‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
FUNDAMENTALS OF THERMODYNAMICS
(SNS 204)
MCQ Question Bank
Under the supervision of Dr. Naguib
Page 1 of 31
‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
Table of Contents
1- GENERAL QUESTIONS (41 Q)............................................................................................ 3
2- Basics of Thermodynamics............................................................................................... 8
•
Heat & Temperature (22Q) .......................................................................................... 8
•
Specific Heat & Latent Heat (25Q) ............................................................................. 11
•
Phase Change (24Q) ................................................................................................... 14
•
Heat Transfer ( 22Q ) .................................................................................................. 18
3- First law of Thermodynamics ......................................................................................... 21
•
Types of thermodynamic process & Ideal gases (50 Q ) ............................................ 21
Page 2 of 31
‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
1- GENERAL QUESTIONS (41 Q)
1.Addition of heat at constant pressure to a gas
results in
A.
Raising its temperature
B.
Raising its pressure
C.
Raising its volume
D.
Raising its temperature and doing external work
Answer: Option D
Solution:
Addition of heat at constant pressure to a gas results in
Raising its temperature and doing external work
When you heat a gas, both its vapor pressure and the
volume it occupies increase. The individual gas
particles become more energetic and the temperature
of the gas increases.
2.Which of the following items is not a path
function?
values were plotted out, a linear relationship would be
apparent.
Extrapolating this line to the point where there would
be no pressure yields absolute zero, which is about 273.15 degrees Celsius.
5.Work-done in a free expansion process is
A.
Zero
B.
Minimum
C.
Maximum
D.
Positive
Answer: Option A
No explanation is given for this question.
6.A process, in which the temperature of the working
substance remains constant during its expansion or
compression, is called
A.
Adiabatic process
B.
Isothermal process
Hyperbolic process
A.
Heat
C.
B.
Work
C.
Kinetic energy
D.
Polytropic process
Answer: Option B
No explanation is given for this question
7.A molecule consisting of one atom is known as
D.
Thermal conductivity
Answer: Option D
Solution:
Heat and work are path functions because they depend
on how a system changes from initial to final state,
hence they are state functions. Thermal conductivity is
mainly a function of the motion of the free electrons
therefore property of a material, not a path function.
A.
Mono-atomic
B.
Di-atomic
C.
Tri-atomic
A.
0°C
B.
-273°C
D.
Poly-atomic
Answer: Option A
Solution:
A molecule consisting of one atom is known as Monoatomic
In the gaseous phase at sufficiently high
temperatures, all the chemical elements are
monatomic gases.
8.Total heat of a substance is also known as
C.
273 K
A.
Internal energy
B.
Entropy
C.
Thermal capacity
4.The absolute zero pressure can be attained at a
temperature of
D.
None of these
Answer: Option B
Solution:
Correct Option is (B) The lower the temperature, the
lower the pressure inside of the sphere .If the exact
D.
Enthalpy
Answer: Option D
No explanation is given for this question
Page 3 of 31
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‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
9.Energy can neither be created nor destroyed but
can be converted from one form to other is inferred
from
A.
Zeroth low of thermodynamic
B.
First law of thermodynamics
C.
Second law to thermodynamics
D.
Basic law of thermodynamics
Answer: Option B
10.The amount of heat required to raise the
temperature of 1 kg of water through one Kelvin is
called
D.
Enthalpy
Answer: Option D
Solution:
H = U+PV.
Where, H = Enthalpy,
U = Internal energy,
PV = Product of pressure & volume.
14.The gas constant (R) is equal to the
A.
Sum of two specific heats
B.
Difference of two specific heats
Product of two specific heats
A.
Specific heat at constant volume
C.
B.
Specific heat at constant pressure
C.
kilo-Joule
D.
Ratio of two specific heats
Answer: Option B
15.If a gas is heated against a pressure, keeping the
volume constant, then work done will be equal to
D.
None of these
Answer: Option C
No explanation is given for this question
11.In an isothermal process, the internal energy of
gas molecules
A.
Increases
B.
Decreases
C.
Remain constant
D.
May increase/decrease depending on the
properties of gas
Answer: Option C
No explanation is given for this question
12.The absolute zero pressure will be
A.
+ve
B.
-ve
C.
Zero
D.
Anywhere between zero and infinity
Answer: Option C
16.Characteristic gas constant of a gas is equal to
A.
Cp /Cv
B.
Cv /Cp
C.
Cp - Cv
A.
When molecular momentum of the system
becomes zero
D.
Cp + Cv
Answer: Option C
17.The variables which control the physical
properties of a perfect gas are
B.
At sea level
A.
Pressure exerted by the gas
C.
At the temperature of - 273 K
B.
Volume occupied by the gas
C.
Temperature of the gas
D.
At the center of the earth
Answer: Option A
No explanation is given for this question
13.The sum of internal energy (U) and the product of
pressure and volume (p.v) is known as
A.
Work done
D.
All of these
Answer: Option D
18.A perfect gas at 27°C is heated at constant
pressure till its volume is double. The final
temperature is
B.
Entropy
A.
54°C
C.
Power
B.
327°C
Page 4 of 31
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‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
C.
108°C
D.
654°C
Answer: Option B
23.The door of a running refrigerator inside a room
was left open. Which of the following statements is
correct?
19.In a free expansion process
A.
The room will be cooled to the temperature
inside the refrigerator
A.
Work done is zero
B.
The room will be cooled very slightly
B.
Heat transfer is zero
C.
The room will be gradually warmed up
C.
Both (A) and (B) above
D.
The temperature of the air in room will remain
unaffected
Answer: Option C
24.Which of the following is the extensive property
of a thermodynamic system?
D.
Work done is zero but heat increases
Answer: Option C
20.If a certain amount of dry ice is mixed with same
amount of water at 80°C, the final temperature of
mixture will be
A.
Pressure
A.
80°C
B.
Volume
B.
0°C
C.
Temperature
C.
40°C
D.
Density
Answer: Option B
25.Which of the following is an intensive property of
a thermodynamic system?
D.
20°C
Answer: Option B
21.Work-done during adiabatic expansion is given by
(where p1 v1, T1 = Pressure, volume and
temperature for the initial condition of gas, p2, v2,
T2 = Corresponding values for the final condition of
gas, R = Gas constant, and γ = Ratio of specific heats)
A.
Mass
B.
Temperature
C.
Energy
A.
(p1 v1 - p2, v2)/(γ - 1)
B.
[m R (T1 - T2)] /(γ - 1)
D.
Volume
Answer: Option B
26.First law of thermodynamics deals with
C.
[m R T1/(γ - 1)][1 - (p2, v2 /p1 v1)]
A.
Conservation of heat
D.
All of these
Answer: Option D
22.According to First law of thermodynamics,
B.
Conservation of momentum
C.
Conservation of mass
A.
Total internal energy of a system during a
process remains constant
B.
Total energy of a system remains constant
D.
Conservation of energy
Answer: Option D
27.For reversible adiabatic process, change in
entropy is
C.
Work-done by a system is equal to the heat
transferred by the system
A.
Maximum
B.
Minimum
D.
Internal energy, enthalpy and entropy during a
process remain constant
Answer: Option B
C.
Zero
D.
Negative
Answer: Option C
Page 5 of 31
‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
28.Which of the following is a reversible non-flow
process?
A.
Isochoric process
33.According to kinetic theory of gases, the velocity
of molecules __________ with the increase in
temperature.
B.
Isobaric process
A.
Remains constant
C.
