Engineering Questions with Answers - Multiple Choice Questions
MCQs on Thermodynamic Relations
1 - Question
The symbol of Helmholtz free energy is_________
a) A
b) H
c) B
d) E
View Answer
a
Explanation: Helmholtz free energy is defined as the thermodynamic potential that measures the useful work obtained from a closed thermodynamic system. It is done at a constant volume and temperature. IUPAC name is ‘A’.
2 - Question
Which among the following is the formula for Helmholtz free energy?
a) U+TS
b) U+TV
c) U-TS
d) UTV
View Answer
c
Explanation: Helmholtz free energy is defined as the thermodynamic potential that measures the useful work obtained from a closed thermodynamic system. It is done at a constant volume and temperature. IUPAC name is ‘A’. (A= U-TS).
3 - Question
What is the unit of Helmholtz free energy?
a) Kelvin
b) Joule
c) Kilowatt
d) Newton
View Answer
b
Explanation: Helmholtz free energy is defined as the thermodynamic potential that measures the useful work obtained from a closed thermodynamic system. The SI unit of Helmholtz free energy is Joule.
4 - Question
What is the symbol for Gibbs free energy?
a) A
b) H
c) G
d) E
View Answer
c
Explanation: Gibbs free energy is defined as the thermodynamic potential that is used to calculate the maximum amount of reversible work. It takes place at a constant pressure and temperature. The IUPAC name for Gibbs free energy is ‘G’.
5 - Question
Gibbs free energy is also known as______
a) Free energy
b) Free entropy
c) Free enthalpy
d) Free motion
View Answer
c
Explanation: Gibbs free energy is defined as the thermodynamic potential that is used to calculate the maximum amount of reversible work. Gibbs free energy is also known as free enthalpy. It takes place at a constant pressure and temperature.
6 - Question
What is the unit of Gibbs free energy?
a) Kelvin
b) Joule
c) Kilowatt
d) Newton
View Answer
b
Explanation: Gibbs free energy is defined as the thermodynamic potential that is used to calculate the maximum amount of reversible work. It takes place at a constant pressure and temperature. The SI unit is Joule.
7 - Question
Which among the following is the formula for Gibbs free energy?
a) H-T∆S
b) H-T
c) T∆S
d) H-S
View Answer
a
Explanation: Gibbs free energy is defined as the thermodynamic potential that is used to calculate the maximum amount of reversible work. It takes place at constant temperature and pressure. It is given by H-T∆S.
8 - Question
All the energy relations satisfy the mathematical condition in thermodynamics.
a) True
b) False
View Answer
a
Explanation: All the thermodynamic energy relations satisfy the mathematical condition of being a set of continuous variables. They are a function of state variables themselves.
9 - Question
The performance of a flow device is expressed in terms of _________
a) Adiabatic efficiency
b) Isentropic efficiency
c) Thermal efficiency
d) Mechanical efficiency
View Answer
b
Explanation: The performance of a flow device is expressed in terms of its isentropic efficiency. The actual performance of the device is compared with that of its isentropic device. It happens at the same inlet and exit conditions.
10 - Question
Isentropic efficiency is defined as ________
a) The power output of actual turbine/ power output if the turbine were isentropic
b) The power input of actual turbine/ power output if the turbine were isentropic
c) The power output of actual turbine/ power output if the turbine were adiabatic
d) The power output of actual turbine/ power output if the turbine were polytropic
View Answer
a
Explanation: The performance of a flow device is expressed in terms of its isentropic efficiency. The actual performance of the device is compared with that of its isentropic device. It happens at the same inlet and exit conditions.