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24. An engineer claims to have made an engine delivering 10 kW power with fuel consumption of 1 g/sec. The calorific value of the fuel is 2 kcal/g. Is the claim of the engineer

(a) Valid (b) Invalid (c) Depends on engine design (d) Depends of the load Answer-b (2)

23. A reversible engine converts one-sixth of the heat input into work. When the temperature of the sink is reduced by 62°C, the efficiency of the engine is doubled. The temperatures of the source and sink are

(a) 80°C, 37°C (b) 95°C, 28°C (c) 90°C, 37°C (d) 99°C, 37°C Answer-d (4)

22.A thermally insulated rigid container contains an ideal gas heated by a filament of resistance 100Ω through a current of 1A for 5 min then change in internal energy is

(a) 0 kJ (b) 10 kJ (c) 20 kJ (d) 30 kJ Answer-d (8)

21. Initial pressure and volume of a gas are P and V respectively. First it is expanded isothermally to volume 4V and then compressed adiabatically to volume V. The final pressure of gas will be

(a) 1P (b) 2P (c) 4P (d) 8P Answer-b (6)

20. Two samples A and B of a gas initially at the same pressure and temperature are compressed from volume V to V/2 (A isothermally and adiabatically). The final pressure of A is

(a) Greater than the final pressure of B (b) Equal to the final pressure of B (c) Less than the final pressure of B (d) Twice the final pressure of B Answer-c (9)

19.Which one of the following gases possesses the largest internal energy

(a) 2 moles of helium occupying 1m3 at 300 K (b) 56 kg of nitrogen at 107N/m2 and 300 K (c) 8 grams of oxygen at 8 atm and 300 K (d) 6×1026 molecules of argon occupying 40m3 at …

18. When an ideal gas (γ=5/3 ) is heated under constant pressure, then what percentage of given heat energy will be utilised in doing external work

(a) 40 % (b) 30 % (c) 60 % (d) 20 % Answer-a (8)

17. When an ideal monoatomic gas is heated at constant pressure, fraction of heat energy supplied which increases the internal energy of gas, is

(a) 2/5 (b) 3/5 (c) 3/7 …

16. Two Carnot engines A and B are operated in succession. The first one, A receives heat from a source at

T1=800K and rejects to sink at T2K . The second engine B receives heat rejected by the first engine and rejects to another sink at T3=300K. If the work outputs of two engines are equal, then the value of T2 …

15. The temperature of a hypothetical gas increases to √2 times when compressed adiabatically to half the volume. Its equation can be written as

(a) PV3/2 = constant (b) PV5/2 = constant (c) PV7/3 = constant (d) PV4/3 = constant Answer-a (6)

14. The volume of air increases by 5% in its adiabatic expansion. The percentage decrease in its pressure will be

(a) 5% (b) 6% (c) 7% (d) 8% Answer-c (2)

13. An insulator container contains 4 moles of an ideal diatomic gas at temperature T. Heat Q is supplied to this gas, due to which 2 moles of the gas are dissociated into atoms but temperature of the gas remains constant. Then

(a) Q = 2RT (b) Q=RT (c) Q= 3RT (d) Q= 4RT Ans. b (3)

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NEET Topper Interview

PUBLIC NOTICE 25 August 2024 Sub: Information Regarding Challenge of Provisional Answer Key, Display of Scanned Images of OMR Answer Sheet and Display of Recorded Response for National Eligibility cum Entrance Test (UG) – 2024 – Reg. National Testing Agency …

The molar heat capacity in a process of a diatomic gas if it does a work of Q/4 when a heat of Q is supplied to it is

(a) (2/5)R (b) (5/2)R (c) (10/3)R (d) (6/7)R Ans. c (9)

11. A cylindrical tube of uniform cross-sectional area A is fitted with two air tight frictionless pistons.

temperature is T0, atmospheric pressure is also P0. Now the temperature of the gas is increased to 2T0, the tension in the wire will be (a) 2P0A …

10. Work done by a system under isothermal change from a

volume V1 to V2 for a gas which obeys Vander Waal’s equation (V – βn)[ P + (αn2/v)= nRT (a) nRT loge( V2 – nβ/V1– nβ) + α n2(V1 -V2)/V1V2 (b) nRT log10 ( V2 – αβ/V1– αβ) + α n2(V1 -V2)/V1V2 …

9. An ideal gas expands isothermally from a

(a) P3 > P1 , W > 0 (b) P3 < P1 , W < 0 (c) P3 > P1 , W < 0 (d) P3 = P1 , W = 0 Ans. …

