Thermodynamics PYQs Set 12 (PDF)

Set 12 of 17 · Questions 331-360 of 484

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Mere Teacher · Previous Year Questions JEE Main Physics · Thermodynamics · Set 12 (Q331-360)
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331. $A monoatomic gas does 100 J of work when it is expanded isobarically. How much of heat is given to the gas in the process.$ (1) $150 J$ (2) $200 J$ (3) $250 J$ (4) $300 J$ 332. $A diatomic gas has an initial internal energy of 80 cal. A work of 18 cal is done on the gas and the gas releases heat energy of 42 J . The final internal energy of the gas is$ (1) $20 J$ (2) $369.6 J$ (3) $54 J$ (4) $20 cal$ 333. $To raise the temperature of a certain mass of gas by 50^{\circ} C at a constant pressure, 160 calories of heat is required. When the same mass of gas is cooled by 100^{\circ} C at constant volume, 240 calories of heat is released. How many degrees of freedom does each molecule of this gas have (assume gas to be ideal)?$ (1) $6$ (2) $7$ (3) $3$ (4) $5$ 334. $An ideal gas, undergoing adiabatic change, has which of the following pressure temperature relationship?$ (1) $P^{γ} T^{1 - γ} = constant$ (2) $P^{1 - γ} T^{γ} = constant$ (3) $P^{γ - 1} T^{γ} = constant$ (4) $P^{γ} I^{γ - 1} = constant.$ 335. $A heat engine has an efficiency η . Temperatures of source and sink are each decreased by 100 K. The efficiency of the engine$ (1) $Increases$ (2) $Decreases$ (3) $Remains constant$ (4) $Becomes 1$ 336. $The temperature of sink of Carnot engine is 2 7^{0} C and its efficiency is 25%. The temperature of source is$ (1) $22 7^{0} C$ (2) $12 7^{0} C$ (3) $2 7^{0} C$ (4) $32 7^{0} C$ 337. $Consider a Carnot cycle operating between source temperature 750 K and sink temperature 350 K producing 1.25 kJ of mechanical work per cycle, the heat transferred to the engine by the reservoirs$ (1) $1.34 kJ$ (2) $2.34 kJ$ (3) $3.34 kJ$ (4) $4.34 kJ$ 338. $The Carnot heat engine have an efficiency of 50 % . The temperature of sink is maintained at 500 K . To increase the efficiency upto 80 %, the increment in the source temperature is$ (1) $1500 K$ (2) $2500 K$ (3) $500 K$ (4) $2000 K$ 339. $At 1 0^{o} C the value ofthe density of a fixed mass of an ideal gas divided by its pressure is x . At 11 0^{o} C this ratio is$ (1) $\frac{10}{110} x$ (2) $\frac{283}{383} x$ (3) $x$ (4) $\frac{383}{283} x$ 340. $The (WlQ) of a Carnot engine is 1/6, now the temperature ofsink is reduced by 6 2^{o} C, then this ratio becomes twice, therefore the initial temperature ofthe sink and source are respectively$ (1) $3 3^{o} C, 6 7^{o} C$ (2) $3 7^{o} C, 9 9^{o} C$ (3) $6 7^{o} C, 3 3^{o} C$ (4) $97 K, 37 K.$ 341. $One mole of an ideal monatomic gas undergoes a process described by the equation P V^{3} = constant. The heat capacity ofthe gas during this process is$ (1) $3 2 R$ (2) $5 2 R$ (3) $2 R$ (4) $R$ 342. $Density of water at 4^{\circ} C and 20^{\circ} C are 1000 kg / m^{3} and 998 kg / m^{3} respectively. The increase in internal energy of 4 kg of water when it is heated from 4^{\circ} C to 20^{\circ} C is____J. (specific heat capacity of water = 4.2 J / kg . and 1 atmospheric pressure = 10^{5} Pa)$ (1) $234699.2$ (2) $315826.2$ (3) $258700.8$ (4) $268799.2$ 343. $The temperature of reservoir of Carnot's engine operating with an efficiency of 70% is 1000K. The temperature of its sink is$ (1) $300 K$ (2) $400 K$ (3) $500 K$ (4) $700 K$ 344. $10 mole of an ideal gas is undergoing the process shown in the figure. The heat involved in the process from P_{1} to P_{2} is α Joule (P_{1} = 21.7 Pa and P_{2} = 30 Pa, C_{v} = 21 J / K . mol, R = 8.3 J / mol . K). The value of α is____.$ (1) $21$ (2) $15$ (3) $28$ (4) $24$ 345. $Figure below shows two paths that may be taken by a gas to go from a state A to a state C . In process AB, 400 J of heat is added to the system and in process BC, 100 J ofheat is added to the system. The heat absorbed by the system in the process AC will be$ (1) $460 J$ (2) $300 J$ (3) $380 J$ (4) $500 J$ 346. $The p - V diagram shown below indicates two paths along which a sample of gas can be taken from state A to state B . The energy equal to 5 pV in the form of heat is required to be transferred, if the Path-I is chosen. How much energy in the form of heat should be transferred, if Path-2 is chosen?