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

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

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

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

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

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

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

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

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 _________
b) Isentropic efficiency
c) Thermal efficiency
d) Mechanical efficiency

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