Thermodynamics Questions and Answers

The pressure P of n moles of an ideal gas varies with volume V as P a bV2 where a and b are positive constants The highest absolute temperature to which the gas can be heated is Tmax Tmax Tmax a 2 nR 3b 2a 2 3n R 3b R gas constant a At Tmax V 7 1 2

What is the entropy change when I mole oxygen gas expands isothermally and reversibly from an initial volume of 10 L to 100 L at 300 K 300 R RR Rada A 19 14J K 1 GRAGA I CHI Ych A B 109 12 J K 1 C 29 12 J K 1 10 L 100 4 3 k

ideal diatomic gas goes through a cycle consisting of two isochoric and two isobaric lines The slute temperature of the gas rises 5 times both in the isochoric heating and in the isobaric expansion iciency of such a cycle is

Question 7 The temperature dependence of the resistance of a non linear resistor is investigated in a laboratory having constant ambient temperature To 20 C As the temperature is raised to T 100 C the resistance changes abruptly from R 5052 to R 10052 On cooling the reverse abrupt change from 10092 5022 to takes place at T 90 C When a voltage V 80 volt is applied to the resistor a periodically varying current is established in the circuit after some time Assume Newton s law of cooling is applicable to the resistor this proportionally constant being d 1 2 Jk s The heat capacity of the resistor is c 3 J K Now answer the following questions The time period of the current oscillation is Options a 0 1 sec b 2 sec c 0 3 sec 604

An ideal gas expands isothermally from a volume V to V and then compressed to original volume V adiabatically Initial pressure is P and final pressure is P3 The total work done is W Then Question Type Single Correct Type 1 P3 P1 W 0 2 P3 P1 W 0 3 P3 P1 W 0

7 10 An incompressible liquid flows through a horizontal tube as shown in the figure 7 78 Then the velocity v of the fluid is A meter A 3 0 m s 3 0 m s A meter Figure 7 78 20 B 1 5 m s v 1 5 m s 1 5 A meter v

A heat engine uses one mole of an ideal monatomic gas as a working substance The engine can follow either cycle A or cycle B in the diagram The ratio of the efficiencies of the cycles is eA eB 4 If the value of eA eg is Find the value of n P Cycle A A 4 D Cycle B 2V 3V 4V SV

Six moles of O gas is heated from 20 C to 35 C at constant volume If specific heat capacity at constant pressure is 8 cal mol 1 K 1 and R 8 31 J mol K 1 then what is change in internal energy of gas Question Type Single Correct Type 1 180 cal 2 300 cal 3 360 cal

The contents of a well insulated tank are system heated by a resistor of 23 ohm in which 10 A current is flowing Consider the tank along with its contents as a thermodynamic The work done by the system and the heat transfer to the system are positive The rates of heat Q work W and change in internal energy AU during the process in kW are

A certain amount of an ideal gas initially at a pressure P and temperature T First it undergoes a constant pressure process 1 2 such that T 3T 4 Then it undergoes a constant volume process 2 3 such that T3 T 2 The ratio of the final volume to the initial volume of the ideal gas is

Define the decay constant of radioactive gold 198 198Au used in imaging the structure of the liver if its half life is 2 67 days Select one O 0 26 1 s O 3 33x10 5 1 s O 3x10 6 1 s 221 10M 1 o

Suppose we double the temperature of a gas in a closed rigid container What happens to the pressure of the gas Select one O a It becomes quarter of its current value O b It decreases by half c It doubles d It quadruples

A monoatomic gas expands following a thermodynamic law P C V C Where C C2 are constants from state A Vo 3Po to B 3Vo Po What will be the volume of the gas upto which it absorbs heat A Vo B 2Vo

One mole of an ideal monoatomic gas at temperature To expands slowly according to the law P constant If the final temperature is 2To V heat supplied to the gas is Question Type Single Correct Type 1 2RTO 2 RTO 3 3 RTO 0

134 When temperature of a gas contained in closed vessel is increased by 5 C its pressure increases by 1 The original temperature of the gas was approximately 1 500 C 3 227 C 2 273 C 4 50 C

An ideal gas undergoes a cyclic process as shown in the given P T diagram where AC is adiabatic The process is also represented by A D P P B B D P U B B 2003

In isobaric process the ratio of increase in internal energy to the heat supplied for mono atomic gas is X In another isobaric process the ratio of work done to the heat supplied for diatomic gas is X2 X Then is X 200 7 3 21 10

32 gram of oxygen gas at temperature 27 C is compressed adiabatically to 1 3 of its initial volume Calculate the change in internal energy y 1 5 for oxygen consisting of one gram of hydrogen and turo

An ideal gas expands isothermally along AB and does 700 J of work a How much heat does the gas exchange along AB The gas expands adiabatically along BC and does 400 J of work When the gas returns to A along CA it exhusts 100 J of heat to its sur roundings How much work is done on the gas along this path b Solen Adu

