mol}}^{-1}$      [2023]

Q 3 :

30.4 kJ of heat is required to melt one mole of sodium chloride and the entropy change at the melting point is 28.4 J ${\mathrm{K}}^{-1}$ ${\mathrm{mol}}^{-1}$ at 1 atm. The melting point of sodium chloride is ________ K. (Nearest integer)            [2023]