Hyperbolic process
B.
Increases
D.
All of these
Answer: Option D
29.The ratio of specific heat at constant pressure (cp)
and specific heat at constant volume (cv) is
C.
Decreases
A.
Equal to one
A.
Increases
B.
Less than one
B.
Decreases
C.
Greater than one
C.
Remain constant
D.
None of these
Answer: Option B
34.In an isothermal process, the internal energy
D.
None of these
Answer: Option C
30.The amount of heat required to raise the
temperature of the unit mass of gas through one
degree at constant volume, is called
D.
First increases and then decreases
Answer: Option C
35.Properties of substances like pressure,
temperature and density, in thermodynamic
coordinates are
A.
Kilo Joule
A.
Path functions
B.
Specific heat at constant volume
B.
Point functions
C.
Specific heat at constant pressure
C.
Cyclic functions
D.
None of these
Answer: Option B
31.When gas is heated at constant pressure, the heat
supplied is utilized in
D.
Real functions
Answer: Option B
36.Which of the following processes are
thermodynamically reversible?
A.
Increasing the internal energy of gas
A.
Throttling
B.
Doing some external work
B.
Free expansion
C.
Constant volume and constant pressure
C.
Increasing the internal energy of gas and also
for doing some external work
D.
None of the above
Answer: Option C
32.The heat energy stored in the gas and used for
raising the temperature of the gas is known as
A.
External energy
B.
Internal energy
C.
Kinetic energy
D.
Isothermal and adiabatic
Answer: Option D
37.When a gas is heated at constant pressure
A.
Its temperature will increase
B.
Its volume will increase
C.
Both temperature and volume will increase
D.
Neither temperature not volume will increase
Answer: Option C
D.
Molecular energy
Answer: Option B
Page 6 of 31
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‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
Q38: 100 g of water is heated from 30 °C to 50 °C.
Ignoring the slight expansion of the water, the
change in its internal energy is (specific heat of water
is 4184 J kg–1 K–1)
(a) 4.2 kJ
(b) 8.4 kJ
(c) 84 kJ
(d) 2.1 kJ
Solution
ΔQ = msΔT
Here m = 100 g = 100 x10-3 Kg
S = 4184 J kg-1K-1 and ΔT = (50 – 30) = 20 0C
ΔQ = 100 x 10-3 x 4184 x 20 = 8.4 x 103 J
ΔQ = ΔU + ΔW
Change in internal energy
ΔU = ΔQ = 8.4 x 103 J = 8.4 kJ
Answer: (b) 8.4 kJ
Q39: 200 g water is heated from 40° C to 60 °C.
Ignoring the slight expansion of water, the change in
its internal energy is close to (Given specific heat of
water = 4184 J/kg/K)
(a) 167.4 kJ
(b) 8.4 kJ
(c) 4.2 kJ
(d) 16.7 kJ
Solution
For isobaric process, ΔU = Q = msΔT
Here, m = 200 g = 0.2 Kg, s = 4184 J/Kg/K
ΔT = 60 0C – 40 0C = 20 0C
ΔU = (0.2 )(4184)(20) =16736 J = 16.7 kJ
Answer: (d)16.7 kJ
Q40: The work of 146 kJ is performed in order to
compress one-kilo mole of gas adiabatically and in
this process the temperature of the gas increases by
7ºC. The gas is (R = 8.3 J mol–1 K–1)
(a) monoatomic
(b) diatomic
(c) triatomic
(d) a mixture of monoatomic and diatomic
Solution
According to the first law of thermodynamics
ΔQ = ΔU + ΔW
For an adiabatic process, ΔQ = 0
0 = ΔU + ΔW
ΔU = -ΔW
nCvΔT = -ΔW
Cv = -ΔW/nΔT = -[-146 x 103]/[(1 x 103) x 7] = 20.8 Jmol1 -1
K
For diatomic gas, Cv = (5/2)R = (5/2)x8.3 = 20.8 Jmol1 -1
K
Hence, the gas is diatomic
Answer: (b) diatomic
Q41: One mole of a monoatomic gas is heated at a
constant pressure of 1 atmosphere from OK to 100K.
If the gas constant R=8.32 J/mol K, the change in
internal energy of the gas is approximately [1998]
(a) 2.3 J
(b) 46 J
(c) 8.67 × 103J
(d) 1.25 x l03J
Solution
ΔU = nCvdT =1x (3R/2)ΔT
ΔU = (3/2) x (8.3) x (100) = 1.25 x 103 J
Answer: (d) 1.25 x l03J
Page 7 of 31
‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
2- Basics of Thermodynamics
•
Heat & Temperature (22Q)
1. Which of the following is the fastest process of
heat transfer?
a. the specific temperature at which the
substance is in solid state.
b. the energy needed to increase the
temperature of 1 gram of a substance by 1
degree Celsius.
a. conduction
c. the amount of heat conducted in 1 minute.
b. convection
d. the heat needed to increase the temperature
of 1 gallon of water by 1 degree Fahrenheit.
c. radiation
d. insolation
Answer (b).
Answer (c).
5. How will a metal container full of hot water in
vaccum lose heat?
2. 1 gm of ice at 0° C is mixed with 1 gm of steam at
100° C. After thermal equilibrium, the temperature
of the mixture is
a. by conduction
b. by convection
a. 0° C
c. by radiation
b. 50° C
d. will stay hot for ever
c. 80° C
Answer (c).
d. 100° C
Answer (a).
3. Why does the bottom of a lake not freeze in severe
winter even when the surface is all frozen?
6. As a solid undergoes a phase change to a liquid
state, it
a. releases heat while remaining at a constant
temperature.
a. The water has large specific heat
b. absorbs heat while remaining at a constant
temperature.
b. The conductivity of ice is low
c. releases heat as the temperature decreases.
c. The water has large latent heat of fusion
d. absorbs heat as the temperature increases.
d. The temperature of the earth at the bottom
of the lake is high.
Answer (b).
Answer (b).
7. A cup of hot tea on a metal table in a room loses
heat by
a. Conduction
4. Specific heat is -
b. Convection
c. Radiation
Page 8 of 31
‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
d. All the above
Answer (d).
8. What would happen to a hole in a metal sheet
when the sheet is heated?
a. It decreases in size
b. It increases in size
c. No change is seen
d. First increases and then decreases
Answer (b).
9. In which of the following processes of heat transfer
no medium is required?
a. Conduction
b. Convection
c. Radiation
d. All
Answer (c).
10. In which of the following processes is heat
transferred directly from molecule to molecule?
a. conduction
b. convection
c. radiation
d. all of the above
Answer (a).
11. When a solid, liquid, or a gas changes from one
physical state to another, the change is called
c. a phase change
d. sublimation
Answer (c).
12. Compared to warm air, cool air can hold
a. more water vapour
b. less water vapour
c. the same amount of water vapour
d. temperature is unimportant here
Answer (b).
13. The change of state directly from solid to gas is
called
a. evaporation
b. sublimation
c. condensation
d. deposition
Answer (b).
14. Which one among the following statements about
thermal conductivity is correct?
a. Steel > Wood > Water
b. Steel > Water > Wood
c. Water > Steel > Wood
d. Water > Wood > Steel
Answer (b).
15. A hot object loses heat to its surroundings in the
form of heat radiation. The rate of loss of heat
depends on the
a. melting
a. temperature of the object
b. enthalpy
b. temperature of the surroundings
Page 9 of 31
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‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
c. temperature difference between the object
and its surroundings
d. average temperature of the object and its
surroundings
Answer (c).