A domestic refrigerator provides 80W of refrigeration at 18 C for the freezer and 40W of refrigeration at 5 C for the fresh food compartment The refrigerator is placed in a room which is maintained at 35 C The minimum power input in W

estion 19 2414011921 PCM Physics Camot s engine with its cold body at 17 C has 50 efficiency If the temperature of its hot body is now increased by 145 C the efficiency becomes D Click here to view this option Ref No 241401

2 kg of ice at 20 C is mixed with 5 kg of H O at 20 C in an insulating vessel having negligible heat capacity Calculate the final mass of water left in the container Given specific heat of water and ice 1 kcal kg C and 0 5kcalkg C and latent heat of fusion of ice is 80kcalkg

94 A Carnot engine whose efficiency is 40 takes in heat from a source maintained at a temperature of 500 K It is desired to have an engine of efficiency 60 Then the intake temperature for the same exhaust sink temperature must be a 1200 K b 750 K c 600 K d 800 K 501 energy from

Q 3 0 25 kg of air at a pressure of 140 kN m occupies 1 5 m and from this condition it is compressed to 1 4 MPa according to the law PV Constant Determine Change in internal energy of air The work done on or by the air Heat received or rejected by the air Take cp 1 005 kJ kg K cv 0 718 kJ kg K i ii iii

14 1 mole of He and 2 moles of O are contained in an adiabatic cylinder at pressures and temperatures as shown in figure If the adiabatic partition wall is removed then the final pressure will be a b C 1 mole He P T Po 13 13 16 Po Po Adiabatic partition wall 2 mole O Po T 2

14 1 mole of He and 2 moles of O2 are contained in an adiabatic cylinder at pressures and temperatures as shown in figure If the adiabatic partition wall is removed then the final pressure will be a b 1 mole He P To 12 72 Po 13 Po Po Adiabatic partition wall 2 mole O Po T 2

7 A calorimeter contains 10 g of water at 20 C The temperature falls to 15 C in 10 min When calorimeter contains 20 g of water at 20 C it takes 15 min for the temperature to become 15 C The water equivalent of the calorimeter is a 5 g b 10 g c 25 g d 50 g a

1 1 J PB 74 Two moles of helium gas undergo a cyclic process as shown in figure Assuming the gas to be ideal the net work done by the gas is 2 atm a 200RIn2 c 300RIn2 1 atm D 300 K 400 K b 100RIn2 d 400RIn2 mola of an id

the state passes through the critical point Determine a The volume of the vessel b The mass of liquid and ofxqug in the vessel initially Properties of Pure Substances S K Mondal Chapter 9 c The temperature of the mixture when the pressure has risen to 3 MPa

d 150 J of heat has been added to the gas 6 1 mole of an ideal gas ina cylindrical container p have the P V diagram as shown in figure If V 4V then the ratio of T temperatures will be T b a 112 c 312 A P V T PV constant B PVT d MI

3 At the same temperature will a gas of classical molecules a gas of boson or a gas of fermions exert the greatest pressure The least pressure Why 4 The peak wavelength in the spectrum of the radiation from a cavity is 3 Oum Find the

1 What is the enthalpy of a system with a diatomic gas whose pressure is 10 000 Pa and volume 20 L Enter your answer in Joules 2 A monatomic gas with internal energy 300 J housed in a chamber with pressure of 200 Pa flows adiabatically into another chamber where the pressure is only 100 Pa As a result the temperature of the gas decreases so it now has only 100 J of internal energy How much volume does the gas now take up Enter your answer in cubic meters

B 1 A closed system executes a quasi static process from an initial state 1 to a final state 2 absorbing Qu 80 kJ of heat and expanding from V 2 0 m to V 2 25 m against a constant pressure of p 0 15 MPa The system is brought back to its initial state by a non quasi static process during which it rejects Q 100 kul of heat What is the work done during the second process

10 Three cylindrical vessels identical in all respect except in their heights are completely filled with water Volumes of the first second and the third vessels are V 1 0 L V 2 0 L and V3 3 0 L respectively A heater can heat water of the first and the second vessels to maximum temperatures of 6 80 C and 2 60 C in ambience of temperature 20 C to can in third what maximum ressel be heated by this heater in the same ambience for the th 6 00 0 00 V x2 0 00 3 v 0 0 Thermal conductivity in wood depends on the direction of heat flow and

2 A rigid container contains m 3 kg of air The air changes its state from an initial state of p 0 5 MPa and T 75 to its final pressure p 1 2 MPa while it is stirred The heat absorbed is Q 2 195 kJ Assume air to be an ideal gas with c 0 714 kJ kg K Determine the final temperature T2 change in thermal energy AU 2 and work done W 2

A diatomic gas which has initial volume of 10 litre is isothermally compressed to 1 15th of its original volume where initial pressure is 105 Pascal If temperature is 27 C then find the work done by gas a 2 70 10 J b 2 70 10 J d 1 35 x 10 J c 1 35 x 10 J