$ (1) $\frac{11}{2} pV$ (2) $6 pV$ (3) $\frac{9}{2} pV$ (4) $7 pV$ 347. $A Carnot engine with efficiency 50% takes heat from a source at 600 K. In order to increase the efficiency to 70%, keeping the temperature of sink same, the new temperature of the source will be:$ (1) $360K$ (2) $1000 K$ (3) $900K$ (4) $300K$ 348. $A quantity of monoatomic gas undergoes a process in which pressure is changed linearly with volume. The pressure and volume are changed from initial value (P_{0}, V_{0}) to final value (3 P_{0}, 3 V_{0}) . The heat absorbed by the gas during process is$ (1) $8 P_{0} V_{0}$ (2) $12 P_{0} V_{0}$ (3) $16 P_{0} V_{0}$ (4) $20 P_{0} V_{0}$ 349. $A system goes from A and B via two processes I and II as shown in figure. If Δ U_{1} and Δ U_{2} are the ρ changes in internal energies in the processes I and II respectively, then the relation between Δ U_{1} and Δ U_{2} is$ (1) $Δ U_{1} = Δ U_{2}$ (2) $Δ U_{2} < Δ U_{1}$ (3) $Δ U_{2} > Δ U_{1}$ (4) $undetermined$ 350. $One mole of an ideal gas is taken from A to B, from B to C and then back to A . The variation of its volume with temperature for that change is as shown. Its pressure at A is P_{0}, volume is V_{0} . Then, the internal energy$ (1) $at A is more than at B$ (2) $at C is less than at B$ (3) $at B is more than at A$ (4) $at A and B are equal$ 351. $A graph of pressure versus volume for an ideal gas for different processes is as shown. In the graph curve OC represents$ (1) $isochoric process$ (2) $isothermal process$ (3) $isobaric process$ (4) $adiabatic process.$ 352. $A real gas within a closed chamber at 27^{\circ} C undergoes the cyclic process as shown in figure. The gas obeys P V^{3} = RT equation for the path A to B . The net work done in the complete cycle is (assuming R = 8 J / molK) :$ (1) $20 J$ (2) $205 J$ (3) $-20 J$ (4) $225 J$ 353. $Three different processes that can occur in an ideal monoatomic gas are shown in the P vs V diagram. The paths are labelled as A \to B, A \to C and A \to D The change in internal energies during these process are taken as E_{AB}, E_{AC} and E_{AD} and the work done as W_{AB} W_{AC} and W_{AD} The correct relation between these parameters are$ (1) $E_{AB} < E_{AC} < E_{AD}, W_{AB} > 0, W_{AC} > W_{AD}$ (2) $E_{AB} = E_{AC} = E_{AD}, W_{AB} > 0, W_{AC} = 0, W_{AD} > 0$ (3) $E_{AB} > E_{AC} > E_{AD}, W_{AB} < W_{AC} < W_{AD}$ (4) $None of These$ 354. $An ideal gas goes from state A to state B via three different processes as indicated in the P‐V diagram. If Q_{1}, Q_{2}, Q_{3} indicate the heat absorbed by the gas along the three processes and Δ U_{1}, Δ U_{2}, Δ U_{3} indicate the change in internal energy along the three processes respectively, then$ (1) $Q_{1} > Q_{2} > Q_{3} and Δ U_{1} = Δ U_{2} = Δ U_{3}$ (2) $Q_{3} > Q_{2} > Q_{1} and Δ u_{1} = Δ u_{2} = Δ u_{3}$ (3) $Q_{1} = Q_{2} = Q_{3} and Δ u_{1} > Δ u_{2} > Δ u_{3}$ (4) $Q_{3} > Q_{2} > Q_{1} and Δ u_{1} > Δ u_{2} > Δ u_{3}$ 355. $A thermodynamic system is taken through cyclic process. The total work done in the process is:$ (1) $200 J$ (2) $300 J$ (3) $100 J$ (4) $Zero$ 356. $In 1^{s t} case, Carnot engine operates between temperatures 300 K and 100 K. In 2^{n d} case, as shown in the figure, a combination of two engines is used. The efficiency of this combination (in 2^{n d} case) will be:$ (1) $same as the 1^{s t} case$ (2) $always greater than the 1^{s t} case$ (3) $always less than the 1^{s t} case$ (4) $may increase or decrease with respect to the 1^{s t} case$ 357. $A gas is compressed isothermally to half of its initial volume. The same gas is compressed separately through an adiabatic process until its volume is again reduced to half. Then, [NEET 2016]$ (1) $compressing the gas through adiabatic process will require more work to be done.$ (2) $compressing the gas isothermally or adiabatically will require the same amount of work.$ (3) $which of the case (whether compression through isothermal or through adiabatic process) requires more work will depend upon the atomicity of the gas.$ (4) $compressing the gas isothermally will require more work to be done.$ 358. $The volume (V) of a monoatomic gas varies with its temperature (T), as shown in the graph. The ratio of work done by the gas to the heat absorbed by it when it undergoes a change from state A to state B is [NEET 2018]$ (1) $\frac{1}{3}$ (2) $\frac{2}{3}$ (3) $\frac{2}{5}$ (4) $\frac{2}{7}$ 359. $A bimetallic strip is made of aluminium and steel (α_{Al} > α_{steel}) . On heating, the strip will$ (1) $remain straight$ (2) $get twisted$ (3) $bend with aluminium on concave side$ (4) $bend with steel on concave side$ 360. $In the reported figure, heat energy absorbed by a system in going through a cyclic process is ___πJ$