Entropy and second law, entropy changes in processes

37 questions on Entropy and second law, entropy changes in processes from the Thermodynamics and Thermochemistry chapter: 6 NEET level, 15 JEE Main, 16 JEE Advanced. Each one opens with its answer and solution.

• The entropy change for melting one mole of ice at 273 K (reversibly, Delta_fusH = 6010 J mol^-1) is closest to NEET level
• In which of the following processes does the entropy of the system decrease? NEET level
• For a spontaneous process in an isolated system, which condition holds? NEET level
• Two moles of an ideal gas expand isothermally from 5.0 L to 20 L. With R = 8.314 J mol^-1K^-1, the entropy change of the gas is JEE Main level
• Two moles of a monatomic ideal gas are heated at constant volume from 300 K to 600 K. With R = 8.314 J mol^-1K^-1, the entropy change in J K^-1 (two decimals) i... JEE Main level
• An exothermic reaction at constant pressure releases 92.2 kJ of heat to a large surroundings at 298 K (reversible heat exchange with the surroundings). The entr... JEE Main level
• One mole of an ideal gas is taken from state 1 to state 2. Which statements are correct? JEE Main level
• One mole of ideal gas A and three moles of ideal gas B, both at the same temperature and pressure, are mixed at constant T and P. With R = 8.314 J mol^-1K^-1, t... JEE Main level
• 150 g of liquid water (c_P = 4.18 J g^-1K^-1, assumed constant) is heated reversibly from 293 K to 353 K. The entropy change of the water in J K^-1 (one decimal... JEE Main level
• A liquid obeys Trouton's rule (Delta_vapS approx 88 J mol^-1K^-1) and boils normally at 350 K. Its enthalpy of vaporisation is about JEE Main level
• Which of the following statements is/are correct? JEE Main level
• 100 g of water at 353 K is mixed with 200 g of water at 293 K in an insulated container. Take c_P = 4.18 J g^-1K^-1 (constant) and ignore the container. The tot... JEE Advanced level
• One mole of an ideal gas at 300 K and 10 atm expands isothermally against a constant external pressure of 1 atm until its pressure is 1 atm, in contact with a l... JEE Advanced level
• One mole of ice at 273 K is melted (Delta_fusH = 6010 J mol^-1) and the water is then heated reversibly to 353 K (C_P,m = 75.3 J mol^-1K^-1, constant). Which st... JEE Advanced level
• One mole of a monatomic ideal gas at 300 K and 1 atm is compressed adiabatically by a constant external pressure of 4 atm until the gas pressure is 4 atm. With ... JEE Advanced level
• A reversible Carnot engine absorbs 1000 J from a reservoir at 500 K and rejects heat to a reservoir at 300 K. Which statements are correct? JEE Advanced level
• Two moles of a diatomic ideal gas (vibrations ignored, R = 8.314 J mol^-1K^-1) change from 300 K, 10.0 L to 450 K, 25.0 L. The entropy change in J K^-1 (two dec... JEE Advanced level
• For N2O4(g) <=> 2NO2(g), Delta H deg = +57.2 kJ and the standard molar entropies are S deg(N2O4) = 304.2 and S deg(NO2) = 240.0 J K^-1mol^-1. Assuming Delta H d... JEE Advanced level
• Two identical blocks of constant heat capacity C at 400 K and 200 K are brought to thermal equilibrium. Which statements are correct? JEE Advanced level
• In which of the following processes does the entropy of the system decrease? NEET level
• For a spontaneous process in an isolated system, which statement is correct? NEET level
• According to the third law of thermodynamics, the entropy of a perfectly crystalline pure substance at absolute zero is NEET level
• Two moles of an ideal gas expand reversibly and isothermally from 5.0 L to 20.0 L. With R=8.314 J mol^-1K^-1, Delta S_sys is closest to JEE Main level
• The enthalpy of fusion of benzene is 9.87 kJ mol^-1 and its melting point is 278.5 K. The entropy of fusion is closest to JEE Main level
• A reaction has Delta H=+42.6 kJ mol^-1 and Delta S=+120 J mol^-1K^-1, both assumed independent of temperature. The reaction is spontaneous JEE Main level
• Three moles of liquid water (C_P=75.3 J mol^-1K^-1, assumed constant) are heated reversibly at constant pressure from 300 K to 350 K. The entropy change of the ... JEE Main level
• At 298 K and constant pressure, N2(g) + 3H2(g) -> 2NH3(g) has Delta H=-92.2 kJ. Treating the surroundings as a large reservoir at 298 K, Delta S_surr is JEE Main level
• Select the correct statement(s) about entropy. JEE Main level
• A reaction has Delta H=-100 kJ mol^-1 and Delta S=-200 J mol^-1K^-1 (temperature independent). Select the correct statement(s). JEE Main level
• Two moles of a monatomic ideal gas (C_V=tfrac32R) change reversibly from 300 K and 10.0 L to 450 K and 40.0 L. Using R=8.314 J mol^-1K^-1, find Delta S of the g... JEE Advanced level
• A large reservoir at 600 K transfers 1200 J of heat directly to a large reservoir at 400 K through a conducting rod. The entropy change of the universe is JEE Advanced level
• Use the data below (at 298 K) for CaCO3(s) -> CaO(s) + CO2(g) and assume Delta H and Delta S are temperature independent. Delta_fH deg/kJ mol^-1: CaCO3=-1206.9,... JEE Advanced level
• 100 g of water at 80 degC is mixed adiabatically with 100 g of water at 20 degC (specific heat 4.18 J g^-1K^-1, constant). The entropy change of the universe is... JEE Advanced level
• Two moles of an ideal gas at 300 K expand freely (into vacuum, adiabatic walls) from 5.0 L to 15.0 L. The gas is then compressed reversibly and isothermally at ... JEE Advanced level
• One mole of an ideal gas at 300 K doubles its volume, once by (I) a reversible isothermal expansion and once by (II) a free expansion into vacuum. Use R=8.314 J... JEE Advanced level
• A reaction has Delta H=+66.0 kJ mol^-1 and Delta S=+110 J mol^-1K^-1, both temperature independent. Select the correct statement(s). JEE Advanced level
• One mole of water vaporises reversibly at 373 K and 1 atm; Delta_vapH=40.7 kJ mol^-1 and R=8.314 J mol^-1K^-1 (steam ideal, liquid volume neglected). Select the... JEE Advanced level