# Solved papers for NEET Physics Thermodynamical Processes NEET PYQ-Thermodynamical Processes

### done NEET PYQ-Thermodynamical Processes Total Questions - 39

• question_answer1) If the ratio of specific heat of a gas at constant pressure to that at constant volume is $\gamma ,$ the change in internal energy of a mass of gas when the volume changes from V to 2V at constant pressure P is:                   [AIPMT 1998]

A)
$\frac{R}{(\gamma -1)}$

B)
PV

C)
$\frac{P\,V}{(\gamma -1)}$

D)
$\frac{\gamma \,PV}{(\gamma -1)}$

• question_answer2) We consider a thermodynamic system. If $\Delta U$ represents the increase in its internal energy and W the work done by the system, which of the following statements is true?           [AIPMT 1998]

A)
$\Delta U=-W$ in an adiabatic process

B)
$\Delta U=W$ in an isothermal process

C)
$\Delta U=-W$ in an isothermal process

D)
$\Delta U=W$ in an adiabatic process

• question_answer3) An ideal gas at $27\,{}^\circ C$ is compressed adiabattcally to $\frac{8}{27}$ of its original volume. The rise in temperature is $\left( \gamma =\frac{5}{3} \right)$                                                        [AIPMT 1999]

A)
$475\,{}^\circ C$

B)
$402\,{}^\circ C$

C)
$275\,{}^\circ C$

D)
$375\,{}^\circ C$

• question_answer4) An engine takes heat from a reservoir and converts its 1/6 part into work. By decreasing temperature of sink by $62{}^\circ C,$ its efficiency becomes double. The temperatures of source and sink must be:                          [AIPMT 2000]

A)
$90\,{}^\circ C,\text{ }37\,{}^\circ C$

B)
$99\,{}^\circ C,\text{ }37\,{}^\circ C$

C)
$372\,{}^\circ C,\text{ }37\,{}^\circ C$

D)
$206\,{}^\circ C,\text{ }37\,{}^\circ C$

• question_answer5) The temperatures of source and sink of a heat engine are ${{127}^{o}}C$ and ${{27}^{o}}C$ respectively. An inventor claims its efficiency to be 26% then:                                                                      [AIPMT 2001]

A)
it is impossible

B)
it is possible with high probability

C)
it is possible with low probability

D)
data are insufficient

• question_answer6) The efficiency of Carnot engine is 50% and temperature of sink is 500 K. If the temperature of source is kept constant and its efficiency is to be raised to 60%, then the required temperature of the sink will be:                 [AIPMT 2002]

A)
600 K

B)
500 K

C)
400 K

D)
100 K

• question_answer7) For a black body at temperature $727{}^\circ C,$ its radiating power is 60W and temperature of surrounding is $227{}^\circ C$. If the temperature of the black body is changed to $1227{}^\circ C,$ then its radiating power will be:                                                                                                                                   [AIPMT 2002]

A)
123 W

B)
240 W

C)
304 W

D)
320 W

• question_answer8) An ideal gas heat engine operates in a Carnot cycle between ${{227}^{o}}C$ and ${{127}^{o}}C$. It absorbs 6 kcal at the higher temperature. The amount of heat (in kcal) converted into work is equal to:                     [AIPMT 2003]

A)
1.6

B)
1.2

C)
4.8

D)
3.5

• question_answer9) One mole of an ideal gas at an initial temperature of TK does 6R joules of work adiabatically. If the ratio of specific heats of this gas at constant pressure and at constant volume is 5/3, the final temperature of gas will be:   [AIPMT (S) 2004]

A)
$(T+2.4)\text{ }K$

B)
$(T-2.4)\text{ }K$

C)
$(T+4)\text{ }K$

D)
$(T-4)\text{ }K$

• question_answer10) Which of the following processes is reversible?                                                                     [AIPMT (S) 2005]

A)
Transfer of heat by radiation

B)
Electrical heating of a nichrome wire

C)
Transfer of heat by conduction

D)
Isothermal compression

• question_answer11) An ideal gas heat engine operates in Carnot cycle between $227{}^\circ C$ and $127{}^\circ C$. It absorbs $6\times {{10}^{4}}\,\text{cal}$ of heat at higher temperature. Amount of heat converted to work is:   [AIPMT (S) 2005]

A)
$2.4\times {{10}^{4}}\,cal$

B)
$6\times {{10}^{4}}\,cal$

C)
$1.2\times {{10}^{4}}\,cal$

D)
$4.8\times {{10}^{4}}\,cal$

• question_answer12) A Carnot engine whose sink is at 300K 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?                  [AIPMT (S) 2006]

