Thermodynamics Questions and Answers

1 R 17 Specific 1 3R capacity of a solid is 2 2R 3 3R heat capacity of water is 2 6R 3 5R 4 4R 4 9R Uch Stol 1 R SHI Bird 1 3R 2 2R 17 fafence 3 enfan 2 6R 3 3R 3 5R 4 4R 4 9R

A diatomic ideal gas is used in a car engine as the working substance If during the adiabatic expansion part of the cycle volume of the gas increases from V to 32 V the efficiency of the engine is ow

During adiabatic expansion of 2 moles of a gas the change in internal energy was found to b equal to 100 J The work done during the process will be equal to i wodoo 100 arves 2 3rd e Jaws Soys Jy wo woddaw 3o vous dod 35 28hod Options Zero 1 Bo 2 200 J 3 100 J 100 T

A gas consisting of rigid molecules expands adiabatically such that r m s speed of its molecules becomes half The ratio of final and initial volumes of the gas is ratio of specific heat capacities of the gas is 1 5 4 mox 500S as rows som Jo Bobby Forms 58 SKO OSA J n u 50 453 rero d y Jogge 1 5 www android universityupdates in www universityupdates in www ios universityupdates in www android previousquestionpapers com www previousquestionpapers com www ios previousquestionpapers Options 1 16 1 21 16 3 4 1

An insulated box containing a diatomic gas of molar mass M is moving with a velocity v The box is suddenly stopped The resulting change in temperature is 1 3 Mv 2R My 5R 2 4 Mv 3R 2Mv 5R

A rigid container has a hole in its wall When some air is filled in it at 27 C weight of air in it is 100 gm Now the temperature of air inside is increased by AT the weight of air becomes 50 gm AT should be 27 C C O 300 C 327 C

e figue shows an equiconcave lens placed on a plane mirror The focal length of lens in air is 30 cm e refractive index of lens is 1 5 and that of liquid is 2 The combination behaves as A A concave mirror of focal length 15 cm C A concave mirror of focal length 10 cm B A convex mirror of focal length 15 cm D A convex mirror of focal length 20 cm 1000001

Six moles of an ideal gas perfomrs a cycle shown in figure If the temperature are TA 600 K TB 800K Tc 2200 K and TD 1200K the work done per cycle is P4 B C Question Type Single Correct Type 1 20 kJ 230 kJ T

A certain mono atomic gas undergoes the process PV Here Q Heat supplied to the gas W work done by the gas AU change in internal energy of the gas The ratio for the process will be 2 The ratio IfAT W AU The molar specific heat capacity for the process is R for the process will be 1 3 Constant 100K and AU is 450 R joules then the number of moles of the gas must be 3

A heat engine employing a carnot cycle with an efficiency of n 10 is used as a refrigerating machine with the same thermal reservoirs Then its coefficient of performance is A 3 C 7 B 5 D 9

A cylinder of 0 9 m in volume contains air at 0 C and 39 24 N cm2 absolute pressure The air compressed to 0 45 m Find i the pressure inside the cylinder assuming isothermal proces ii pressure and temperature assuming adiabatic process Take k 1 4 for air Ans i 78 48 N cm ii 103 5 N m 140 C

One mole of an ideal the process AB as shown in the T V indicator diagram If volume of the system changes from Vo to 0 2V then the amount of heat transferred to the system is 5RV a c 2 5RaV 0 RT In 2 monoatomic gas undergoes T To 0 b RT ln2 d V 0 0 2 3RaV B tan0 a 2V0 3RV RT In2 V RT ln 2

Problem 7 8 A certain cloud consists mostly of supercooled wa ter droplets at 10 C and maintains the ambient air at saturation with respect to liquid water at that temperature Compute the su persaturation in percent with respect to a solitary ice particle that spontaneously forms in the cloud Answer 10

Which of the following is always true regarding the change in entropy of an ideal gas during an isothermal process The change in entropy depends only on the amount of heat transferred The change in entropy is inversely proportional to the temperature The change in entropy is positive The change in entropy is negative

Which of the following options is are true for the given phase transformation curve of the ice water steam system if Q cal s heat is supplied to it Take L 80 cal g L 540 cal g 1 A 4 1 B 1 1 C 1 1 D Cannot relate I and I from the graph T C 100 0 50 S s 1 1 g 9 t s

2 10 6 N m 4 16 3 N m 3 40 N m 13 A scientist claims to have developed efficient engine while 13 working between 27 C and 327 C Then efficiency of engine will be 1 70 2 60 1 70 3 56 506 Ti74 4 40 3 56 d 4 The value of acceleration due to gravity g at a depth d s 14 one third of its value on the earth s surface The value of dis DE Uo R 10 be d 1 24 N m 3 40 N m 270 Seat RS d 1

In a reversible thermodynamic process undergone by a fixed amount 2 moles of diatomic gas molar heat capacity remained constant When the temperature of the gas changes from To to 2T as shown in the graph Take R to be universal gas constant Initial pressure of gas Po 1 Work done by the gas during process AB is A RTO B 3 RTO C 5 RTO ct 3R To D 6 RT

