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Thermodynamics

29 Questions
GATE→2026→Thermodynamics→Thermodynamics
Q1
MCQ[1 Mark]
Consider a closed system of one mole of an ideal gas undergoing a polytropic process. The process follows PVn=constantPV^{n} = \text{constant}, where PP is the pressure, VV is the volume and nn is a constant. If the process is isobaric, which one of the following is the value of nn?
GATE→2026→Thermodynamics→Thermodynamics
Q2
MCQ[1 Mark]
According to the phase rule, which one of the following is the number of degrees of freedom for pure water at its triple point?
GATE→2026→Thermodynamics→Thermodynamics
Q3
MSQ[1 Mark]
Which of the following statements regarding the heat of reaction is/are CORRECT?
GATE→2026→Thermodynamics→Thermodynamics
Q4
MCQ[2 Marks]
K value is defined as the ratio of mole fraction of a component in the vapor phase to that in the liquid phase. The K values of propane and iso-butane at 293 K are given in the table. Pressure (kPa) | K values (Propane) | K values (iso-Butane) 1100 | 1.8 | 0.85 1200 | 1.6 | 0.75 1300 | 1.4 | 0.65 1400 | 1.25 | 0.5 1500 | 1.1 | 0.45 Which one of the following is closest to the bubble point pressure (in kPa) of an equimolar mixture of propane and iso-butane at 293 K?
GATE→2026→Thermodynamics→Thermodynamics
Q5
NAT[2 Marks]
Methanol is formed by the following gas phase homogeneous reaction: CO(g)+2H2(g)=CH3OH(g)\text{CO}(g) + 2\text{H}_2(g) = \text{CH}_3\text{OH}(g) The standard Gibbs free energies of formation at 298 K for CO\text{CO} and CH3OH\text{CH}_3\text{OH} are −137 kJ mol−1-137~\text{kJ mol}^{-1} and −162 kJ mol−1-162~\text{kJ mol}^{-1}, respectively. (Standard Gibbs free energy of formation of H2(g)\text{H}_2(g) is 0). The value of universal gas constant is 8.314 J mol−1K−18.314~\text{J mol}^{-1}\text{K}^{-1}. The equilibrium constant for the given reaction at 298 K is ______ ×104\times 10^4 (rounded off to one decimal place).
GATE→2026→Thermodynamics→Thermodynamics
Q6
NAT[2 Marks]
A gas mixture of 50 wt.% argon and 50 wt.% helium flowing through a horizontal tube of uniform diameter at a rate of 1 kg s−11~\text{kg s}^{-1} is heated from 300 K to 400 K at 1 bar. Neglect shaft work, and changes in kinetic as well as potential energies between the inlet and the outlet. Assume the mixture exhibits ideal gas behavior. The specific enthalpies of the components are given in the following table: Component | Specific enthalpy at 300 K (kJ kg−1^{-1}) | Specific enthalpy at 400 K (kJ kg−1^{-1}) Argon | 348 | 400 Helium | 1574 | 2092 At steady state, the heat input required (in kW) is ______ (rounded off to the nearest integer).
GATE→2025→Thermodynamics→Thermodynamics
Q7
MCQ[1 Mark]
The number of independent intensive variables that need to be specified to determine the thermodynamic state of a ternary mixture at vapor-liquid-liquid equilibrium is
GATE→2025→Thermodynamics→Thermodynamics
Q8
MCQ[1 Mark]
The boundary of a system does not allow exchange of either mass or energy (in the form of heat and/or work) with the surroundings. The system is termed
GATE→2025→Thermodynamics→Thermodynamics
Q9
NAT[1 Mark]
The following data is given for a ternary ABC gas mixture at 12 MPa and 308 K... The fugacity of the gas mixture is ______ MPa (rounded off to 3 decimal places).
GATE→2025→Thermodynamics→Thermodynamics
Q10
NAT[1 Mark]
Ideal nonreacting gases A and B are contained inside a perfectly insulated chamber... The change in total entropy for the process is ______ J/K (rounded off to 1 decimal place).
GATE→2025→Thermodynamics→Thermodynamics
Q11
NAT[2 Marks]
An ideal monoatomic gas is contained inside a cylinder-piston assembly connected to a Hookean spring... final equilibrium temperature of the gas is ______ K (rounded off to the nearest integer).
Figure for Question 11
GATE→2025→Thermodynamics→Thermodynamics
Q12
NAT[2 Marks]
An adiabatic pump of efficiency 40% is used to increase water pressure from 200 kPa to 600 kPa... maximum temperature rise of water across the pump is ______ °C (rounded off to 3 decimal places).