A)
275 K

B)
325 K

C)
250 K

D)
380 K

• question_answer13) An engine has an efficiency of $\frac{1}{6}$. When the temperature of sink is reduced by $62{}^\circ C,$ its efficiency is doubled.  Temperature of the source is :                                             [AIPMT (S) 2007]

A)
$124{}^\circ C$

B)
$37{}^\circ C$

C)
$62{}^\circ C$

D)
$99{}^\circ C$

• question_answer14) If Q, E and W denote respectively the heat added, change in internal energy and the work done in a closed cycle process, then                                                                                                                          [AIPMPT (S) 2008]

A)
$W=0$

B)
$Q=W=0$

C)
$E=0$

D)
$Q=0$

• question_answer15) A monatomic gas at pressure ${{p}_{1}}$ and ${{V}_{1}}$ is compressed adiabatically to $\frac{1}{8}th$ its original volume. What is the final pressure of the gas?                                              [AIPMT (M) 2010]

A)
$64\text{ }{{p}_{1}}$

B)
${{p}_{1}}$

C)
$16\,{{p}_{1}}$

D)
$32\,{{p}_{1}}$

• question_answer16) A mass of diatomic gas $(y=1.4)$ at a pressure of 2 atm is compressed adiabatically so that its temperature rise from $27{}^\circ C$ to $927\,{}^\circ C$. The pressure of the gas is final state is           [AIPMT (M) 2011]

A)
28 atm

B)
68.7 atm

C)
256 atm

D)
8 atm

• question_answer17) During an isothermal expansion, a confined ideal gas does $-150\text{ }J$ of work against its surroundings. This implies that [AIPMT (S) 2011]

A)
300 J of heat has been added to the gas

B)
no heat is transferred because the process is isothermal

C)
150 J of heat has been added to the gas

D)
150 J of heat has been removed from the gas

• question_answer18)  An ideal gas goes from state A to state B via three different processes as indicated in the p-V diagram. If  ${{Q}_{1}},\,\,{{Q}_{2}},\,\,{{Q}_{3}}$ indicate the   heat absorbed by the gas along the three processes and $\Delta {{U}_{1}},\Delta {{U}_{2}},\Delta {{U}_{3}}$ indicate the change in internal energy along the three processes respectively, then                                                                                                            [AIPMT (M) 2012]

A)
${{Q}_{1}}>{{Q}_{2}}>{{Q}_{3}}$ and $\Delta {{U}_{1}}=\Delta {{U}_{2}}=\Delta {{U}_{3}}$

B)
${{Q}_{3}}>{{Q}_{2}}>{{Q}_{1}}$ and $\Delta {{U}_{1}}=\Delta {{U}_{2}}=\Delta {{U}_{3}}$

C)
${{Q}_{1}}={{Q}_{2}}={{Q}_{3}}$ and $\Delta {{U}_{1}}>\Delta {{U}_{2}}>\Delta {{U}_{3}}$

D)
${{Q}_{3}}>{{Q}_{2}}>{{Q}_{1}}$ and $\Delta {{U}_{1}}>\Delta {{U}_{2}}>\Delta {{U}_{3}}$

• question_answer19)  A thermodynamic system is taken through the cycle ABCD as shown in figure. Heat rejected by the gas during the cycle is              [AIPMT (S) 2012]

A)
$2\,pV$

B)
$4\,pV$

C)
$\frac{1}{2}pV$

D)
$pV$

• question_answer20) One mole of an ideal gas goes from an initial state A to final state B via two processes. It first undergoes isothermal expansion from volume V to 3V and then its volume is reduced from 3V to V at constant pressure. The correct p-V diagram representing the two processes is                      [AIPMT (S) 2012]

A)

B)

C)

D)

• question_answer21)  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?[NEET 2013]

A)
2000 J

B)
1000 J

C)
Zero

D)
 2000 J

• question_answer22) During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its temperature. The ratio of $\frac{{{C}_{p}}}{{{C}_{\upsilon }}}$ for the gas is                                          [NEET 2013]

A)
$\frac{4}{3}$

B)
2

C)
$\frac{5}{3}$

D)
$\frac{3}{2}$

• question_answer23)  In the given (V-T) diagram, what is the relation between pressures ${{p}_{1}}$ and ${{p}_{2}}$?     [NEET 2013]

A)
${{p}_{2}}={{p}_{1}}$         The slope of the graph $\propto \frac{1}{p}$.