16. Body A of mass 2 kg and another body B of mass 4
kg and of same material are kept in the same sunshine
for some interval of time. If the rise in temperature is
equal for both the bodies, then which one among the
following in this regard is correct?
a. Heat absorbed by B is double because its mass
is double
b. Heat absorbed by A is double because its
mass is half
c. Heat absorbed by Both A and B is equal
because the quantity of heat absorbed does
not depend upon mass
18. Which one among the following waves are called
waves of heat energy?
a. Radio waves
b. Infrared waves
c. Ultraviolet waves
d. Microwaves
Answer (b).
19. Which one of the following is the mode of heat
transfer in which warm material is transported so as
to displace a cooler material?
a. Conduction only
b. Convection only
c. Radiation
d. Both conduction and convection
Answer (b).
d. Heat absorbed by B is four times than the
heat absorbed by A because the quantity of
heat absorbed is proportional to square of the
mass
Answer (a).
20. Which one among the following denotes the
smallest temperature?
a. 1° on the Celsius scale
17. A glass of water does not turn into ice as it reaches
0° C. It is because
a. water does not solidify at 0° C
b. a certain amount of heat must be supplied to
the glass of water so as to solidify
c. a certain amount of heat must be taken out
from the glass of water so as to solidify
d. water solidifies at 0° K only
Answer (c).
b. 1° on the Kelvin scale
c. 1° on the Fahrenheit scale
d. 1° on the Reaumur scale
Answer (b).
21. How many degrees of freedom are there in a
monatomic gas?
a. 1
b. 2
c. 3
d. 0
Answer: c
Explanation: A monatomic gas has 3 translational
degrees of freedom.
Page 10 of 31
‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
22. How many degrees of freedom are there in a
diatomic gas?
a) 2
b) 5
c) 3
d) 1
Answer: b
Explanation: A diatomic gas has 3 translational
degrees of freedom and 2 rotational degrees of
freedom. Thus, the total number of degrees of
freedom is 5.
• Specific Heat & Latent Heat (25Q)
3. Specific heat capacity depends on the mass of
the substance. True or False?
a) True
b) False
Answer: b
Explanation: Specific heat capacity is defined as the
heat capacity per unit mass for a substance. s =
ΔQ/mΔT. So, no matter what mass of a substance
we take ‘s’ will be equal to (ΔQ/ΔT) divided by that
mass, which means ‘s’ doesn’t depend on the mass.
1. If we supply equal amounts of heat to equal
masses of two different substances, the rise in
temperature will be the same for both. True or
False?
4. CP > CV always. True or False?
a) True
b) False
Answer: a
Explanation: When heat is added at constant
pressure the heat is used to increase temperature
and increase volume or we can say does work. But
when heat is added at constant volume the heat
only increases temperature and volume remains
the same (work = 0). So For the same rise in
temperature at constant pressure we have to
provide more heat.
Answer: b
Explanation: Each body has a heat capacity which
indicates the amount of heat it requires to raise its
temperature by 1°C. Different substances require
different amounts of heat for the same rise in
temperature.
2. Why is water used in automobiles as a coolant?
a) It is not toxic for the environment
b) It has a high specific heat capacity
c) It has a high lubricating property which in turn
keeps the engine cool by reducing friction
d) It is available in abundance
a) True
b) False
5. What is the relation between molar heat
capacities of the two processes given in the diagram
below? Assume process acb has a heat capacity of
C1 and process adb has a heat capacity of C2.
Answer: b
Explanation: Water has a high specific heat capacity
because of which it can absorb large amounts of
heat before increasing its temperature. Hence, it is
used as a coolant.
Page 11 of 31
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Faculty of Navigation Science and Space Technology
a) C1 > C2
b) C2 > C1
c) C1 = C2
d) C1 = C1/ Area inside curve
Answer: b
Explanation: As the start and end points are the
same for both processes, the temperature rise will
be the same. The work done in process adb is more
than that done in process acb. Therefore heat
supplied will be less in process acb, so C2 > C1.
8. The internal energy change in a system that has
absorbed 2kcal of heat and done 500 J of work is?
a) 6400 J
b) 5400 J
c) 7900 J
d) 8900 J
Answer: c
Explanation: As Q=∆U+W
∆U=Q-W=2×4.2×1000-500
∆U=8400-500=7900 J.
6. A closed container contains 0.6m3 of neon gas at
200K temperature and 1.3*105Pa. Find the rise in
temperature when 8360 J of heat is supplied to it.
The molar heat capacity of neon at constant volume
is 3.2calK-1mol-1. Assume the container doesn’t
expand on heating.
a) 13.3K
b) 15.8K
c) 13.9K
d) 15K
9. 110 J of heat is added to a gaseous system, whose
internal energy increases by 40 J. Then the amount of
external work done is?
a) 150 J
b) 70 J
c) 110 J
d) 40 J
Answer: a
Explanation: no. of moles of neon gas = pV/RT
= (1.3*105*0.6) / (8.31*200)
= 46.9 moles ≅ 47 moles
ΔQ = nCVΔT ΔT = ΔQ/nCV
= (8360/4.18) / (47*3.2)
= 13.3K.
10. The molar specific heat constant pressure of an
ideal gas is 7R/2. The ratio of specific heat at constant
pressure to that at constant volume is?
a) 9/7
b) 8/7
c) 7/5
d) 5/7
7. CV of a gas is 8 calK-1mol-1. Find CP/CV. Assume R =
2 calK-1mol-1.
a) 1.4
b) 1.33
c) 1.25
d) 1.8
Answer: c
Explanation: CP = CV + R = 8 + 2
= 10 calK-1mol-1.
CP/CV= 10 / 8 = 1.25.
Answer: b
Explanation: ∆Q=+110 J, ∆U=+4J
∆W=∆Q-∆U=110-40=70J.
Answer: c
Explanation: Cp=7R/2
CV=CP-R=7R/2-R=5R/2
r=Cp/Cv = (7R/2)/(5R/2)=7/5.
11. The change internal energy in a cyclic process is
___________
a) Zero
b) Infinity
c) Constant
d) Unity
Answer: a
Explanation: The change in internal energy in a cyclic
Page 12 of 31
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Faculty of Navigation Science and Space Technology
process is zero because the system returns to its initial
state.
14. It is possible that the temperature of the body
changes even without giving heat to it or taking heat
from it.
a) True
b) False
Answer: a
Explanation: During an adiabatic compression,
temperature increases and an adiabatic expansion,
temperature decreases, although no heat is given to
or taken from the system in these changes.
15. The mechanical energy can be completely
converted into heat energy but the whole of the heat
energy cannot be converted into mechanical energy.
a) True
b) False
Answer: a
Explanation: The whole of mechanical energy can be
absorbed by the molecules of the system in the form
of their kinetic energy. This kinetic energy gets
converted into heat. But the whole of the heat energy
cannot be converted into work as a part of it is always
retained by the system as its internal energy.
16. Which statement is incorrect?
a) All reversible cycles have the same efficiency
b) Reversible cycle has more efficiency than an
irreversible one
c) Carnot cycle is a reversible one
d) Carnot cycle has the maximum efficiency of the
cycles
Answer: a
Explanation: Work done per cycle = Area of the loop
representing the cycle
As different reversible cycles may have different loop
areas, their efficiencies will also be different.
