Thermodynamics Questions and Answers

A steel rod and a brass rod differ by 12cm in length at all temperatures Coefficient of steel and brass are 12x106C and 18x10 6 Crespectively The length of brass and steel rodsat 0 Crespectively are A 36cm 24cm B 24cm 36cm C 18cm 30cm D 30cm 18cm

3 The molar specific heat capacity of an ideal mono atomic gas during a process represented by equation P T constant is 2 2 5 R 1 3 R 3 3 R 4 2 R

A diatomic gas shown on temperature volume T V diagram as shown Hence TA C V 1 Pressure during ab decreases 2 Pressure during ab increases 3 Temperature increases during bc Juring ca

1 An ideal gas is taken through the cycle A B C A as shown in the figure If the net heat suppliec to the gas in the cycle is 5 J the work done by the gas in the process C A is v m IS ElFor ons 1 5J 2 3 15 J B P 10 N m 2 10 J 4 20 J

Two identical finite bodies of constant volume and of constant heat capacity at consta volume Cr are used to drive a heat engine Their initial temperatures are T and T T maximum amount of work which can be obtained from the system is a C 2 IT T T b C T T c C T T d 0

2 A gas is found to obey the law P V Constant Th initial temperature and volume are T and V If th gas expands to a volume 2V its final temperatur becomes 1 2T 3 2T 2 4 LOIN LO To

Online Mock Test Series for NEET 2020 19 A capacitor of capacitance 1 F is charged to 30 V and the battery is then disconnected If it is connected across a 2 F capacitor the energy lost by the system is 1 300 J 2 450 J 4 150 J 3 100 J 20 A particle is moving along a circular path of radius 10 m with a uniform speed 10 m s What will be the average acceleration when the particle completes half revolution 1 10 It m s 20 2 IL 4 Zero 1 2uF 3 4 F 3 10 m s 21 A capacitor having capacitance 1 F with air is filled with two dielectrics as shown Now capacitance of the system is K 2 2 3 F 4 5 F m s 22 A sonometer wire supports a 4 kg load and vibrates in fundamental mode with a tuning fork of frequency 416 Hz The length of the wire between the bridges is now doubled In order to maintain fundamental mode the load should be changed to 1 2 kg 2 8 kg 3 16 kg 4 4 kg 23 A carnot engine has efficiency becomes F when temperature of sir is decreased by 50 K What was the temperature of the sink 1 375 K 3 300 K 24 The pressure P versus density p of a given mass of an ideal gas is shown at two different temperatures T and T 2 325 K 4 350 K T Then relation between T and T T Efficiency 1 T T 2 T T 3 T T 26 4 All the three are possible 25 Sodium and copper have work functions 2 3 eV and 4 6 eV respectively Then the ratio of their threshold wavelengths is nearest to 1 1 2 2 2 1 4 4 1 3 1 4 In Young s double slit experiment if the intensity at the centre of screen is then intensity at a distance from the central maxima is here B fringe width 1 3 Ala Im A 27 The reading of the ammeter in the given figure will be A 40 3 V Vo 60 R 2u R im R 2u R 60 602 www 4V N 12 e w o Test 4 Code A 2 3 4 1 A 28 A luminous point is moving at speed v towards a spherical mirror along its axis Then the speed at which the image of this point object is moving is given by R Radius of curvature and u object distance 1 V Vo WIN A 2 v V 4 V Vo 2u R R

One mole of He gas undergoes a cyclic process as shown in the graph The part of the graph which shows absorption of heat from the surrounding is PA B 1 AB 3 BC and AB D 200 K T 400 K 2 BC 4 AB BC DA

given figure rige in internal energy in processes A and respectively then P B 2 Q A 1 V Medic 1 AU1 AU2 0 2 Net heat will be rejected by the system in process A B 3 Total work done by the system is positive in the process A B

A carnot engine having an efficiency of 10 is being used as a refrigerator If the work done on the refrigerator is 10 J the amount of heat absorbed from the reservoir at lower temperature is 1 99 1 2 100 J 4 11

146 kJ work is performed in order to compress one kilomole of a gas adiabatically and in this process the temperature of the gas increases by 7 C the gas is R 8 3J mol K 1 1 Diatomic 2 Triatomic 3 A mixture of monoatomic and diatomedicall 4 Monoatomic

met 23 For a heat engine the temperature of the source is 127 C To have 60 efficiency the temperature of the sink is 1 160 C 3 113 C 2 200 C 4 113C

Carbon monoxide is carried around a closed cycle abc in which bc is an isothermal process as shown in the figure The gas absorbs 7000 J of heat as its temperature increases from 300 K to 1000 K in going from a to b The quantity of heat rejected by the gas during the process ca is A 4200 J B 5000 J C D 9000 J 9800 J P P V b V

est 1 Code A One mole of an ideal monoatomic gas undergo process ABC as shown in the indicator diagram H supplied to the gas during the process is P 3P P 1 5P V 3 7P V B V C 4 2V 2 6P V A 5 PV