B)
${{p}_{2}}>{{p}_{1}}$

C)
${{p}_{2}}<{{p}_{1}}$

D)
Cannot be predicted

• question_answer24) A monoatomic gas at a pressure p, having a volume V expands isothermally to a volume 2 V and then adiabatically to a volume 16 V. The final pressure of the gas is (take $\gamma =\frac{5}{3}$)                        [NEET 2014]

A)
64 p

B)
32 p

C)
$\frac{p}{64}$

D)
16 p

• question_answer25)  A thermodynamic system undergoes cyclic process ABCDA as shown in figure. The work done by the system in the cycle is                                                                                                                                          [NEET 2014]

A)
${{p}_{0}}{{V}_{0}}$

B)
$2{{p}_{0}}{{V}_{0}}$

C)
$\frac{{{p}_{0}}{{V}_{0}}}{2}$

D)
zero

• question_answer26)  Figure below shows two paths that may be taken by a gas to go from a state A to a state C. In process AB, 400 J of heat is added to the system and in process BC, 100 J of heat is added to the system. The heat absorbed by the system in the process AC will be                                                                           [NEET  2015]

A)
380 J

B)
500 J

C)
460 J

D)
300 J

• question_answer27) A Carnot engine, having an efficiency of $\eta =\frac{1}{10}$ as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorded from the reservoir at lower temperature is                            [NEET  2015]

A)
100 J

B)
99 J

C)
90 J

D)
1 J

• question_answer28)  One mole of an ideal diatomic gas undergoes a transition from A to B along a path AB as shown in the figure.                                                                                        [NEET  2015] The change in internal energy of the gas during the transition is

A)
20 kJ

B)
 20 Kj

C)
20 J

D)
 12 kJ

• question_answer29) 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?                                                                                                         [NEET (Re) 2015]

A)

B)
Isobaric

C)
Isochoric

D)
Isothermal

• question_answer30) The coefficient of performance of a refrigerator is 5. If the temperature inside freezer is $-20{}^\circ C,$ the temperature of the surroundings to which it rejects heat is                                   [NEET (Re) 2015]

A)
$31{}^\circ C$

B)
$41{}^\circ C$

C)
$11{}^\circ C$

D)
$21{}^\circ C$

• question_answer31) A refrigerator works between $4{{\,}^{o}}C$ and $30{{\,}^{o}}C$. It is required to remove 600 calories of heat every second in order to keep the temperature of the refrigerated space constant. The power required is: (Take 1 cal = 4.2 Joules)                                                                                                                                                      [NEET - 2016]

A)
2.365 W

B)
23.65 W

C)
236.5 W

D)
2365 W

• question_answer32) 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 :-                                                       [NEET - 2016]

A)
Compressing the gas isothermally will require more work to be done.

B)
Compressing the gas through adiabatic process will require more work to be done.

C)
Compressing the gas isothermally or adiabatically will require the same amount of work.

D)
Which of the case (whether compression through isothermal or through adiabatic process) requires more work will depend upon the atomicity of the gas.

• question_answer33)  Thermodynamic processes are indicated in the following diagram.                  [NEET-2017] Match the following Column-1                     Column-2 P. Process I                    a. Adiabatic Q. Process II                  b. Isobaric R. Process III                  c. Isochoric S. Process IV                  d. Isothermal

A)
$P\to d,\,Q\to b,\,R\to a,\,S\to c$

B)
$P\to a,\,Q\to c,\,R\to d,\,S\to b$

C)
$P\to c,\,Q\to a,\,R\to d,\,S\to b$

D)
$P\to c,\,Q\to d,\,R\to b,\,S\to a$

• question_answer34) A Carnot engine having an efficiency of $\frac{1}{10}$  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                                                                                         [NEET-2017]

A)
100 J

B)
1 J

C)
90 J

D)
99 J

• question_answer35)  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                  [NEET - 2018]

A)
$\frac{1}{3}$

B)
$\frac{2}{3}$

C)
$\frac{2}{5}$

D)
$\frac{2}{7}$

• question_answer36) The efficiency of an ideal heat engine working between the freezing point and boiling point of water, is  [NEET - 2018]

A)
6.25%

B)
20%

C)
26.8%

D)
12.5%

• question_answer37) A sample of 0.1 g of water at $\text{100 }\!\!{}^\circ\!\!\text{ C}$and normal pressure $\text{(1}\text{.013 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{5}}}\text{N}{{\text{m}}^{\text{--2}}}\text{)}$ requires 54 cal of heat energy to convert to steam at$\text{100 }\!\!{}^\circ\!\!\text{ C}$. If the volume of the steam produced is 167.1 cc, the change in internal energy of the sample, is                                                                                                                                                [NEET - 2018]

A)
42.2 J

B)
208.7 J

C)
104.3 J

D)
84.5 J

• question_answer38) In which of the following processes, heat is neither absorbed nor released by a system?             [NEET 2019]

A)
Isobaric

B)
isochoric

C)
Isothermal

D)

• question_answer39) 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:                                                                                                    [NEET 2020]

A)

B)
isochoric

C)
isobaric

D)
isothermal