Topic: Thermodynamics (Test 1)



Topic: Thermodynamics
Q.1
The picture of heat as a fluid was discarded in favor of the modern concept of heat as a form of energy because
A. Count Rumford observed that boring of brass cannon generated a lot of smoke
B. Count Rumford observed that boring of brass cannon generated a lot of noise
C. Count Rumford observed that boring of brass cannon generated a lot of heat
D. Count Rumford observed that boring of brass cannon generated a lot of dust
Answer : Option C
Explaination / Solution:

If heat were actually a substance, as many scientists of the time believed, it was difficult to see how so much of it could be produced during the boring of a metal cannon. Rumford showed that the amount of heat was not related to the quantity of filings produced

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Q.2
Thermodynamics is the branch of physics that deals with.
A. the concepts of heat and temperature and the inter-conversion of heat and other forms of energy
B. the concepts of heat and noise and the inter-conversion of noise and other forms of energy
C. the concepts of kinetic energy and temperature and the inter-conversion of mechanical and other forms of energy
D. the concepts of heat and dust and the inter-conversion of heat and other forms of matter
Answer : Option B
Explaination / Solution:

Thermodynamics is a branch of physics concerned with heat and temperature and their relation to energy and work. It deals with the relations between heat and other forms of energy (such as mechanical, electrical, or chemical energy), and, by extension, of the relationships between all forms of energy.

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Q.3
Thermodynamic state of a system is an equilibrium state
A. if the macroscopic variables that characterize the system change decrease in time
B. if the macroscopic variables that characterize the system change linearly in time
C. if the macroscopic variables that characterize the system change randomly
D. if the macroscopic variables that characterize the system do not change in time
Answer : Option D
Explaination / Solution:

In thermodynamic equilibrium there are no net macroscopic flows of matter or of energy, either within a system or between systems.

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Q.4
Adiabatic wall is –
A. a thermally conducting wall that does not allow flow of heat from one body to many
B. a thermally insulating wall that does not allow flow of heat from one body to another
C. a thermally insulating wall that does allows flow of heat from one body to another
D. a thermally conducting wall that does not allow flow of heat from one body to another
Answer : Option B
Explaination / Solution:

In thermodynamics, an adiabatic wall between two thermodynamic systems does not allow heat or matter to pass across it. In theoretical investigations, it is sometimes assumed that one of the two systems is the surroundings of the other.

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Q.5
Diathermic wall is
A. a thermally conducting wall that does not allow flow of heat from one body to another
B. a thermally insulating wall that does not allow flow of heat from one body to many
C. a thermally conducting wall that allows flow of heat from one body to another
D. a thermally insulating wall that allows flow of heat from one body to another
Answer : Option C
Explaination / Solution:

A wall which prevents thermal interaction is known as adiabatic wall and a system enclosed within an adiabatic wall is called thermally isolated. If exchange of heat takes place between the system and surroundings through the boundary wall, the boundary is called diathermic wall.

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Topic: Thermodynamics Tag:
Q.6
Zeroth Law of Thermodynamics
A. states that two systems in thermal equilibrium with a third system separately cannot be in thermal equilibrium with each other
B. states that two systems in thermal equilibrium with a third system simultaneously are never in thermal equilibrium with each other
C. states that two systems in thermal equilibrium with a third system separately are in thermal equilibrium with each other
D. states that a system in thermal equilibrium with a third system separately is in thermal equilibrium with any other
Answer : Option C
Explaination / Solution:

The zeroth law of thermodynamics states that if twothermodynamic systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other.

More simply:

if 

It is called the zeroth (0th) law of thermodynamics because it was discovered after the others, but people thought it was more important so they wanted to give it a number before the other laws.


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Q.7
Internal energy of a system
A. is the change in the sum of the kinetic energies and potential energies of the molecules of the system
B. is the change in the difference of the kinetic energies and potential energies of the molecules of the system
C. is the difference of the kinetic energies and potential energies of the molecules of the system
D. is the sum of the kinetic energies and potential energies of the molecules of the system
Answer : Option D
Explaination / Solution:

In thermodynamics, the internal energy of a system is the energy contained within the system. It is the energy in a system arising from the relative positions and interactions of its parts.

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Q.8
Internal energy of a system is
A. a discrete variable
B. a random variable
C. a complex variable
D. a state variable
Answer : Option D
Explaination / Solution:

A state function describes the equilibrium state of a system. For example, internal energy, enthalpy, and entropy are state quantities because they describe quantitatively an equilibrium state of a thermodynamic system, irrespective of how the system arrived in that state.

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Q.9
First Law of Thermodynamics is

The first law of thermodynamics is the application of the conservation of energy principle to heat and thermodynamic processes:

A. the general law of conservation of momentum applied to any system in which the energy transfer from or to the surroundings is taken into account
B. the general law of conservation of angular momentum applied to any system in which the energy transfer from or to the surroundings is taken into account
C. the general law of conservation of mass applied to any system in which the energy transfer from or to the surroundings is taken into account
D. the general law of conservation of energy applied to any system in which the energy transfer from or to the surroundings is taken into account
Answer : Option D
Explaination / Solution:
No Explaination.


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Q.10

If Q is the energy supplied to the system U the change in internal energy, and W the work done on the environment, First Law of Thermodynamics states that


A. Δ U + ΔW = 0
B. Δ Q = ΔU - ΔW
C. Δ Q = ΔU × ΔW
D. Δ Q = ΔU + ΔW
Answer : Option D
Explaination / Solution:

Heat given to a system is equal to the sum of increase in its internal energy and the work done by the system against the surroundings.

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