8. A gas mixture consists of 2 moles of oxygen and 4 moles argon at temperature T. Neglecting all vibrational modes, the total internal energy of the system is

(a) 4 RT (b) 15 RT (c) 9 RT (d) 11 RT Ans. d (6)

15. The temperature of a hypothetical gas increases to √2 times when compressed adiabatically to half the volume. Its equation can be written as

(a) PV3/2 = constant (b) PV5/2 = constant (c) PV7/3 = constant (d) PV4/3= constant Answer-a (7)

14. The volume of air increases by 5% in its adiabatic expansion. The percentage decrease in its pressure will be

(a) 5% (b) 6% (c) 7% (d) 8% Answer-c (4)

13. An insulator container contains 4 moles of an ideal diatomic gas at temperature T. Heat Q is supplied to this gas, due to which 2 moles of the gas are dissociated into atoms but temperature of the gas remains constant. Then

(a) Q=2RT (b) Q=RT (c) Q=3RT (d) Q=4RT Answer-b (7)

12. The molar heat capacity in a process of a diatomic gas if it does a work of Q/4 when a heat of Q is supplied to it is

(a) (2/5)R (b) (5/2)R (c) (10/3)R (d) …

11. A cylindrical tube of uniform cross-sectional area A is fitted with two air tight frictionless pistons. The pistons are connected to each other by a metallic wire. Initially the pressure of the gas is

P0 and temperature is T0, atmospheric pressure is also P0. Now the temperature of the gas is increased to 2T0, the tension in the wire will be (a) 2P0 A …

10. Work done by a system under isothermal change from a volume

V1 to V2 for a gas which obeys Vander Waal’s equation (V-βn)[P+(αn2/V)]=nRT (a) nRT loge [ (V2-nβ)/( V1-nβ) ]+αn2[(V1 – V2)/(V1 V2)] (b) nRT log10 [ (V2-nβ)/( V1-nβ) ]+αn2[(V1 – V2)/(V1 V2)] (c) nRT loge [ (V2-nα)/( V1-nα) ]+βn2[(V1 – V2)/(V1 V2)] (d) …

9. An ideal gas expands isothermally from a volume

V1 to V2 and then compressed to original volume V1 adiabatically. Initial pressure is P1 and final pressure is P3 . The total work done is W. Then (a) P3 > P1 ,W > 0 …

8. A gas mixture consists of 2 moles of oxygen and 4 moles argon at temperature T. Neglecting all vibrational modes, the total internal energy of the system is

(a) 4 RT (b) 15 RT (c) 9 RT (d) 11 RT Answer-d (3)

7. A mono atomic gas is supplied the heat Q very slowly keeping the pressure constant. The work done by the gas will be

(a) (2/3)Q (b) (3/5)Q (c) (2/5) Q (d)(1/5)Q Ans. c (9)

A closed hollow insulated cylinder is filled with gas

at 00C and also contains an insulated piston of negligible weight and negligible thickness at the middle point. The gas on one side of the piston is heated to 1000c. If the piston moves 5cm the length of the hollow …

5. A monoatomic ideal gas, initially at temperature

T1, is enclosed in a cylinder fitted with a frictionless piston. The gas is allowed to expand adiabatically to a temperature. T2 by releasing the piston suddenly. If L1 and L2 are the lengths of the gas column before and …

4. Two identical containers A and B with frictionless pistons contain the same ideal gas at the same temperature and the same volume V.

The mass of the gas in A is mB and that in B is . The gas in each cylinder is now allowed to expand isothermally to the same final volume 2V. The changes in the pressure in A and …

34. Which of the following processes is reversible

(a) Transfer of heat by radiation (b) Electrical heating of a nichrome wire (c) Transfer of heat by conduction (d) Isothermal compression Ans. d (16)

3. During the melting of a slab of ice at 273 K at atmospheric pressure

(a) Positive work is done by ice-water system on the atmosphere (b) Positive work is done on the ice-water system by the atmosphere (c) The internal energy of the ice-water system increases (d) The internal energy of the ice-water system …

2. 1cm3 of water at its boiling point absorbs 540 calories of heat to become steam with a

volume of 1671 cm3 .If the atmospheric pressure = 1.013 x 105 N/m3 and the mechanical equivalent of heat = 4.19 J/calorie , the energy spent in this process in overcoming intermolecular forces is (a) 540 cal (b) 40 cal …