17. The latent heat of vaporisation of water is 2,240 J.
If the work done in the process of vaporisation of 1g is
168 J, then the increase in internal energy is?
a) 2408 J
b) 2240 J
c) 2072 J
d) 1904 J
Answer: c
Explanation: From the first law of thermodynamics,
dQ = mL = dU + dW
dU = m L – dW = 1×2240-168
dU = 2072 J.
18. If the amount of heat given to a system is 35 J and
the amount of work done by the system is -15J and
the amount of work done by the system is -15J, then
the change in the internal energy of the system is?
a) -50J
b) 20J
c) 30
d) 50J
Answer: d
Explanation: ∆Q=∆U+∆W
35=∆U+15
∆U=35+15=50J.
19. Assertion: Reversible systems are difficult to find
in the real world.
Reason: Most process is dissipative in nature.
a) Both assertion and reason are true and the reason
is the correct explanation of the assertion
b) Both assertion and reason are true but the reason
is not a correct explanation of the assertion
c) Assertion is true but the reason is false
d) Both assertion and reason are false
Answer: a
Explanation: Both the assertion and reason are true.
The energy consumed is doing work against
dissipative forces cannot be recovered.
20. During adiabatic compression of a gas, its
temperature ___________
a) Falls
b) Remains constant
c) Rises
d) Becomes zero
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Answer: c
Explanation: The work done on the gas during the
adiabatic process increases its internal energy and
hence its temperature rises.
21. A quantity of heat required to change the unit
mass of a solid substance, from solid state to liquid
state, while the temperature remains constant, is
known as ___________
a) Latent heat
b) Sublimation
c) Hoar frost
d) Latent heat of fusion
Answer: d
Explanation: The amount of heat required to change
the state of the unit mass of a substance from solid at
its melting point is called latent heat of fusion.
22. A constant pressure air thermometer gave a
reading of 47.5 units of volume, when immersed in
ice-cold water, and 67 units in a boiling liquid. What is
the boiling point of the liquid?
a) 100°C
b) 112°C
c) 125°C
d) 135°C
Answer: b
Explanation: From Charles’s law,
V1/T1 = V2/T2
47.5/(0+273)=67/T2
T2=(67×273)/47.5=385K
T2=112°C.
23. 50g of ice at 0°C is mixed with 50g of water at
80°C, what will be the final temperature of a mixture?
(Lwater=80 Cal/g)
a) 0°C
b) 40°C
c) 60°C
d) 4°C
Answer: a
Explanation: Heat required to melt 50g ice = mL =
50×80=4000cal
Heat given out by water in cooling from 80°C to 0 =
mc∆T=50×1×80=4000cal
Heat given by water is just sufficient to melt the
whole ice. So the final temperature is 0°C.
24. 80g of water at 30°C is poured on a large block of
ice which is at 0°C. The mass of ice that melts is
___________ (Lwater=80 Cal/g)
a) 30g
b) 80g
c) 150g
d) 1600g
Answer: a
Explanation: Heat used in melting m gram of ice =
Heat lost by 80g water
mL=80×1×30
m=(80×1×30)/80=30g.
25. A constant volume gas thermometer using helium
records a pressure of 20.0kPa at the triple point of
water and pressure of 14.3 kPa at the temperature of
‘dry ice’. What is the temperature of dry ice?
a) 19.530K
b) 1.9530K
c) 195.30K
d) 1953.0K
Answer: c
Explanation: Temperature of dry ice,
T=P/Ptr ×Ttr=(14.3×273.16)/20
Temperature = 195.30K.
• Phase Change (24Q)
1. What happens in sublimation?
a) Solid vaporizes in liquid phase
b) A liquid vaporizes in gas phase
c) A gas solidifies
d) A solid vaporizes in gas phase without going in
Page 14 of 31
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liquid phase
Answer: d
Explanation: In sublimation, a solid vaporizes in gas
phase without going in liquid phase.
2. What happens in desublimation?
a) Solid vaporizes in liquid phase
b) A liquid vaporizes in gas phase
c) A gas solidifies without changing to liquid
d) A solid vaporizes in gas phase without going in
liquid phase
Answer: c
Explanation: In desublimation, a gas solidifies in solid
phase without going in liquid phase.
c) zero
d) none of the mentioned
Answer: a
Explanation: When temperature of water increase
from zero degree Celsius to the approximately 4
degree Celsius it's molar volume decrease ,this implies
that density of water increase. That is the why slop of
fusion curve of water have negative slop
6. The temperature at which a liquid boils is very
sensitive to pressure but the temperature at which a
solid melts is not such a strong function of pressure.
a) true
b) false
Answer: a
Explanation: The slope of the fusion curve is small.
3. Which of the following curves meet at triple point?
a) fusion curve and vaporization curve
b) fusion curve and sublimation curve
c) vaporization curve and sublimation curve
d) fusion curve and vaporization curve and
sublimation curve
7. In this figure, what does O denote?
Answer: d
Explanation: At triple point, all these three curves
meet.
4. The slopes of sublimation and vaporization curves
for all substances are
a) negative
b) positive
c) zero
d) none of the mentioned
Answer: b
Explanation: This is true for all substances.
5. The slope of the fusion curve for water is
a) negative
b) positive
a) Melting point
b) Boiling point
c) Triple point
d) Vaporization point
Answer: c
Explanation: This graph illustrates the pressuretemperature diagram for a one-component phase
diagram of the H2O system. The point O is marked as
the triple point, which is the point at which three
phases exist at the same time.
Page 15 of 31
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Faculty of Navigation Science and Space Technology
8- Answer the following MCQ questions using the
following figure
b)2,4
answer: b) 2,4
• Which set of segments represents periods
of kinetic energy?
a)1,3,5
b)2,4
answer: a)1,3,5
9 .Based on this phase diagram, which state is the
most dense?
•
Which segment represents the solid
phase ?
a)1
b)2
c)3
d)4
answer: a) 1
• Which segment represents melting? ?
a)1
b)3
c)4
d)2
answer: d) 2
• Which segments have a liquid and gas
present at the same time?
a)2
b)3
c)4
d)5
answer: c) 4
• Which set of segments represents phase
changes?
a)1,3,5
b)2,4
answer: b) 2,4
• Which set of segments represents periods
of potential energy?
a)gas
b)solid
c)liquid
d)solid and liquid have equal densities
answer: c)liquid
a)1,3,5
Page 16 of 31
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10-Answer the following mcq using the following
figure
a) sublimation
b) vaporization
c) melting
d) boiling
answer: b) vaporization
•
What is point A?
a) triple point
b) critical point
c) equilibrium point
d) normal melting point
answer: a) triple point
•
What is point B?
a) triple point
b) critical point
c) equilibrium point
d) normal melting point
answer: b) critical point
• What state of matter is X?
a) solid
b) liquid
c) gas
d) supercritical fluid
answer: a) solid
•
•
What state of matter is Y?
a) solid
b) liquid
c) gas
d) supercritical fluid
answer: b) liquid
What change occurs from F to E?
a) sublimation
b) deposition
c)melting
d)condensation
answer: b) deposition
•
What change occurs from E to C?
a) sublimation
b) deposition
c) melting
d) boiling
answer: c) melting
•
•
Above the temperature of point B, this
substance exists as a.____________
a) solid
b) liquid
c) gas
d) supercritical fluid
answer: d) supercritical fluid
•
Below the temperature of point B, this
substance can exist as a.____________
a) solid only
b) liquid only
c) gas only
d) either a solid, liquid or gas
answer: d) either a solid, liquid or gas
• At 0.10 atm, what phase(s) can exist?
a) solid, liquid or gas
b) liquid or gas
c) solid only
d) gas only
answer: d) gas only
What change occurs from C to D?