The pV diagram shown is for 7 50 moles of an ideal diatomic gas taken through a cycle from A to B to C The ideal gas constant is R 8 314 J mol K How much heat is exchanged with the gas during the BC part of the cycle p Pax 10 D 5 00 3 00 Select one a 30 kJ b 4 kJ c 4 kJ a 0 200 1 T b 0 600 V m

A gas undergoes following process Ab Compressed to half of the initial volume P x V Bc CD No Isothermal expansion to intial volume Adiabatic process such that PD PA Select incorrect statemen Net heat is released AUAB 0 AUCD 0

An isolated system is one in which Mass does not cross boundaries of the system though energy may do so Neither mass nor energy crosses the boundaries of the system Both energy and mass cross the boundaries of the system Mass crosses the boundary but not the energy

103 In the figure shown one of the curves is for adiabatic process and one the curves is for isothermal process The most probable curve for adiabatic process is given by the curve PECAB A AB C EF B CD D All of them

The temperature difference between the hot and cold end of a thermally conducted body is increased from 10 C to 20 C then thermal conductivity of body b becomes double d becomes four times at the end of the next 10 minutes 000 in 19 minutes If the room temperature is 25 C and assuming a remains constant c becomes half

Calculate the radius r of a circular spot of liquid after 25 seconds The droplet volume is 5 5 mL 3 The liquid has density 970 kg m and dynamic viscosity 0 106 Pa s The droplet has an initial height which is larger than the capillary length of the liquid The acceleration due to gravity is 9 81 m s 2 Give your answer in mm show your working

10 A carnot engine having an efficiency of t of heat engine is used as a refrigerator If the work done on the system is 10 J the amount of energy absorbed from the reservoir at lower temperature is a 1 J b 90 J c 99 J d 10 I

b The graph in Fig 5 1 shows the variation of temperature with time for a substance that is initially liquid temperature A B time Fig 5 1 i State what is taking place at points A B and C You should say what changes of state if any are taking place point A point B point C

The Sun has a surface temperature of 5778 K and a radius a 6 96x108 m The Sun is at an average distance of 1 5x10 1 m from the Earth If the Sun s temperature were to increase by 224 K calculate the Solar Insolation at the Earth in W m 2

44 A sphere of radius R at temperature T radiates according to Stephan s law at the rate of H J sec R The rate of radiation of a similar sphere of radius at temperature 27 will be Assuming both spheres to be ideal black body 1 Ho 3 4H 2 109 26 4 256H

If minimum possible work is done by a refrigerator in converting 100 grams of water at 0 C to ice how much heat in calories is released to the surroundings at temperature 27 C Latent heat of ice 80 Cal gram to the nearest integer

18 An electric refrigerator extracts 2000 calories from ice tray The coefficient of performance is 5 Then work done by the compressor in Joule will be 2 1680 joules 4 2000 joules 1 400 joules 3 800 joules

a 12 5 10 C E 200 GPa If the rod fitted strongly between the supports as shown in the figure is heated the stress induced in it due to 20 C rise in temperature will be IES 1999 a 0 07945 MPa b 0 07945 MPa c 0 03972 MPa d 0 03972 MPa

13 A refrigerator works between 4 C and 30 C It is required to remove 600 calories of heat to keep the every second in order temperature of the refrigerated space constant The power required is Take 1 cal 4 2 Joules a 23 65 W b 236 5 W c 2365 W 1 OOF W n 2 1 Tc TH

5 The first law of thermodynamics is concerned with the 1 Conservation of momentum 3 Conservation of mass 1 3 2 Conservation of energy 4 Conservation of temperature 2 f 4

7 50 g ice at 0 C is dropped into a calorimeter containing 100 g water at 30 C If thermal capacity of calorimeter is zero then amount of ice left in the mixture at equilibrium is 50 g 100 g 1 12 5 g 2 25 g 3 20 g 30 C f 4 10 g

shown in the figure A to B the correct option is P 4 Po Po B Vs 3V 1 Temperature first decreases then increases 2 Temperature first increases and then decreases 3 Temperature will continuously decrease 4 Temperatur or

A PV diagram for a thermody shown in he figure Then for the process choose the correct option PA 4P Pa A B V 3V 1 Temperature remains constant through out 2 Temperature continuously increases 3 Temperature first decreases then continuously increases 4 Temperature first increases then cont nuously decreases

1 1 2 3 1 4 Q 19 CST 02 1 5 m Rough Surface 213 4 1 5 Thermodynamic state variables Equation of state 4P Po PV diagram for a thermodynamic process is shown in fgure Then choose the correct option during the process A Smooth Vo B 4 1 Temperature continuously decreases 2 Temperature continuously increases 3 Temperature first decreases and then again increases 4 Temperature first increases and then decreases 1 2

5A PV diagram for a thermodynamical process is shown in the figure Then during process from A to B choose the correct option 3P Po B A V 2Vc 1 Temperature continuously falls 2 Temperature first falls ther rises 3 Temperature first rises then falls