22 The upper beam in Fig is supported at D and a roller at C which separates the upper and lower eams Determine the values of the reactions at A B C and D Neglect the weight of the beams 4m 400 KN 10 m 60 KN B 4 m 10 m C 190 KN 10 m 4m

potassium permanganate KMnO4 of different concentrations n and n n n molecules pe unit volume with An n n n When they are connected by a tube of small length and cross sectional area S KMnO4 starts to diffuse from the left to the right vessel through the tube Consider the collection of molecules to behave as dilute ideal gases and the difference in thei partial pressure in the two vessels causing the diffusion The speed v of the molecules is limited by the viscous force Bv on each molecule where is a constant Neglecting all terms of the orde An which of the following is are correct ks is the Boltzmann constant 12 A the force causing the molecules to move across the tube is AnkBTS B force balance implies ni vl AnkBT ALLEN CAREER INSTITUTE DANGEROUS AnkaT C total number of molecules going across the tube per sec is 47 S D rate of molecules getting transferred through the tube does not change with time Ans A B C Sol n n n An n RT NA P n P n v Ank T JEE Advanced 2020 Paper 1 Held on Sunday 27 September 2020 F n n kBTS AnkBTS A V Ank TS B ts 122 B n RT NA Force balance Pressure Area Total number of molecules Bv Ank TS n S v Total number of molecules ser n vdt S JEE Advanced 2020 Paper 1

A 5 litre of vessel contains 2 mole of oxygen gas at pressure of 8 atmosphere The average translational kinetic energy of oxygen molecule under this condition is 8 4 x 10 14 J 4 98 x 10 21 J 4 6 x 10 12 J 9 3 10 16 J

A gas undergoes a cyclic process ABCDA as shown in the figure The part ABC of process is semicircular The work done by the gas is B P N m 50 30 A D C 20 V m 1 400 TI 2 2456 I 3 200 T 4 1826 I 60

1 Which of the following has high specific heat A Hg B Fe C Ice D Water 2 The temperature T of two samples of the same substances with masses m and m and tempera tures T and T when added together is A m T m T B m T m T m m C m T m T m m D m T m T

Six moles of an ideal gas performs a cycle shown in figure If the temperature are TA 600 K TB 800 K Tc 2200 K and Tp 1200 K the work done per cycle is 120 kJ Question Type Single Correct Type 230 kJ PA B 3 40 kJ B A D C T

A carnot engine absorbs an amount Q of heat from a reservoir at an absolute temperature T and rejects heat to a sink at a temperature of T The amount of 5 heat rejected is Question Type Single Correct Type 1 Q 6 2 Q 5 3 Q 4

The P V diagram of a system undergoing thermodynamic transformation is shown in figure The work done on the system in going from A B C is 50 J and 20 cal heat is given to the system The change in internal energy between A and C is 14 1 34 J 2 70 3 84 J 4 134 J

540 g of ice at 0 C is mixed with 540 g of water at 80 C The final temperature of the mixture is Given latent heat of fusion of ice 80 cal g and specific heat capacity of water 1 cal g C 0 C 40 C 80 C Less than 0 C

A sample of an ideal gas is taken through the cyclic process abca shown in the figure The scale of the vertical axis is set by pb 8 7 kPa and Pac 4 06 kPa At point a T 204 K a How many moles of gas are in the sample What are b the temperature of the ga at point b c the temperature of the gas at point c and d the net energy added to the gas as heat during the cycle Assume V 1 63 m Vbc 4 82 m Pressure kPa Pac Va b Vic

The work done in an isochoric process is a function of the temperature only You missed this answer Cp Cv for all gases without exception The work done by a gas in an isobaric

A rectangular box of length consisting of two chambers of length 1 2 each separated by a smooth piston lies on a horizontal surface with the piston being movable along its length Each chamber consists of n moles of gas at pressure Po volume Vo and temperature To 127 C Initially the walls of the box are conducting and the piston is pushed slowly such that the temperature virtually remains constant By the time the ratio of volumes of the chambers become 3 1 an amount of heat equal to Q is exchanged with the surroundings On the other hand if walls are insulated and piston alone is conducting the temperature of the gas becomes T in the larger chamber by the time volume ratio becomes 3 1 Let Cp be equal to 2R Read Less Choose the correct options The value of Q is nRT In The value of Q is nRToln 3 The value of Q is 2nRT In Adiabatic exponent 7 of gas is 2

Two substances A and B of equal mass m are heated at uniform rate of 6 cal s under similar conditions A graph between temperature and time is shown in figure Ratio of heat absorbed HA HB by them for complete fusion is a 9 4 c 8 5 Temperature C 88888 100 80 60 40 20 0 1 2 3 4 5 6 7 b 4 9 d 5 8 B COM

A chromatography column with a length of 10 3 cm and inner diameter of 4 61 mm is packed with a stationary phase that occupies 61 0 of the volume If the volume flow rate is 1 13 mL min find the linear flow rate A 17 4 cm min B 15 4 cm min C 14 7 cm min D 15 4 cm min