Page 17 of 31
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Faculty of Navigation Science and Space Technology
• Heat Transfer ( 22Q )
1. The magnitude of mechanical work is the
a) product of the force and distance travelled
perpendicular to the force
b) product of the force and distance travelled parallel
to the force
c) sum of the force and distance travelled
perpendicular to the force
d) sum of the force and distance travelled parallel to
the force
Answer: b
Explanation: The work is done by a force as it acts
upon a body moving in the direction of the force.
2. Work done by a system is taken to be
a) positive
b) negative
c) zero
d) varies according to situation
Answer: a
Explanation: In thermodynamics, work done by a
system is take to be positive.
3. Work done on a system is taken to be
a) positive
b) negative
c) zero
d) varies according to situation
Answer: b
Explanation: In thermodynamics, work done on a
system is take to be negative.
4. Work is a
a) point function
b) path function
c) depends on the state
d) none of the mentioned
Answer: b
Explanation: Amount of work done depends on the
path the system follows.
5. Thermodynamic properties are
a) point function
b) path function
c) depends on the state
d) none of the mentioned
Answer: a
Explanation: For a given state there is a definite value
for each property.
6. In the equation dV=(1/p)dW, (1/p) is known as
a) volume factor
b) pressure factor
c) differential factor
d) integration factor
Answer: d
Explanation: Used to convert inexact differential dW
into exact differential dV.
7. Constant pressure process is also known as
a) isopiestic process
b) isobaric process
c) all of the mentioned
d) none of the mentioned
Answer: c
Explanation: Isobaric and isopiestic means pressure
being constant.
8. Work done in a quasi-static process
a) depends on the path followed
b) independent of the path followed
c) depends only on the initial and final states
d) none of the mentioned
View Answer
Answer: a
Explanation: This is because work done is a path
function.
9. The transfer of heat between two bodies in direct
contact is called
a) radiation
b) convection
c) conduction
d) none of the mentioned
Page 18 of 31
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Answer: c
Explanation: This is the definition of conduction.
Answer: a
Explanation: c=Q/(m*Δt).
10. Heat flow into a system is taken to be ____, and
heat flow out of the system is taken as ____
a) positive, positive
b) negative, negative
c) negative, positive
d) positive, negative
View Answer
14. Heat and work are
a) path functions
b) inexact differentials
c) depend upon the path followed
d) all of the mentioned
View Answer
Answer: d
Explanation: The direction of heat transfer is taken
from the high temperature system to the low
temperature system.
11. The transfer of heat between a wall and a fluid
system in motion is called
a) radiation
b) convection
c) conduction
d) none of the mentioned
View Answer
Answer: b
Explanation: This is the definition of convection.
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12. For solids and liquids, specific heat
a) depends on the process
b) is independent of the process
c) may or may not depend on the process
d) none of the mentioned
View Answer
Answer: b
Explanation: It is the property of specific heat.
13. The specific heat of the substance is defined as the
amount of heat required to raise a unit mass of the
substance through a unit rise in temperature.
a) true
b) false
View Answer
Answer: d
Explanation: It is an important point to remember
regarding heat and work transfer.
15. Latent heat is taken at
a) constant temperature
b) constant pressure
c) both of the mentioned
d) none of the mentioned
View Answer
Answer: c
Explanation: The latent heat is heat transfer required
to cause a phase change in a unit mass of substance at
a constant pressure and temperature.
16. Which of the following is true?
a) latent heat of fusion is not much affected by
pressure
b) latent heat of vaporization is highly sensitive to
pressure
c) both of the mentioned
d) none of the mentioned
View Answer
Answer: c
Explanation: It is a general fact about latent heat.
17. Heat transfer and work transfer are
a) boundary phenomena
b) energy interactions
c) energy in the transit
d) all of the mentioned
View Answer
Page 19 of 31
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Answer: d
Explanation: It is an important point to remember
regarding heat and work transfer.
Answer: b
Explanation: Forced, natural and mixed convection.
18. The literature of heat transfer generally recognizes
distinct modes of heat transfer. How many modes are
there?
a) One
b) Two
c) Three
d) Four
View Answer
21. A radiator in a domestic heating system operates
at a surface temperature of 60 degree Celsius.
Calculate the heat flux at the surface of the radiator if
it behaves as a black body
a) 697.2 W/m2
b) 786.9 W/m2
c) 324.7 W/m2
d) 592.1 W/m2
View Answer
Answer: c
Explanation: There are three modes of heat transfer
i.e. radiation, convection and conduction.
Answer: a
Explanation: As, q = Q/A = 5.67 * 10-8 (273+60)4 =
697.2.
19. Consider system A at uniform temperature t and
system B at another uniform temperature T (t > T). Let
the two systems be brought into contact and be
thermally insulated from their surroundings but not
from each other. Energy will flow from system A to
system B because of
22. Which of the following is an example of forced
convection?
a) Chilling effect of cold wind on a warm body
b) Flow of water in condenser tubes
c) Cooling of billets in the atmosphere
d) Heat exchange on cold and warm pipes
View Answer
Answer: b
Explanation: In forced convection, the flow of fluid is
caused by a pump, fan or by atmospheric winds.
a) Temperature difference
b) Energy difference
c) Mass difference
d) Volumetric difference
View Answer
Answer: a
Explanation: Greater the temperature imbalance the
higher would be the rate of energy transfer.
20. How many types of convection process are there?
a) One
b) Three
c) Four
d) Two
View Answer
Page 20 of 31
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3- First law of Thermodynamics
• Types of thermodynamic process
& Ideal gases (50 Q )
Multiple choice questions with one or more answers
Question 1
It is known that curves A, B, C are Isobaric,
Isothermal, Adiabatic process then when one is
correct
Solution
(a) A - Adiabatic, B - Isothermal,, C - Isobaric
(b) A- Isothermal,, B - Adiabatic, C - Isobaric
(c) A - Isobaric, B - Isothermal C - Adiabatic
(d) None of these
Solution
Isobaric Pressure is constant
so Curve C is Isobaric
Adiabatic slope is more steep the Isothermal
So Adiabatic - A
And Isothermal - B
so (a) is correct
𝑃𝑉 = 𝐾𝑇
𝑃𝑑𝑉 = 𝐾𝑑𝑇
𝑑𝑉 𝑘
=
𝑑𝑇 𝑃
𝑑𝑉
𝐾
=
𝑉𝑑𝑇 𝑃𝑉
Now as PV = KT
𝑑𝑉
𝐾
1
=
=
𝑉𝑑𝑇 𝐾𝑇 𝑇
𝑑𝑉
1
or 𝛿 =
=
𝑉𝑑𝑇 𝑇
So D is Correct
Question 3
An ideal gas taken round the cycle ABCA as shown in
PV diagram
Question 2
Which of the following graph correctly represent the
variation
𝑑𝑉
𝛿=
𝑉𝑑𝑇
for an ideal gas at constant pressure
The work done during the cycle,
a. PV
b. PV/2
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c. 2PV
d. PV/3
Solution
Solution
Work done is area of the closed loop
= 1 / 2 x V x P = PV / 2
So b is correct
Question 4
Consider the following statements
(Assertion) The internal energy of an ideal gas does
not change during an Isothermal process
(Reason) The decrease in the volume of the gas is
compensated by a corresponding increase in pressure
when its temperature is constant in accordance with
Boyle law
From energy Conservation
1
Δ𝑈 = 𝑛𝑀𝑉 2 where n = moles of gas
2
𝑛𝑅Δ𝑇
now Δ𝑈 =
𝛾−1
1
𝑛𝑅Δ𝑇
So 𝑛𝑀𝑉 2 =
2
𝛾−1
2𝑅Δ𝑇
𝑉2 =
𝑀(𝛾 − 1)
2𝑅Δ𝑇 1/2
𝑉=[
]
𝑀(𝛾 − 1)
Question 6
Match the column
a. Both A & R are true and R is correct Explanation of
A
b. Both A & R are true and R is not correct Explanation
of A
c. A is true R is false
d. A is false but R is true
Solution
(a)
Question 5
A thermally insulated vessel containing an gas when
molar mass is M and Ratio of specific heat Cp / Cv = γ
move with a velocity V.The gas temperature increase
by ΔT due to sudden stoppage of vessel. Find the
value of V in terms of ΔT, M, γ
2𝑅Δ𝑇
1/2
2𝑅Δ𝑇
1/2
a. 𝑉 = [𝑀(𝛾−1)]
b. 𝑉 = [𝑀(𝛾+1)]
c. 𝑉 = [
2𝑅Δ𝑇
1/2
]
𝑀√(𝛾−1)
d. 𝑉 = [
2𝑅Δ𝑇
1/2
]
𝑀√(𝛾+1)
a. a-> q, b -> p, c-> r
b. a-> p, b -> q, c-> r
c. a-> r, b -> q, c-> p
d. a-> p, b -> r, c-> q
Solution
a - AB
b - AC
c - BC
Question 7
An ideal gas is taken through a cyclic thermodynamics
process through four steps.