GATE→2025→Thermodynamics→Thermodynamics
Q13
NAT[2 Marks]
A and B form an azeotrope. The saturation vapour pressures of A and B are 87 kPa and 72.7 kPa... The azeotrope composition is ______ mol% A (rounded off to nearest integer).
GATE→2025→Thermodynamics→Thermodynamics
Q14
NAT[2 Marks]
Methanol is produced by the reversible, gas-phase hydrogenation of carbon monoxide... equilibrium constant is 1.68 at reaction conditions. Mole fraction of H2H_2 in product is 0.4. Mole fraction of methanol is ______ (rounded off to 2 decimal places).
GATE→2024→Thermodynamics→Thermodynamics
Q15
NAT[1 Mark]
Consider binary mixture. Given (∂V‾A/∂xA)=22(\partial \overline{V}_A / \partial x_A) = 22 and (∂V‾B/∂xA)=−18(\partial \overline{V}_B / \partial x_A) = -18, value of xAx_A is.
GATE→2024→Thermodynamics→Thermodynamics
Q16
NAT[2 Marks]
Methane combustion in insulated furnace... for r=1.05rsr = 1.05 r_s, exit flue gas temperature is °C.
GATE→2024→Thermodynamics→Thermodynamics
Q17
NAT[2 Marks]
Isolated system with compartments A and B separated by movable rigid wall with spring... final equilibrium temperature of gas in A is K.
Figure for Question 17
GATE→2024→Thermodynamics→Thermodynamics
Q18
NAT[2 Marks]
Ethylene obeys truncated virial EOS. At 340 K, slope of compressibility factor vs pressure is given. Value of (∂GR/∂P)T(\partial G^R / \partial P)_T in cm3mol−1\text{cm}^3 \text{mol}^{-1} is.
GATE→2024→Thermodynamics→Thermodynamics
Q19
NAT[2 Marks]
Heat available at 2 kW2 \text{ kW} from thermal reservoir at 400400 K. Two-stage process rejects heat at 360360 K and 300300 K. Power delivered at 50% Carnot efficiency is kW.
GATE→2023→Thermodynamics→Thermodynamics
Q20
MCQ[1 Mark]
For a reversible endothermic chemical reaction, which figure shows the CORRECT dependence of equilibrium constant KK on temperature TT?
Figure for Question 20
GATE→2023→Thermodynamics→Thermodynamics
Q21
MCQ[1 Mark]
John performed experiment under reversible conditions (Delta S_rev), Jane under irreversible conditions (Delta S_irr). Which relationship is CORRECT?
GATE→2023→Thermodynamics→Thermodynamics
Q22
MSQ[1 Mark]
Consider a system where a Carnot engine is operating between a source and a sink. Which statements are NOT correct?
GATE→2023→Thermodynamics→Thermodynamics
Q23
MCQ[2 Marks]
Enthalpy HH of binary liquid system given. Partial molar enthalpy of species 1 at infinite dilution H‾1∞\overline{H}_1^\infty (in J mol−1^{-1}) is
GATE→2022→Thermodynamics→Thermodynamics
Q24
MCQ[1 Mark]
For single component system at VLE, relation that is NOT CORRECT among Helmholtz free energy AA, volume VV, entropy SS, moles NN is
GATE→2022→Thermodynamics→Thermodynamics
Q25
NAT[1 Mark]
5 moles benzene, 8 moles toluene, 7 moles xylene mixed at 25∘C25^\circ\text{C} and 1 bar assuming ideal solution. Total entropy change is J K−1\text{J K}^{-1}.
GATE→2022→Thermodynamics→Thermodynamics
Q26
MCQ[2 Marks]
N moles of ideal gas undergoing isochoric then isobaric expansion process. Heat gained by gas is
Figure for Question 26
GATE→2022→Thermodynamics→Thermodynamics
Q27
NAT[2 Marks]
Substance at 4circC4^circ\text{C} with β=0\beta = 0, κT\kappa_T, and molar volume given. Quantity [v(∂S/∂v)T][v (\partial S / \partial v)_T] evaluated is J mol−1^{-1} K$^{-1}.
GATE→2022→Thermodynamics→Thermodynamics
Q28
NAT[2 Marks]
Molar excess Gibbs free energy expression given. Value of ∫01ln⁡(γA/γB)dxA\int_{0}^{1} \ln(\gamma_A / \gamma_B) dx_A at 300 K and 1 bar is.
GATE→2022→Thermodynamics→Thermodynamics
Q29
NAT[2 Marks]
Vapour pressure data given. Estimated latent heat of vaporization at 360 K is kJ/mol.