No 15 View In English Six moles of an ideal gas perfomrs a cycle shown in figure If the temperature are TA 600 K TB 800K TC 2200 K and To 1200K the work done per cy is 1 2 3 4 Correct Answer 3 20 kJ 30 kJ 40 KJ 60 kJ

A piston containing an ideal gas is originally in the state X see figure The gas is taken through a thermal cycle X Y X as shown The work done by the gas is positive if the direction of the thermal cycle is a clockwise b counter clockwise c neither clockwise nor counter clockwise d clockwise from X Y and counter clockwise from Y X P X Y

A second order phase transition is one in which a the plot of entropy as a function of temperature shows a discontinuity b the plot of specific heat as a function of temperature shows a discontinuity c the plot of valume as a function of pressure shows a discontinuity d the plot of comprehensibility as a function of temperature is continuous

One mole of diatomic ideal gas undergoes a cyclic process ABC as shown in figure The process BC is adiabatic The temperatures at A B and C are 400 K 800 K and 600 K respectively Choose the correct statement 1 The change in internal energy in the process AB is 350 R 2 The change in internal energy in the process BC is 500 R 3 The change in internal energy in whole cyclic process is 250 R The change in internal enorm in the process CA is 700 P P A B 800 K 400 K 600 E C

2 moles of He and 2 moles of O2 are mixed with each other 100R R universal gas constant amount of heat energy is supplied to the gas sample through different processes which are given by expression in List and List Il contains rise in temperature in different processes as given in List l Choose the correct option Symbols given have their usual meanings 2 H 2 0 tg 2 fhul vildl137 f27 f27U P Q mu af zerf 1 ad f geu c aya Al AA 347 444 44 List 1 R S A B C D dp dT dP dV dT dV P T 1 P 2 V P Pressure ra ut mu Afaa 7 u thai c 100R R Hidd tu fu T V 2 3 4 1 a f 1 3 1 zffa fa fHa uxo P 5 Q P 3 Q p Density a 1 List 11 Zero 2 25 K 3 25 K P 1 Q 1 Q 5 R 1 S 3 1 4 25 K 6 5 R 1 S 3 5 2 K 4 5 R 2 S 2 P 3 Q 5 R 1 S 2 Correct Answer

2 A vertical U tube is completely filled with a liquid of density p The inner cross section area of each of the vertical arms of the U tube is S total volume of both the arms is Vo and volume of bottom arm is negligible Both the ends of the tube are of the same height One of them is open to the atmosphere and the other one is hermetically connected to a flask of volume Vo filled with an ideal mono atomic gas Find the amount of heat which must be given to the gas to drive slowly half of the liquid out of the tube The atmospheric pressure is constant and equal to po Pressure of liquid vapors effects of surface tension and heat loss to the environment are negligible Acceleration due to gravity

One mole of a diatomic ideal gas is taken through a cyclic process starting from point A The process A B is an adiabatic compression B C is isobaric expansion C expansion and D A is isochoric respectively The volume ratios are given to be Vc 16 and 2 and the VB VA VB temperature at A is TA D an adiabatic 300 K Find the efficiency of the cyclic process in

Two identical breakers A and B contain equal volumes of two different liquids at 60 C each and left to cool down Liquid in A has density of 8 x 102 kg m and specific heat of 2000 J kg K while liquid in B has density of 103 kg m and specific heat of 4000 J kg K Which of the following best describes their temperature versus time graph schematically assume the emissivity of both the beakers to be the same 3 A 60 C T Exam com

2 48 A diatomic ideal gas is used in a Carnot engine as the working substance If during the adiabatic expansion part of the cycle volume of the gas increases from V to 32 V the efficiency of the engine is 1 0 5 0 99 12 0 75 4 0 25

The diagram shows the P V diagram of a cyclic process ABCA P Nm 2 10 6 2 THE N A Work done in process A Bis 0 036 J B Work done in process B Cis 0 024 J C Work done in process C Ais zero D Work done in cycle ABCA is 0 06 J 0 6 8 10 12 V litre GRO

The specific heats Cp and C of a diatomic gas A are 29 J mol K and 22 J mol 1 K 1 respectively Another diatomic gas B has the corresponding values as 30 J mol 1 K 1 and 21 J mol 1 K 1 respectively Which among the following is correct Question Type Single Correct Type 1 2 A has one vibrational degree of freedom and B has two vibrational degrees of freedom A has one vibrational degree of freedom and B has zero vibrational degree of freedom

A gas is expanded from volume V to volume V2 in three processes shown in the figure If U U Uc and Up represent the internal energies of the gas in state A B C and D respectively the which of the following is not correct P V 1 1 UB UA 0 3 UD UA 0 Isobaric Isothermal Adiabatic V B D 2 2 UC UA 0 4 UB Uc UD

28 A diatomic molecule can be modelled as two rigid balls connected with spring such that the balls can vibrate with respect to centre of mass of the system spring balls Consider a diatomic gas made of such diatomic molecule If the gas performs 20 Joule of work under isobaric condition then heat given to the gas is J