The amount of heat involved in the steps are Q1 =
5960 J,Q2 = - 5600 J,Q3= -3000 J,Q4 = -3600 J
respectively. The corresponding quantities of Internal
energy changes are ΔU1 = 3.760 J ,ΔU2 = - 4800 J,ΔU3 =
-1800 J,ΔU4 = ?
find the value ΔU4 & net work done
Page 22 of 31
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a. 2930 J, 960 J
b. 2830 J, 900 J
C. 2930 J, -960 J
d. -2930 J, 960 J
a. 3/5
b. 4/3
c. 5/3
d. 3/2
Solution
Solution
since in cycle process total internal change is zero.
ΔU1+ΔU2+ΔU3+ΔU4=0
P2= k T5
P2 =k(PV/nR)5
P2 = k'P5V5 where k'=k/(nR)5 which is a constant
P3V5 = constant
PV5/3 = constant
so Cp / Cv = 5/3
Question 10
One mole of ideal gas having adiabatic coefficient γ1 is
mixed with 1 one mole of an ideal gas have adiabatic
coefficient γ2
Find the γ of the mixture
3670−4800−1800+ΔU4=0
ΔU4=2930
Now in Cycle
ΔW=ΔQ
= 5960 - 5600 - 3000 + 3600 = 960 J.
Hence answer is a
Question 8
An ideal gas who ratio of specific heat Cp / Cv = γ is
Expanded according to the law P = av2
when a is constant. The ratio of final volume to Initial
value is n .find the ΔU.Initial volume is V0
a. aV03 (n3-1) / γ-1
b. aV02 (n2 - 1) / γ-1
c. aV03 (n3 + 1) /γ+1
d. aV02 (n2 + 1) /γ-1
Solution
ΔU = nCvΔT
= (nR / γ-1)(T2-T1)
= P2V2 - P1V1 / γ-1
Now P1 = aV12
P2 = aV22
Now V1=V0
V2/ V1 = n
So V2=nV0
So
P1 = aV02
P2 = an2V02
Substituting these values
ΔU =aV03 (n3-1) / γ-1
Question 9
During an adiabatic process the square of the
pressure of a gas is proportional to the fifth power of
its absolute temperature. The ratio of specific heat
Cp / Cv for that gas is
a.
b.
C.
(𝟐𝜸𝟏 𝜸𝟐 −𝜸𝟏 −𝜸𝟐 )
(𝜸𝟏 +𝜸𝟐 −𝟐)
(𝟐𝜸𝟏 𝜸𝟐 −𝜸𝟏 −𝜸𝟐 )
(𝜸𝟏 +𝜸𝟐 +𝟐)
(𝟐𝜸𝟏 𝜸𝟐 +𝜸𝟏 −𝜸𝟐 )
(𝜸𝟏 +𝜸𝟐 −𝟐)
d. None of these
Solution
(1+1) CvdT = [1 x R /(γ1-1)] dT + [1x R / (γ2-1)dT]
Cv = (R / 2) [(γ1 + γ2 - 2)/(γ1-1)(γ2-1)]
Cp= Cv + R
= R [(γ1 + γ2 - 2 + 2γ1 γ2 -2γ1 - 2γ2 + 2) / 2 (γ1 -1) (γ2 -1)]
= R (2γ1γ1 -γ1 - γ2 ) / 2 ((γ1-1) (γ2-1)
so
γ= (2γ1γ1 -γ1 - γ2 ) /(γ1 + γ2 - 2)
Question 11
We have a process defined as 𝑃𝑉 𝑛 = constant and
we have an adiabatic process defined by 𝑃𝑉 𝛾 =
Constant and so thermal process defined as 𝑃𝑉 =
𝐶onstant find the Ratio of Bulk modules of Polytropic, adiabatic, isothermal process
a. 𝑛: 𝛾: 1
b. 1: 𝑛: 𝛾
c. 𝑛2 : 𝛾 2 : 1
d. 1: 𝑛2 : 𝛾 2
Solution
We know that
Page 23 of 31
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𝐵 = −𝑉𝑑𝑃/𝑑𝑉
constantPV n =
differentiating
𝑉 𝑛 𝑑𝑃 + 𝑛𝑃𝑉 𝑛−1 𝑑𝑉 = 0
or −𝑉 d 𝑃/𝑑𝑉 = 𝑛𝑃
Similarly for PV Y = Constant
B = yP
And for PV = Constant
B=P
So Ans n:y:1
Question 12
Find the wok done in the cyclic process as shown in
figure
Let Q1, Q2 , Q2 heat given to the system in processes A,
B, C respectively
consider two statements
a, Q1 > Q2 > Q3
b, WA > WB > WC
1, Both A & B are Correct
2, Both A & B are wrong
3. A is Correct Only
4. B is Correct Only.
Solution
𝑛2 𝑃𝑉
2
𝑛2 𝑃𝑉
b. 8
𝑛2 𝑃𝑉
C. 16
a.
