JEE Thermodynamics PYQs with Solutions PDF, Download Now

A diatomic gas ( y= 1.4) does 100 J of work when it is expanded isobarically. Then the heat given to the gas ____ J.

10 mole of oxygen is heated at constant volume from $$30^{\circ}C  \text{to}  40^{\circ}C$$. The change in the internal energy of the gas is ____ cal (the molecular specific heat of oxygen at constant pressure, $$C_{p}= 7 \text{cal}/\text{mol}.^{\circ}C \text{and} R = 2 \text{cal}./\text{mol}.^{\circ}C).$$

The volume of an ideal gas increases 8 times and temperature becomes $$(1/4)^{th}$$ of initial temperature during a reversible change. If there is no exchange of heat in this process $$(\triangle Q = 0)$$ then identify the gas from the following options (Assuming the gases given in the options are ideal gases):

10 mole of an ideal gas is undergoing the process showu in the figure. The heat involved in the process from $$P_{1}$$ to $$P_{2}$$ is $$\alpha$$ Joule(P_{1}= 21.7Pa and $$P_{2} = 30$$ Pa, $$C_{v}=21J/K.mol, R=8.3 J/mol.K.$$) The value od $$\alpha$$ is _________.

One mole of an ideal diatomic gas expands from volume $$V$$ to $$2 V$$ isothermally at a temperature $$27^{o}C$$ and does W joule of work. lf the gas undergoes same magnitude of expansion adiabatically from $$27^{o}C$$ doing the same amount of work $$W$$, then its final temperature will be (close to) ____ $$^{\circ}C.$$
$$(\log_{e}2 = 0.693)$$

A thermodynamic system is taken through the cyclic process $$ABC$$ as shown in the figure. The total work done by the system during the cycle $$ABC$$ is ______ J.

Given are statements for certain thermodynamic variables, (A) Internal energy, volume (V) and mass (M) are extensive variables. (B) Pressure (P), temperature (T) and density $$(\rho)$$ are intensive variables. (C) Volume (V), temperature (T) and density $$(\rho)$$ are intensive variables. (D) Mass (M), temperature (T) and internal energy are extensive variables. Choose the correct answer from the options given below :

Water of mass m gram is slowly heated to increase the temperature from $$T_{1}$$ to $$T_{2}$$ The change in entropy of the water, given specific heat of water is $$1Jkg^{-1}K^{-1}$$, is :

Using the given P - V diagram, the work done by an ideal gas along the path ABCD is :

An ideal gas goes from an initial state to final state. During the process, the pressure of gas increases linearly with temperature. A. The work done by gas during the process is zero. B. The heat added to gas is different from change in its internal energy. C. The volume of the gas is increased. D. The internal energy of the gas is increased. E. The process is isochoric (constant volume process) Choose the correct answer from the options given below:

The magnitude of heat exchanged by a system for the given cyclic process ABCA (as shown in figure) is (in SI unit) :

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : In an insulated container, a gas is adiabatically shrunk to half of its initial volume. The temperature of the gas decreases. Reason (R): Free expansion of an ideal gas is an irreversible and an adiabatic process. In the light of the above statements, choose the correct answer from the options given below :

A Carnot engine (E) is working between two temperatures 473 K and 273 K . In a new system two engines - engine $$E_{1}$$ works between 473 K to 373 K and engine $$E_{2}$$ works between 373 K to 273 K . If $$\eta_{12},\eta_{1}$$ and $$\eta_{2}$$ are the efficiencies of the engines $$E,E_{1}$$ and $$E_{2}$$, respectively, then

The workdone in an adiabatic change in an ideal gas depends upon only :

An ideal gas initially at $$0^{\circ}$$C temperature, is compressed suddenly to one fourth of its volume. If the ratio of specific heat at constant pressure to that at constant volume is 3/2, the change in temperature due to the thermodynamic process is _____ K.

