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← JEE Main 2022 · 26 Jun · Shift 2
ChemistryInteger+4 / -1Question 84 of 90

JEE Main 2022 · 26 Jun · Shift 2, Chemistry question 84

A fish swimming in water body when taken out from the water body is covered with a film of water of weight 36 g. When it is subjected to cooking at 100 °C, then the internal energy for vaporization in kJ mol−1^{-1} is ______. [nearest integer]

[Assume steam to be an ideal gas. Given ΔvapH⊖\Delta_{\rm vap}H^\ominus for water at 373 K and 1 bar is 41.1 kJ mol−1^{-1}; R=8.31R=8.31 J K−1^{-1}mol−1^{-1}]

Answer and worked solution

Official answer: 38

Per mole. ΔU=ΔH−ΔngRT=41.1−8.31×3731000≈41.1−3.1=38.0\Delta U=\Delta H-\Delta n_gRT=41.1-\dfrac{8.31\times373}{1000}\approx41.1-3.1=38.0 kJ mol−1^{-1} (the 36 g only fixes the amount, 2 mol).

Answer: 38