Heat and Thermodynamics · Physics · NEET
MCQ (Single Correct Answer)
1
Given below are two statements: One is labelled as Assertion $$\mathbf{A}$$ and the other is labelled as Reason $$\mathbf{R}$$.
Assertion A: Houses made of concrete roofs overlaid with foam keep the room hotter during summer.
Reason R: The layer of foam insulation prohibits heat transfer, as it contains air pockets.
In the light of the above statements, choose the correct answer from the options given below.
NEET 2024 (Re-Examination)
2
The equilibrium state of a thermodynamic system is described by
A. Pressure
B. Total heat
C. Temperature
D. Volume
E. Work done
Choose the most appropriate answer from the options given below.
NEET 2024 (Re-Examination)
3
According to the law of equipartition of energy, the number of vibrational modes of a polyatomic gas of constant $$\gamma=\frac{C_p}{C_v}$$ is ($$C_P$$ where $$C_V$$ are the specific heat capacities of the gas at constant pressure and constant volume, respectively):
NEET 2024 (Re-Examination)
4
A thermodynamic system is taken through the cycle $$abcda$$. The work done by the gas along the path $$b c$$ is:
NEET 2024
5
The following graph represents the $$T$$-$$V$$ curves of an ideal gas (where $$T$$ is the temperature and $$V$$ the volume) at three pressures $$P_1, P_2$$ and $$P_3$$ compared with those of Charles's law represented as dotted lines.
Then the correct relation is :
NEET 2024
6
For the given cycle, the work done during isobaric process is:
NEET 2023 Manipur
7
A container of volume $$200 \mathrm{~cm}^3$$ contains 0.2 mole of hydrogen gas and 0.3 mole of argon gas. The pressure of the system at temperature $$200 \mathrm{~K}$$ ($$\mathrm{R}=8.3 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}$$) will be :-
NEET 2023 Manipur
8
The temperature of a gas is $$-50^{\circ} \mathrm{C}$$. To what temperature the gas should be heated so that the rms speed is increased by $$3$$ times?
NEET 2023
9
A Carnot engine has an efficiency of $$50 \%$$ when its source is at a temperature $$327^{\circ} \mathrm{C}$$. The temperature of the sink is :-
NEET 2023
10
An ideal gas follows a process described by the equation $$P{V^2} = C$$ from the initial $$({P_1},\,{V_1},\,{T_1})$$ to final $$({P_2},\,{V_2},\,{T_2})$$ thermodynamic states, where C is a constant. Then
NEET 2022 Phase 2
11
Two rods one made of copper and other made of steel of same length and same cross sectional area are joined together. The thermal conductivity of copper and steel are 385 J s$$-$$1 K$$-$$1 m$$-$$1 and 50 J s$$-$$1 K$$-$$1 m$$-$$1 respectively. The free ends of copper and steel are held at 100$$^\circ$$C and 0$$^\circ$$C respectively. The temperature at the junction is, nearly :
NEET 2022 Phase 2
12
Three vessels of equal capacity have gases at the same temperature and pressure. The first vessel contains helium (monoatomic), the second contains fluorine (diatomic) and the third contains sulfur hexafluoride (polyatomic). The correct statement, among the following is :
NEET 2022 Phase 2
13
An ideal gas undergoes four different processes from the same initial state as shown in the figure below. Those processes are adiabatic, isothermal, isobaric and isochoric. The curve which represents the adiabatic process among 1, 2, 3 and 4 is
NEET 2022 Phase 1
14
The volume occupied by the molecules contained in 4.5 kg water at STP, if the intermolecular forces vanish away is
NEET 2022 Phase 1
15
A cup of coffee cools from 90$$^\circ$$C to 80$$^\circ$$C in t minutes, when the room temperature is 20$$^\circ$$C. The time taken by a similar cup of coffee to cool from 80$$^\circ$$C to 60$$^\circ$$C at a room temperature same at 20$$^\circ$$C is :
NEET 2021
16
Match Column - I and Column - II and choose the correct match from the given choices.
| Column - I | Column - II | ||
|---|---|---|---|
| (A) | Root mean square speed of gas molecules | (P) | $${1 \over 3}nm{\overline v ^2}$$ |
| (B) | Pressure exerted by ideal gas | (Q) | $$\sqrt {{{3RT} \over M}} $$ |
| (C) | Average kinetic energy of a molecule | (R) | $${5 \over 2}RT$$ |
| (D) | Total internal energy of 1 mole of a diatomic gas | (S) | $${3 \over 2}{k_B}T$$ |
NEET 2021
17
The average thermal energy for a mono-atomic gas is : (kB is Boltzmann constant and T absolute temperature)
NEET 2020 Phase 1
18
The mean free path for a gas, with molecular diameter d and number density n can be expressed as :
NEET 2020 Phase 1
19
A cylinder contains hydrogen gas at pressure 249 kPa and temperature 27$$^\circ $$C
Its density is : (R = 8.3 J mol-1 K-1)
Its density is : (R = 8.3 J mol-1 K-1)
NEET 2020 Phase 1
20
The quantities of heat required to raise the temperature of two solid copper spheres of radii r1 and r2 (r1 = 1.5r2) through 1 K are in the ratio :
NEET 2020 Phase 1
21
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 systems is thermally insulated. The stop cock is suddenly opened. The Process is :
NEET 2020 Phase 1
22
In which of the following processes, heat is neither absorbed nor released by a system?