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : With the increase in the pressure of an ideal gas, the volume falls off more rapidly in an isothermal process in comparison to the adiabatic process.
Reason (R) : In isothermal process, PV = constant, while in adiabatic process $$PV^{\gamma}$$ = constant. Here $$\gamma$$ is the ratio of specific heats, P is the pressure and V is the volume of the ideal gas. In the light of the above statements, choose the correct answer from the options given below :

The difference of temperature in a material can convert heat energy into electrical energy. To harvest the heat energy, the material should have

A cup of coffee cools from $$90^{\circ}$$ to $$80^{\circ}$$ in t minutes when the room temperature is $$20^{\circ}$$. The time taken by the similar cup of coffee to cool from $$80^{\circ}$$ to $$60^{\circ}$$ at the same room temperature is :

A poly-atomic molecule ($$C_V = 3R,\, C_P = 4R$$, where R is gas constant) goes from phase space point $$A\ (P_A = 10^5\,\text{Pa},\ V_A = 4 \times 10^{-6}\,\text{m}$$ to point $$B\ (P_B = 5 \times 10^4\,\text{Pa},\ V_B = 6 \times 10^{-6}\,\text{m}^3)$$ to point $$C\,(P_C = 10^4\,\text{Pa},\; V_C = 8 \times 10^{-6}\,\text{m}^3).$$ A to B is an adiabatic path B and C to is an isothermal path. The net heat absorbed per unit mole by the system is :

P-T diagram of an ideal gas having three different densities $$\rho_1, \rho_2, \rho_3$$ (in three different cases) is shown in the figure. Which of the following is correct:

The pressure and volume of an ideal gas are related as $$PV^{3/2} = K$$ (Constant). The work done when the gas is taken from state $$A(P_1, V_1, T_1)$$ to state $$B(P_2, V_2, T_2)$$ is :

A diatomic gas $$(\gamma = 1.4)$$ does 200 J of work when it is expanded isobarically. The heat given to the gas in the process is:

$$0.08$$ kg air is heated at constant volume through $$5°C$$. The specific heat of air at constant volume is $$0.17 \text{ kcal kg}^{-1} \text{ °C}^{-1}$$ and $$1 \text{ J} = 4.18 \text{ joule cal}^{-1}$$. The change in its internal energy is approximately.

During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its absolute temperature. The ratio of $$\frac{C_p}{C_v}$$ for the gas is :

A thermodynamic system is taken from an original state $$A$$ to an intermediate state $$B$$ by a linear process as shown in the figure. Its volume is then reduced to the original value from $$B$$ to $$C$$ by an isobaric process. The total work done by the gas from $$A$$ to $$B$$ and $$B$$ to $$C$$ would be :

Two thermodynamical processes are shown in the figure. The molar heat capacity for process $$A$$ and $$B$$ are $$C_A$$ and $$C_B$$. The molar heat capacity at constant pressure and constant volume are represented by $$C_P$$ and $$C_V$$, respectively. Choose the correct statement.

Choose the correct statement for processes $$A$$ & $$B$$ shown in figure.

The given figure represents two isobaric processes for the same mass of an ideal gas, then

A sample of gas at temperature $$T$$ is adiabatically expanded to double its volume. Adiabatic constant for the gas is $$\gamma = 3/2$$. The work done by the gas in the process is: ($$\mu = 1$$ mole)

Match List-I with List-II :

Choose the correct answer from the options given below :

During an adiabatic process, if the pressure of a gas is found to be proportional to the cube of its absolute temperature, then the ratio of $$\frac{C_P}{C_V}$$ for the gas is :

The heat absorbed by a system in going through the given cyclic process is :

To project a body of mass $$m$$ from earth's surface to infinity, the required kinetic energy is (assume, the radius of earth is $$R_E$$, $$g =$$ acceleration due to gravity on the surface of earth):

The specific heat at constant pressure of a real gas obeying $$PV^2 = RT$$ equation is:

A total of $$48 \text{ J}$$ heat is given to one mole of helium kept in a cylinder. The temperature of helium increases by $$2°C$$. The work done by the gas is: Given, $$R = 8.3 \text{ J K}^{-1} \text{ mol}^{-1}$$.

Energy of 10 non rigid diatomic molecules at temperature $$T$$ is :

Two different adiabatic paths for the same gas intersect two isothermal curves as shown in P-V diagram. The relation between the ratio $$\frac{V_a}{V_d}$$ and the ratio $$\frac{V_b}{V_c}$$ is:

The volume of an ideal gas $$(\gamma = 1.5)$$ is changed adiabatically from 5 litres to 4 litres. The ratio of initial pressure to final pressure is:

A real gas within a closed chamber at $$27°C$$ undergoes the cyclic process as shown in figure. The gas obeys $$PV^3 = RT$$ equation for the path $$A$$ to $$B$$. The net work done in the complete cycle is (assuming $$R = 8 \text{ J/molK}$$):