Q4 On mixing 1 g mole of a monoatomic with 1 g mole of a diatomic gas the specific heat of mixture at constant volume will be a R b 3 2 R c 2R d 5 2R Q5 If the total number of H molecules is double that of the 0 molecules then ratio

If the efficiency of a heat engine working between a source and sink is 40 then the coefficient of performance of refrigerator working between the same source and the sink will be 2 25 4 4 1 1 5 3 0 25

Ans 3 4 Two cylinders A and B of equal capacity are connected to each other via a stop cock A contains an ideal gas at standard temperature and pressure B is completely evacuated The entire system is thermally insulated The stop cock is suddenly opened The process is 1 isobaric 3 adiabatic Ans 3 2 isothermal 4 isochoric

SolveLancer Test One mole of an ideal gas is taken from A to D as shown in the given figure Calculate the change in internal energy SolveLancer Test a 1152 5 J b 4600 J c 1600 J d Zero 2 atm 1 atm P D 300 K B C 400 K T

A system is taken from initial state to final state along two paths For path one heat supplied is Q 50 J and W 20 J What is work done along path 2 if heat supplied in path 2 is Q 36 J 34 J 66 J 106 J

2 If Y K and n are values of Young s modulus bulk modulus and modulus of rigidity of any material respectively Choose the correct relation for these parameters a n c K 3YK 9K Y Yn Nm b Y 9Kn 2n 3K 9K1 N m2 d Y Nm 2 Nm 2

10 nmole of a perfect gas undergoes a cyclic process ABCA see figure consisting of the following processes AB Isothermal expansion at temperature T so that the volume is doubled from V to V 2V and pressure changes from P to P BC Isobaric compression at pressure P to initial volume V CA Isochoric change leading to change of pressure from P2 to P Total workdone in the complete cycle ABCA is a nRT In2 1 b 0 c nRTln 2 d nRT In2 1 PA P P A V V 2V

The specific heats C and C of a diatomic gas A are 29 J mol K and 22 J mol K respectively Another diatomic gas B has the corresponding values as 30 J mol K and 21 J mol K respectively Which among the following is correct 1 A has one vibrational degree of freedom and B has two vibrational degrees of freedom 2 A has one vibrational degree of freedom and B has zero vibrational degree of freedom 3 A and B both have one vibrational degree of freedom 4 A and B both have two vibrational degrees of freedom

Two moles of a monatomic ideal gas is taken through a cyclic process shown on pressure P temperature T diagram in figure Process CA is represented as PT where x a and b ae X Constant If efficiency of given cyclic process is 1 a ln 2 b smallest possible integers then find x P N m 10 4 105 2 x 105 300 K B C T

sli 14 A certain diatomic gas has the same specific heats as an ideal gas but a different equation of state PV R T aT2 a 0 001 K The temper of the gas is raised from T 300 K to T at constant pressure It is found work done on the gas is 70 higher than what would be on an ideal gas Choos correct statement s A T 400K internal energy increases by 250R per mole B T 400 K internal energy increases by 350R per mole C Total heat absorbed in the process is 450R per mole D Total heat absorbed in the process is 520R per mole

A U tube made of heat insulating material is shown in figure One limb is closed by a non conducting cork the temperature is To 300 K a 10 J heat is required to be given by the coil so that the air rises to a temperature T 510 K The thermal expansion of mercury is negligible Then the value of a choose nearest integer value of a Neglect the heat flow through the mercury Take Area of the tube as 0 1 m P 75 cm of Hg atm 25 R and density of mercury PH 13 6 x 10 kg m 23 Insulating massless piston h 10 cm Hg

Thermodynamics processes are indicated in the following diagram 2017 P Match the following Column I Process I C Process I Process III P 9 r 700 K 500 K 300 K V Column II a Adiabatic b Isobaric C Isochoric B A pa q c rd s b pc q a rd s b pc q d rb s a pd qb ras c C D

A gas is compressed isothermally to half its initial volume The same gas is compressed separately through an adiabatic process until its volume is again reduced to half Then Phase 11 2016 4 Compressing the gas isothermally or adiabatically will require the same amount of work which of the case whether compression through isothermal or through adiabatic process requires more work will depend upon the atomicity of the gas Compressing the gas isothermally will require more work to be done B 9 Compressing the gas through adiabatic process will require more work to be

Cp and C are specific heats at constant pressure and constant volume respectively It is observed that Cp Cv a for hydrogen gas Cp C b for nitrogen gas The correct relation between a and b is A a 28b B a 1 14 C a b b D a 14b

A Carnot engine whose sink is at 300 K has an efficiency of 40 By how much should the temperature of source be increased so as to increase its efficiency by 50 of original efficiency 2006 A C 380 K 325 K B 275 K D 250 K

The coefficient of performance of a inside refrigerator is 5 If the temperature freezer is 20 C the temperature of the surroundings to which it rejects heat is A 21 C C 41 C B D Re Test 2015 31 C 11 C