Now we know that
ΔU = Q - W
for three process
ΔU = Q1 - WA Q1 = ΔU + WA
ΔU = Q2 - WB Q2 = ΔU +WB
ΔU = Q3 - WC Q3 = ΔU + WC
Now Work done is given by Area under curve so WA >
WB > W C
So
Q1 > Q2 > Q 3
So A & B both are correct
d. none of these
Solution
W.D. = (1/2)PV +(3/2)PV +(5/2)PV + ......(2n-1)PV/2
= (PV/2) [1 + 3 + 5 + (2n-1)]
= (PV/2) [1 + 3 + 5 + (2n-1)]
= (PV/2)(n/2) [2 + (n-1)2]
= (PV/2) x (n/2)x(2n)
= n2PV/2
Question 13
Question 14
Match the Column
Column A
a. Isothermal process
b. Adiabatic Process
c. Isobaric process
d. Isochoric process
Column B
x. ΔU = ΔQ
y. ΔU = ΔQ - ΔW
z. ΔU = -ΔW
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‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
w. ΔQ = ΔW
placed on table
Box A contain one mole of gas m where (Cv=5R/2) at
Temperature T0
Box B contains one mole of gas n where (Cv=3R/2) at
temperature (7/3) T0
The boxes are then put into thermal contact with each
other and heat flows between until the gases reach a
common final temperature Tf
Which of the following relation is correct?
a. 2Tf-3T0=0
b. 2Tf-7T0=0
c. 2Tf-5T0=0
d. Tf-3T0=0
a, a -> x, b-> y, c->z, d->w
b, a->w, b->z, c->x, d->y
c, a->y, b->x, c->z, d->w
d, a->z,b->w,c->y,d->x
Solution
Isothermal Process
ΔU = 0
so ΔQ =ΔW
Isochoric Process
ΔU = ΔQ - ΔW
Adiabatic Process
Solution
Change in the internal energy of the system is
zero i.e increase in internal of one gas is equal to
decrease in internal energy of other
So
5𝑅
Δ𝑈𝐴 = 1𝑥
(𝑇 − 𝑇0 )
2 𝑓
3𝑅
7
Δ𝑈𝐵 = 1𝑥
(𝑇𝑓 − 𝑇0 )
2
3
Δ𝑈𝐴 + Δ𝑈𝐵 = 0
Solving we get 2 Tf − 3 T0 = 0
So a is correct
ΔQ = O
so ΔU = -ΔW
Isobaric process
V = Const
so ΔW = 0
ΔU= ΔQ
Question 22
The ratio of adiabatic bulk modulus and
𝐶𝑝
isothermal bulk modulus of a gas (𝛾 = 𝐶 ) is
a.
Question 16
Which one of the following statement is true about a
gas undergoing isothermal change
a. The temperature of the gas is constant
b. The pressure of the gas remains constant
c. the volume of the gas remains constant
d. The gas is completely insulated from the
surrounding’s
𝑣
𝛾−1
𝛾
b. 1
c. 𝛾
𝛾
d. 𝛾−1
Solution
𝑉Δ𝑃
Bulk Modulus is defined as 𝐵 = − Δ𝑉
For adiabatic process 𝑃𝑉 𝛾 = Constant
Differentiating partially we get Δ𝑃𝑉 𝛾 + 𝑃𝛾𝑉 𝛾−1 =
0
𝑉Δ𝑃
or − Δ𝑉 = 𝛾𝑃
For isothermal Process PV=constant or −
So ratio is equal to 𝛾
𝑉Δ𝑃
Δ𝑉
=𝑃
Question 15
Two boxes A and B containing different ideal gases are
Solution
Correct ans is a
Question 17
Three copper blocks of masses M1, M2 and M3 kg
respectively are brought into thermal contact till they
reach equilibrium. Before contact, they were
at T1, T2, T3 (T1>T2>T3). Assuming there is no heat
loss to the surroundings, the equilibrium temperature
T is (s is specific heat of copper)
Page 25 of 31
‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
a.
b.
C.
d.
line BC passes through origin, so nothing can be
said about state C So (c) and (d) are correct
𝑻𝟏 +𝑻𝟐 +𝑻𝟑
𝟑
𝑴𝟏 𝑻𝟏 +𝑴𝟐 𝑻𝟐 +𝑴𝟑 𝑻𝟑
𝑴𝟏 +𝑴𝟐 +𝑴+𝟑
𝑴𝟏 𝑻𝟏 +𝑴𝟐 𝑻𝟐 +𝑴𝟑 𝑻𝟑
𝟑(𝑴𝟏 +𝑴𝟐 +𝑴+𝟑)
𝑴𝟏 𝑻𝟏 𝒔+𝑴𝟐 𝑻𝟐 𝒔+𝑴𝟑 𝑻𝟑 𝒔
𝟑(𝑴𝟏 +𝑴𝟐 +𝑴+𝟑)
Question 19
The figure shows the P-V plot of an ideal gas taken
through a cycle ABCDA. The part ABC is a semi-circle
and CDA is half of an ellipse. Then -
Solution
Question 18
One mole of an ideal gas goes through the cyclic
process ABCA. Pressure at State A = P0
a. the process during the path A ? B is isothermal
b. heat flows out of the gas during the path B ? C ? D
c. work done during the path A ? B ? C is zero
d. positive work is done by the gas in the cycle ABCDA
d. positive work is done by the gas in the cycle ABCDA
Solution
(B) Δ𝑄 = Δ𝑈 + 𝑊
n BCD: W is negative Δ𝑈 =
𝑃2 𝑉2 −𝑃1 𝑉1
𝛾−1
= −𝑣𝑒
(D) Cycle is clockwise.
Which of the following is correct
a. Pressure at 𝐶 is
𝑃0
4
b. temperature at C is
𝑇0
4
c. 𝑊𝐴𝐵 = 𝑃0 𝑉0 ln⁡ 4
d. 𝑈𝐴 = 𝑈− 𝐵$
So
For Process AB, as temperature remains same,
this is isothermal process So, 𝑈𝐴 = 𝑈𝐵
Also
𝑃0 𝑉0 = 𝑃𝐵 × 4𝑉0
𝑃0
𝑃𝐵 =
4
Also 𝑊𝐴𝐵 = 𝑛𝑅𝑇0 𝑙𝑛𝑉2 𝑉1 = 𝑃0 𝑉0 ln⁡ 4
The process BC is not clear as it is not mentioned
More questions of this type would be collected and
filtered from these 2 links after the new lecture is
taken
https://physicscatalyst.com/heat/pv-diagramproblems-and-solutions.php
https://physicscatalyst.com/heat/thermodynamicsquestions.php
Page 26 of 31
‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
QUESTION: 20
QUESTION: 22
In an adiabatic process internal energy of gas
In an adiabatic process gas is reduced to quarter of
its volume. What would happen to its pressure?
Given ratio of specific heats γ= 2
A. Increases
B. Become twice
A.10 times increase
C. Does not change
B.10 times decrease
D. Decreases
C.16 times increase
Solution:
From the first law of thermodynamics,
we know, dU = dQ - dW ; (work done BY the system is
considered +ve)
For an adiabatic process, dQ = 0, and hence, dU = -dW
For an ideal gas expansion, we see that work done
BY the system is +ve (recall the sign convention for
work done), i.e., dW > 0.
Therefore, dU is less than 0, and thus, the internal
energy decreases.
QUESTION: 21
Find the final temperature of one mole of an ideal
gas at an initial temperature to t K.The gas does 9 R
joules of work adiabatically. The ratio of specific
heats of this gas at constant pressure and at constant
volume is 4/3.
A.(t-9)K
B.(t - 4/3)K
D.16 times decrease
Solution:
Correct Answer : C
Explanation : The adiabatic condition is given by the
relation between pressure volume and temperature
volume as:
(PV)γ = constant
where, γ = Cp/Cv is ratio of the specific heats
These relations suggest that an decrease in volume is
associated with increase in temperature
ATQ
P1(V1)γ = (P2V2)γ
=> P1(1)2 = P2(4)2
P1/P2 = 16
C.t + 3K
QUESTION: 23
D.(t - 3)K
Solution:
TInitial = t K
Work, W = 9R
Ratio of specific heats, γ = Cp / Cv = 4/3
In an adiabatic process, we have
W = R(TFinal – Tinitial) / (1-γ)
9R = R (TFinal – t) / (1 – 4/3)
TFinal – t = 9 (-1/3) = -3
TFinal = (t-3) K
Two gases X and Y kept in separate cylinders with
same initial temperature and pressure are
compressed to one third of their volume through
isothermal and adiabatic process respectively. Which
gas would have more pressure?