NEET 2019
23
Increase in tempertaure of a gas filled in a container would lead to :
NEET 2019
24
The efficiency of an ideal heat engine working
between the freezing point and boiling point
of water, is
NEET 2018
25
A sample of 0.1 g of water at 100°C and normal
pressure (1.013 × 105
N m–2) requires 54 cal
of heat energy to convert to steam at 100°C.
If the volume of the steam produced is 167.1 cc,
the change in internal energy of the sample, is
NEET 2018
26
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
27
At what temperature will the rms speed of
oxygen molecules become just sufficient for
escaping from the Earth’s atmosphere?
(Given : Mass of oxygen molecule (m) = 2.76 × 10–26 kg, Boltzmann’s constant kB = 1.38 × 10–23 J K–1)
(Given : Mass of oxygen molecule (m) = 2.76 × 10–26 kg, Boltzmann’s constant kB = 1.38 × 10–23 J K–1)
NEET 2018
28
A gas mixture consists of 2 moles of O2 and 4 moles of Ar at temperature T. Neglecting all vibrational modes, the total internal energy of the system is
NEET 2017
29
Thermodynamic processes are indicated in the following diagram.
Match the following
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 | |
NEET 2017
30
A carnot engine having an efficiency of $${1 \over {10}}$$ 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
31
A given sample of an ideal gas occupies a volume V at a pressure P and absolute temperature T. The mass of each molecule of the gas is m. Which of the following gives the density of the gas ?
NEET 2016 Phase 2
32
The temperature inside a refrigerator is t2 oC. The amount of heat delivered to the room for each joule of electrical energy consumed ideally will be
NEET 2016 Phase 2
33
One mole of an ideal monatomic gas undergoes a process described by the equation PV3 = constant. The heat capacity of the gas during this process is
NEET 2016 Phase 2
34
A refrigerator works between 4oC and 30oC. 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 Phase 1
35
The molecules of a given mass of a gas have r.m.s. velocity of 2000 m s$$-$$1 at 27oC and 1.0 $$ \times $$ 105 N m$$-$$2 pressure. When the temperature and pressure of the gas are respectively, 127oC and 0.05 $$ \times $$ 105 N m$$-$$2, the r.m.s. velocity of its molecules in m s$$-$$1 is
NEET 2016 Phase 1
36
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 Phase 1
37
An ideal gas is compressed to half its initial volume by means of several processes. Which of the process results in the maximum work done on the gas ?
AIPMT 2015
38
The coefficient of performance of a refrigerator is 5. If the temperature inside freezer is $$-$$20oC, the temperature of the surroundings to which it rejects heat is
AIPMT 2015
39
Two vessels separately contain two ideal gases A and B at the same temperature, the pressure of A being twice that of B. Under such conditions, the density of A is found to be 1.5 times the density of B. The ratio of molecular weight of A and B is
AIPMT 2015
40
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
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
AIPMT 2015 Cancelled Paper
41
A Carnot 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
AIPMT 2015 Cancelled Paper
42
The ratio of the specific heats $${{{C_p}} \over {{C_v}}} = \gamma $$ in terms of degrees of freedom (n) is given by
AIPMT 2015 Cancelled Paper
43
One mole of an ideal diatomic gas undergoes a transition from A to B along a path AB as shown in the figure.
The change in internal energy of the gas during the transition is
The change in internal energy of the gas during the transition is
AIPMT 2015 Cancelled Paper
44
The mean free path of molecules of a gas, (radius r) is inversely proportional to
AIPMT 2014
45
A thermodynamic system undergoes cyclic process ABCDA as shown in figure. The work done by the system in the cycle is
AIPMT 2014
46
A monatomic gas at a pressure P, having a volume V expands isothermally to a volume 2V and then adiabatically to a volume 16V. The final pressure of the gas is (Take $$\gamma $$ = 5/3)
AIPMT 2014
47
In a vessel, the gas is at pressure P. If the mass of all the molecules is halved and their speed is doubled, then the resultant pressure will be
NEET 2013 (Karnataka)
48
A system is taken from state a to state c by two paths adc and abc as shown in the figure. The internal energy at a is $${U_a} = 10\,J$$. Along the path adc the amount of heat absorbed dQ1 $$=$$ 50 J and the work obtained dW1 $$=$$ 20 J whereas along the path abc the heat absorbed dQ2 = 36 J. The amount of work allong the path abc is
NEET 2013 (Karnataka)
49
Which of the following relations does not give the equation of an adiabatic process, where terms have their usual meaning?