10 A Camot engine having an efficiency of as 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 120171 A C 1 J 99 J B 90 J D 100 J

0 When an ideal gaseous system is taken from state i to state f along path iaf it is found Q 50 cal and w 20 cal Along the path ibf Q 36 cal w along ibf is a 1 14 cal 3 16 cal 2 6 cal 4 66 cal b f

A gas is compressed at a constant pressure of 50N m from a volume of 10m to a volume of 4m Energ of 100 then added to the gas by heating Its internal energy is a Increased by 400 b Increased by 200 c Increased by 100 d Decreased by 200

1 A uniform wheel of 800 mm diameter weighing 6kN rest against a rigid rectangular block of 200 mm height Find the least pull through the center of the wheel required just to turn the wheel over the corner of the block Also find the reaction on the block Take all the surfaces to be smooth

A ring shaped tube contains two ideal gases with equal masses and molar masses M 32 and M 28 The gases are separated by one fixed partition and another movable stopper S which can move freely without friction inside the ring at room temperature The angle a is B 182 170 Dice 192 180 M M S Q h S a

Is this kind of question important for NEET I have never seen such ques in PYQS An ideal diatomic gas undergoes a cyclic process as shown in P V diagram The dotted curves are isothermal The efficiency of the heat engine based on these processes is P 4000 K B 2000 K A 1000 K D 2 13 2 19 C sked by 2295291 aesl id Standard XII Stream NEET Aug 1 2021 at 1 06 PM Add your responses Type Text V

An ideal diatomic gas undergoes a cyclic process as shown in P V diagram The dotted curves are isothermal The efficiency of the heat engine based on these processes is 4000 K B 2000 K A 1000 K D 2 13 C V

A fixed amount of a gas undergoes a thermodynamic process as shown such that heat interaction along path B C A is equal to the work done by the gas along path A B C Then process A B is PA 1 C B Question Type Single Correct Type V can only be isothermal 2 can only be adiabatic 3 can be isothermal or adiabatic

of a body falls 36 C in 10 minutes when placed in a surrounding of constant temperature 20 C What will be the temperature of the body after another 10 min Use Newton s law of cooling The temperature from 52 C to Question Type Single Correct Type 1 28 C 2 20 C 3 32 C A 2180

Given T P curve for three processes If initial and final pressure are same for all processes then work done in process 1 2 and 3 is W W2 W3 respectively Correct order is T Question Type Single Correct Type 1 W W W3 2 W W2 W3 3 W W W3 A W W W

I The SI unit of calorific value is KJ kg II Fuels containing oxygen atoms have high calorific value than those of hydrocarbons III Ideal fuel have high calorific value SolveLancer Test a All are correct b I and II are false c I and III are false d II and III are correct

Which of the processes described below are irreversible a The increase in temprature of an iron rod by hammering it b A gas in a small cantainer at a temprature T is brought in which contact with a big reservoir at a higher temprature T increases the temprature of the gas c A quasi static isothermal expansion of an ideal gas in cylinder fitted with a frictionless piston

Fig 12 6 12 10 Consider a cycle followed by an engine Fig 12 6 1 to 2 is isothermal 2 to 3 is adiabatic 3 to 1 is adiabatic Such a process does not exist because a heat is completely converted to mechanical energy in such a process which is not possible b mechanical energy is completely converted to heat in this process which is not possible c curves representing two adiabatic processes don t intersect d curves representing an adiabatic process and an isothermal process don t intersect

A cylinder containing an ideal gas is in vertical position and has a piston of mass M that is able to move up or down without friction Fig 13 2 If the temperature is increased M Fig 13 2 a both pand V of the gas will change b only p will increase according to Charle s law c V will change but not p nurill W

A one metre long both ends open organ pipe is kept in a gas that has double the density of air at STP Assuming the speed of sound in air at STP is 300 m s the frequency difference between the fundamental and second harmonic of this pipe is Hz

The volume V of a monatomic gas varies with its temperature 7 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 g of water of volume 1 cm at 100 C is converted into steam at same temperature under normal atmospheric pressure 1x 105 Pa The volume of steam formed equals 1671 cm If the specific latent heat of vaporisation of water is 2256 J g the change in internal energy is VA 1 2256 J 3 2089 J NEET 2019 Odisha 2 2423 J 4 167 J

If during an adiabatic process the pressure of mixture of gases is found to be proportional to square of its absolute temperature The ratio of Cp C for mixture of gases is cP 1 2 2 1 5 3 1 67 4 2 1 M linh

5 A certain mass of air initially at 150 kPa 0 13m is compressed in a reversible isothermal process During this process heat transfer to air is 20kJ and the internal energy of air increased by 50kJ Find the final volume of air 6 C

The P V plots for two gases during adiabatic processes are shown in the figure The graphs 1 and 2 should correspond respectively to P 12 2 0 0 1 0 and He He and O 3 O and CO 2 V