A.Gas X has higher temperature
B.Gas Y has higher pressure
Page 27 of 31
‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
A. Adiabaticall
C.Gas Y has lower pressure
B.Isochorically
D.Gas X and Y are at 0 atm pressure
C.Isothermally
Solution:
D.Isobarically
QUESTION: 24
Solution:
Heat is supplied to the gas, but its internal energy
does not increase. What is the process involved?
An isobaric expansion of a gas requires heat transfer
to keep the pressure constant. An isochoric process is
one in which the volume is held constant, meaning
that the work done by the system will be zero.
A.Isochoric process
QUESTION: 26
B.Isobaric process
What is not true for a cyclic process?
A.System returns to its initial state
C.Isothermal process
B.ΔU = 0
D.none of these
C.ΔW= 0
Solution:
From the first law of thermodynamics dQ = dU + dW,
so clearly for the isothermal expansion or
compression of a real gas where u = f(T) from the first
law dU = 0 which means that the entire heat supplied
is converted into work but from the second law of
thermodynamics we find that in no process can the
entire heat supplied can be converted into work
hence in reality some fraction of heat supplied is
always used to increase the internal energy of the
system.
QUESTION: 25
Minimum work is said to be done when a gas
expands
D.ΔQ = -ΔW
Solution:
As work is a path function rather than a state
function, we can easily say that work can often be
graphically represented as the area under the PV
graph. And as cyclic processes are represented as
closed shapes on PV graph it is obvious that they have
non zero area and thus work done is non zero.
27. Energy has different forms which include
a) heat
b) work
Page 28 of 31
‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
c) all of the mentioned
d) none of the mentioned
View Answer
Answer: a
Explanation: An absolute value of energy E, is not
given by the first law.
Answer: c
Explanation: Basic fact about energy.
32. In an ideal gas there are no intermolecular forces
of attraction and repulsion, and the internal energy is
a function of temperature only.
a) true
b) false
View Answer
28. Which of the following represents the energy in
storage?
a) heat
b) work
c) internal energy
d) none of the mentioned
View Answer
Answer: c
Explanation: Energy in storage is internal energy or
the energy of the system.
29. By first law of thermodynamics,
a) Q=ΔE-W
b) Q=ΔE+W
c) Q=-ΔE-W
d) Q=-ΔE+W
View Answer
Answer: b
Explanation: Q-W is the net energy stored in system
and is called internal energy of system.
30. Which of the following an be considered as the
definition of energy?
a) Q=ΔE+W
b) Q-W=ΔE
c) first law of thermodynamics
d) all of the mentioned
View Answer
Answer: d
Explanation: The first law is a particular formulation of
the principle of the conservation of energy.
31. The first law of thermodynamics gives only the
change on energy ΔE for the process.
a) true
b) false
View Answer
Answer: a
Explanation: For an ideal gas U depends only on T.
33. Which of the following is true in regard to the
energy of an isolated system?
a) dQ≠0
b) dW≠0
c) E=constant
d) all of the mentioned
View Answer
Answer: c
Explanation: For an isolated system, dQ=dW=0 and
hence, dE=0 by first law.
34. The limitation of the first law is
a) does not indicate the possibility of a spontaneous
process proceeding in a definite direction
b) it assigns a quality to different forms of energy
c) indicates the direction of any spontaneous process
d) none of the mentioned
View Answer
Answer: a
Explanation: This is the main limitation of first law and
the second law overcomes it.
35. The enthalpy of a substance(denoted by h), is
defined as
a) h=u-pv
b) h=u+pv
c) h=-u+pv
d) h=-u-pv
View Answer
Page 29 of 31
‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
Answer: b
Explanation: This is a basic definition for enthalpy.
36. In a constant volume process, internal energy
change is equal to
a) heat transferred
b) work done
c) zero
d) none of the mentioned
View Answer
Answer: a
Explanation: In a constant volume process, there is no
work other than the pdV work.
37. For an ideal gas, enthalpy becomes
a) h=u-RT
b) h=-u-RT
c) h=u+RT
d) h=-u+RT
View Answer
Answer: c
Explanation: For an ideal gas, pv=RT.
38. Enthalpy is an intensive property of a system.
a) true
b) false
View Answer
Answer: a
Explanation: Enthalpy is an intensive property
measured mostly in kJ/kg.
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39. Heat transferred at constant pressure _____ the
enthalpy of a system.
a) decreases
b) increases
c) first decreases then increases
d) first increases then decreases
View Answer
Answer: b
Explanation: At constant pressure, (dQ)=dh where
h=u+pv is the specific enthalpy of the system.
40. The enthalpy of an ideal gas depends only on the
temperature.
a) true
b) false
View Answer
Answer: a
Explanation: This is because the internal energy of an
ideal gas depends only on the temperature.
41. The enthalpy and internal energy are the function
of temperature for
a) all gases
b) steam
c) water
d) ideal gas
View Answer
Answer: d
Explanation: The enthalpy of an ideal gas depends
only on the temperature because the internal energy
of an ideal gas depends only on the temperature.
42. At constant pressure
a) pdv=d(pv)
b) dQ=du+d(pv)
c) dQ=d(u+pv)
d) all of the mentioned
View Answer
Answer: d
Explanation: For a constant pressure process,
dQ=du+pdv.
43. The specific heat of a substance at constant
volume is defined as the rate of change of ___ with
respect to ___
a) specific internal energy, temperature
b) work, pressure
c) specific internal energy, pressure
d) heat, temperature
View Answer
Answer: a
Explanation: cv=∂u/∂T at constant volume.
Page 30 of 31
‫جامعة بني سويف‬
‫كلية علوم المالحة وتكنولوجيا الفضاء‬
Faculty of Navigation Science and Space Technology
44. Heat transferred at constant _____ increases the
_____ of a system.
a) pressure, increases
b) volume, increases
c) both of the mentioned
d) none of the mentioned
View Answer
Answer: c
Explanation: At constant pressure, (dQ)=dh and at
constant volume, Q=Δu.
45. Specific heat of a substance at constant volume is
a property of the system.
a) true
b) false
View Answer
Answer: a
Explanation: Since T,v and u are the properties of the
system, specific heat at a constant volume is a
property of the system.
46. The specific heat of a substance at constant
pressure is defined as the rate of change of ___ with
respect to ___
a) work, pressure
b) enthalpy, temperature
c) enthalpy, pressure
d) heat, temperature
View Answer
a) isolated system
b) closed system
c) open system
d) none of the mentioned
View Answer
Answer: c
Explanation: Basic definition of an open system.
49. The surface of the control volume is known as the
control surface.
a) true
b) false
View Answer
Answer: a
Explanation: This is same as the system boundary of
the open system.
50. Steady flow means that the rates of flow of mass
and energy across the control surface
a) varies
b) remains constant
c) depends on the control surface
d) none of the mentioned
View Answer
Answer: b
Explanation: In a steady flow rate of flow remains
constant.
Answer: b
Explanation: cp=∂h/∂T at constant pressure.
47. Specific heat of a substance at constant pressure is
a property of the system.
a) true
b) false
View Answer
Answer: a
Explanation: cp is a property of a substance just like
cv.
48. When there is mass transfer across the system
boundary, the system is called
Page 31 of 31