Thermodynamics PYQs Set 14 (PDF)

Set 14 of 17 · Questions 391-420 of 484

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Mere Teacher · Previous Year Questions JEE Main Physics · Thermodynamics · Set 14 (Q391-420)
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391. $In the given (V - T) diagram, what is the relation between pressures P_{1} and P_{2} ?$ (1) $P_{2} < P_{1}$ (2) $Cannot be predicted$ (3) $P_{2} = P_{1}$ (4) $P_{2} > P_{1}$ 392. $The net work done by an ideal gas going through the cycle as shown in the P - V diagram below is$ (1) $0$ (2) $P_{1} V_{1}$ (3) $\frac{3}{2} P_{1} V_{1}$ (4) $\frac{1}{2} P_{1} V_{1}$ 393. $A system is taken from state a to state c by two paths adc and abc as shown in the figure. The internal energy at a is U_{a} = 10 J. Along the path adc the amount ofheat heat absorbed d Q_{1} = 50 J and the work obtained d W_{1} = 20 J whereas along the path abc the heat absorbed d Q_{2} = 36 J. The amount of work along the path abc is$ (1) $10 J$ (2) $12 J$ (3) $36 J$ (4) $6 J$ 394. $The P - V diagram of a Carnot's engine is shown in the graph below. The engine uses 1 mole of an ideal gas as working substance. From the graph, the area enclosed by the P - V diagram is [The heat supplied to the gas is 8000 J]$ (1) $1200 J$ (2) $2000 J$ (3) $3000 J$ (4) $1000 J$ 395. $A thermodynamic system undergoes a cyclic process ABC as shown in the diagram. The work done by the system per cycle is$ (1) $- 750 J$ (2) $750 J$ (3) $1250 J$ (4) $- 1250 J$ 396. $In the following p - V diagram the equation of state along the curved path is given by (V - 2)^{2} = 4 ap where a is a constant. The total work done in the closed path is$ (1) $+ \frac{1}{3 a}$ (2) $- \frac{1}{3 a}$ (3) $\frac{1}{2 a}$ (4) $- \frac{1}{a}$ 397. $An ideal gas is compressed to half its initial volume by means of several process. Which of the process results in the maximum work done on the gas?$ (1) $Adiabatic$ (2) $Isobaric$ (3) $Isochoric$ (4) $Isothermal$ 398. $A gas is taken through the cycle A \to B \to C \to A, as shown. What is the net work done by the gas?$ (1) $Zero$ (2) $- 2000 J$ (3) $2000 J$ (4) $1000 J$ 399. $An ideal gas is taken via path ABCA as shown in figure. The net workdone in the whole cycle is$ (1) $6 P_{1} V_{1}$ (2) $zero$ (3) $3 P_{1} V_{1}$ (4) $- 3 P_{1} V_{1}$ 400. $For a perfect gas, two pressures P_{1} and P_{2} are shown in figure. The graph shows:$ (1) $P_{1} > P_{2}$ (2) $P_{1} < P_{2}$ (3) $P_{1} - P_{2}$ (4) $Insufficient data to draw any conclusion$ 401. $Choose the correct statement for processes A ∖ & B shown in figure.$ (1) $PV^{γ} = k for process B and PV=k for process A.$ (2) $PV = k for process B and A .$ (3) $\frac{T ^{γ}}{p ^{γ - 1}} = k for process A and PV=k for process B.$ (4) $None of these$ 402. $The P - V diagram of a diatomic ideal gas system going under cyclic process as shown in figure. The work doneduring an adiabatic process CD is (use γ = 1.4) :$ (1) $- 500 J$ (2) $- 400 J$ (3) $400 J$ (4) $200 J$ 403. $A gas in a closed container undergoes the cycle ABCA as shown in the figure. The net heat released by the gas after it has undergone 20 cycles is$ (1) $3 kJ$ (2) $2 kJ$ (3) $1.5 kJ$ (4) $4.5 kJ$ 404. $P-T diagram of an ideal gas having three different densities ρ_{1}, ρ_{2}, ρ_{3} (in three different cases) is shown in the figure. Which of the following is correct:$ (1) $ρ_{1} > ρ_{2}$ (2) $ρ_{2} < ρ_{3}$ (3) $ρ_{1} = ρ_{2} = ρ_{3}$ (4) $ρ_{1} < ρ_{2}$ 405. $An ideal gas is compressed to half its initial volume by means of several processes. Which of the process results in the maximum work done on the gas?