1
JEE Main 2020 (Online) 2nd September Evening Slot
Numerical
+4
-0
The heat of combustion of ethanol into carbon dioxide and water is – 327 kcal at constant pressure. The heat evolved (in cal) at constant volume and 27oC (if all gases behave ideally) is (R = 2 cal mol–1 K–1) ________.
2
JEE Main 2020 (Online) 2nd September Morning Slot
Numerical
+4
-0
The internal energy change (in J) When 90 g of water undergoes complete evaporation at 100oC is ______.

(Given : $$\Delta$$Hvap for water at 373 K = 41 kJ/mol,
R = 8.314 JK–1 mol–1)
3
JEE Main 2020 (Online) 9th January Evening Slot
Numerical
+4
-0
A cylinder containing an ideal gas (0.1 mol of 1.0 dm3) is in thermal equilibrium with a large volume of 0.5 molal aqueous solution of ethylene glycol at its freezing point. If the stoppers S1 and S2 (as shown in the figure) are suddenly withdrawn, the volume of the gas in litres after equilibrium is achieved will be____.

(Given, Kf (water) = 2.0 K kg mol–1,
R = 0.08 dm3 atm K–1 mol–1)

4
JEE Main 2020 (Online) 9th January Evening Slot
Numerical
+4
-0
A sample of milk splits after 60 min. at 300 K and after 40 min. at 400 K when the population of lactobacillus acidophilus in it doubles. The activa tion energy (in kJ/ mol) for this process is closest to__________.

(Given, R = 8.3 J mol–1 K–1, $$\ln \left( {{3 \over 2}} \right) = 0.4$$, e–3 = 4.0)
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