Thermodynamics Questions and Answers Part-8

1. The transfer of heat between two bodies in direct contact is called
a) radiation
b) convection
c) conduction
d) none of the mentioned

Answer: c
Explanation: This is the definition of conduction.

2. 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

Answer: d
Explanation: The direction of heat transfer is taken from the high temperature system to the low temperature system.

3. In the equation, dQ=TdX
a) dQ is an inexact differential
b) dX is an exact differential
c) X is an extensive property
d) all of the mentioned

Answer: d
Explanation: This is because heat transfer is a path function.

4. 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

Answer: b
Explanation: This is the definition of convection.

5. 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

Answer: b
Explanation: It is the property of specific heat.

6. 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

Answer: a
Explanation: c=Q/(m*Δt)

7. Heat and work are
a) path functions
b) inexact differentials
c) depend upon the path followed
d) all of the mentioned

Answer: d
Explanation: It is an important point to remember regarding heat and work transfer.

8. Latent heat is taken at
a) constant temperature
b) constant pressure
c) both of the mentioned
d) none of the mentioned

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.

9. 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

Answer: c
Explanation: It is a general fact about latent heat.

10. Heat transfer and work transfer are
a) boundary phenomena
b) energy interactions
c) energy in the transit
d) all of the mentioned

Answer: d
Explanation: It is an important point to remember regarding heat and work transfer.