NEET 2013 (Karnataka)
50
Two Carnot engines A and B are operated in series. The engine A receives heat from the source at temperature T1 and rejects the heat to the sink at temperature T. The second engine B receives the heat at temperature T and rejects to its sink at temperature T2. For what values of T the efficiencies of the two engines are equal
NEET 2013 (Karnataka)
51
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?
A $$ \to $$ B $$ \to $$ C $$ \to $$ A, as shown. what is the net work done by the gas?
NEET 2013
52
In the given (V $$-$$ T) diagram, what is the relation between pressure P1 and P2?
NEET 2013
53
During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its temperature. The ratio of $${{{C_p}} \over {{C_p}}}$$ for the gas is
NEET 2013
54
The amount of heat energy required to raise the temperature of 1 g of Helium at NTP, from T1K to T2K is
NEET 2013
55
An ideal gas goes from state A to state B via three different processes as indicated in the P-V diagram.
If Q1, Q2, Q3 indicate the heat absorbed by the gas along the three processes and $$\Delta $$U1, $$\Delta $$U2, $$\Delta $$U3 indicate the change in internal energy along the three processes respectively, then
If Q1, Q2, Q3 indicate the heat absorbed by the gas along the three processes and $$\Delta $$U1, $$\Delta $$U2, $$\Delta $$U3 indicate the change in internal energy along the three processes respectively, then
AIPMT 2012 Mains
56
A thermodynamic system is taken through the cycle ABCD as shown in figure. Heat rejected by the gas during the cycle is
AIPMT 2012 Prelims
57
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 process is
AIPMT 2012 Prelims
58
A mass of diatomic gas $$(\gamma = 1.4)$$ at a pressure of 2 atmospheres is compressed adiabatically so that its temperature rises from 27oC to 927oC. The pressure of the gas in the final state is
AIPMT 2011 Mains
59
When 1 kg of ice at 0oC melts to water at 0oC, the resulting change in its entropy, taking latent heat of ice to be 80 cal/oC, is
AIPMT 2011 Prelims
60
During an isothermal expansion, a confined ideal gas does $$-$$ 150 J of work against its surroundings. This implies that
AIPMT 2011 Prelims
61
A monatomic gas at pressure P1 and volume V1 is compressed adiabatically to $${{1 \over 8}^{th}}$$ of its original volume. What is the final pressure of the gas?
AIPMT 2010 Mains
62
If cp and cv denote the specific heats (per unit mass of an ideal gas of molecular weight M, then
AIPMT 2010 Mains
63
If $$\Delta $$U and $$\Delta $$W represent the increase in internal energy and work done by the system respectively in a thermodynamical process, which of the following is true ?
AIPMT 2010 Prelims
64
In thermodynamic processes which of the following statements is not true ?
AIPMT 2009
65
The internal energy change in a system that has absorbed 2 kcal of heat and done 500 J of work is
AIPMT 2009
66
If Q, E and W denote respectively the heat added, change in internal energy and the work done in a closed cyclic process, then
AIPMT 2008
67
At 10oC the value of the density of a fixed mass of an ideal gas divided by it pressure is x. At 110oC this ratio is
AIPMT 2008
68
An engine has an efficiency of 1/6. When the temperature of sink is reduced by 62oC, its efficiency is doubled. Temperatures of the source is
AIPMT 2007
69
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 ?
AIPMT 2006
70
The molar specific heat at constant pressure of an ideal gas is (7/2) R. The ratio of specific heat at constant pressure to that at constant volume is
AIPMT 2006
71
Which of the following processes is reversible?
AIPMT 2005
72
An ideal gas heat engine operates in Carnot cycle between 227oC and 127oC. It absorbs 6 $$ \times $$ 104 cal of heat at higher temperature. Amount of heat converted to work is
AIPMT 2005
73
One mole of an ideal gas at an initial temperature of T K does 6R joule 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 2004
74
The equation of state for 5 g of oxygen at a pressure P and temperature T, when occupying a volume V, will be
(where R is the gas constant)
(where R is the gas constant)
AIPMT 2004
75
An ideal gas heat engine operates in a Carnot cycle between 227oC and 127oC. It absorbs 6 kcal at the height temperature. The amount of heat (in kcal) converted into work is equal to
AIPMT 2003
76
The efficiency of Carnot engine is 50% and temperature of sink is 500 K. If temperature of source is kept constant and its efficiency raised to 60%, then the required temperature of sink will be
AIPMT 2002
77
A scientist says that the efficiency of his heat engine which work at source temperature 127oC and sink temperature 27oC is 26%, then
AIPMT 2001
78
The (W/Q) of a Carnot engine is 1/6, now the temperature of sink is reduced by 62oC, then this ratio becomes twice, therefore the initial temperature of the sink and source are respectively
AIPMT 2000
79
To find out degree of freedom, the expansion is
AIPMT 2000