$ (1) $Isochoric$ (2) $Isothermal$ (3) $Adiabatic$ (4) $Isobaric$ 406. $A thermodynamic system undergoes cyclic process ABCDA as shown in figure. The work done by the system in the cycle is$ (1) $P_{0} V_{0}$ (2) $2 P_{0} V_{0}$ (3) $P_{0} V_{0} L$ (4) $zero$ 407. $A thermodynamic system is taken through the cycle abcda. The work done by the gas along the path bc is [NEET 2024]$ (1) $Zero$ (2) $30 J$ (3) $-90 J$ (4) $-60 J$ 408. $In the reported figure, there is a cyclic process ABCDA on a sample of 1 mol of a diatomic gas. The temperature of the gas during the process A \to B and C \to D are T_{1} and T2 (T_{1} >T2) respectively. Choose the correct option out of the following for work done if processes BC and DA are adiabatic.$ (1) $W_{AB} = W_{DC}$ (2) $W_{AD} = W_{BC}$ (3) $W_{BC} + W_{DA} > 0$ (4) $W_{AB} < W_{CD}$ 409. $A composite slab is prepared with two different materials A and B . The relation between their coefficient of thermal conductivity and thickness is given as K_{A} = \frac{K _{B}}{2} and X_{A} = 2 X_{B}, respectively. If the temperature of faces of A and B are 75^{\circ} C and 50^{\circ} C respectively, what will be the temperature of common surface?$ (1) $75^{\circ} C$ (2) $50^{\circ} C$ (3) $55^{\circ} C$ (4) $125^{\circ} C$ 410. $A Carnot engine absorbs an amount Q of heat from a reservoir at an abosolute temperature T and rejects heat to a sink at a temperature of T/3. The amount of heat rejected is$ (1) $Q / 4$ (2) $Q / 3$ (3) $Q / 2$ (4) $2Q / 3$ 411. $The temperature-entropy diagram of a reversible engine cycle is given in the figure. Its efficiency is:$ (1) $\frac{1}{2}$ (2) $\frac{1}{4}$ (3) $\frac{1}{3}$ (4) $\frac{2}{3}$ 412. $The volume (V) of a monatomic gas varies with its temperature (T), as shown in the graph. The ratio of work done by the gas, to the heat absorbed by it, when it undergoes a change from state A to state B, is$ (1) $\frac{2}{5}$ (2) $\frac{2}{3}$ (3) $\frac{1}{3}$ (4) $\frac{2}{7}$ 413. $Consider a heat engine as shown in figure Q1 and Q2 are heat added to heat bath T_{1} and heat taken from T_{2} in one cycle of engine. W is the mechanical work done on the engine. If W > 0, then possibilities are (i) Q1 > Q2 > 0 (ii) Q2 > Q1 > 0 (iii) Q2 < Q1 < 0 (iv) Q1 < 0, Q2 > 0$ (1) $(i) and (ii)$ (2) $(i) and (iii)$ (3) $(ii) and (iii)$ (4) $(ii) and (iv)$ 414. $The magnitude of heat exchanged by a system for the given cyclic process ABCA (as shown in figure) is (in SI unit):$ (1) $5 π$ (2) $40 π$ (3) $10 π$ (4) $zero$ 415. $A sample of gas expands from volume V_{1} to V_{2} . The amount of work done by the gas is greatest, when the expansion is$ (1) $adiabatic$ (2) $equal in all cases$ (3) $isothermal$ (4) $isobaric.$ 416. $An ideal gas is taken through the cycle A \to B \to C \to A as shown in the figure. If the net heat supplied to the gas in the cycle is 5 J . The magnitude of work done during the process C \to A is$ (1) $5 J$ (2) $10 J$ (3) $15 J$ (4) $20 J$ 417. $A Carnot engine whose heat sinks at 27°C, has an efficiency of 25%. By how many degrees should the temperature of the source be changed to increase the efficiency by 100% of the original efficiency?$ (1) $Increases by 18°C$ (2) $Increase by 200°C$ (3) $Increase by 120°C$ (4) $Increase by 73°$ 418. $The graph between two temperature scales P and Q is shown in the figure. Between upper fixed point and lower fixed point there are 150 equal divisions of scale P and 100 divisions on scale Q. The relationship for conversion between the two scales is given by:$ (1) $\frac{t _{Q}}{150} = \frac{t _{P} - 180}{100}$ (2) $_\frac{t _{Q}}{100} = \frac{t _{P} - 30}{150}$ (3) $\frac{t _{P}}{180} = \frac{t _{Q} - 40}{100}$ (4) $\frac{t _{P}}{100} = \frac{t _{Q} - 180}{150}$ 419. $One mole of an ideal gas at 270C is taken from A to B as shown in the given PV indicator diagram. The work done by the system will be\dots\dots x10-1J. [Given: R = 8.3 J / moleK, ln 2 = 0.6931] (Round off to the nearest integer)$ 420. $A heat engine operates with the cold reservoir at temperature 324 K. The minimum temperature of the hot reservoir, if the heat engine takes 300 J heat from the hot reservoir and delivers 180 J heat to the cold reservoir per cycle, is___________K.$