Engineering Thermodynamics MCQs

Question 1

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 $$\gamma $$ = Ratio of specific heats)

Accepted Answer

All of these

Answer

$$\frac{{{{	ext{p}}_1}{{	ext{v}}_1} - {{	ext{p}}_2}{{	ext{v}}_2}}}{{\gamma - 1}}$$

Answer

$$\frac{{{	ext{mR}}\left( {{{	ext{T}}_1} - {{	ext{T}}_2}} ight)}}{{\gamma - 1}}$$

Answer

$$\frac{{{	ext{mR}}{{	ext{T}}_1}}}{{\gamma - 1}}\left( {1 - \frac{{{{	ext{p}}_2}{{	ext{v}}_2}}}{{{{	ext{p}}_1}{{	ext{v}}_1}}}} ight)$$

Question 2

According to First law of thermodynamics,

Accepted Answer

Total energy of a system remains constant

Answer

Total internal energy of a system during a process remains constant

Answer

Work-done by a system is equal to the heat transferred by the system

Answer

Internal energy, enthalpy and entropy during a process remain constant

Question 3

According to Kelvin-Planck’s statement of second law of thermodynamics,

Accepted Answer

It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

Answer

It is possible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

Answer

It is impossible to construct a device which operates in a cyclic process and produces no effect other than the transfer of heat from a cold body to a hot body

Answer

None of the above

Question 4

According to Kelvin-Planck's statement of second law of thermodynamics,

Accepted Answer

It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

Answer

It is possible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

Answer

It is impossible to construct a device which operates in a cyclic process and produces no effect other than the transfer of heat from a cold body to a hot body

Answer

None of the above

Question 5

The heat and work are mutually convertible. This statement is called __________ law of thermodynamics.

Accepted Answer

First

Answer

Zeroth

Answer

Second

Answer

Third

Question 6

Which of the following statement is correct according to Clausis statement of second law of thermodynamics?

Accepted Answer

It is impossible to transfer heat from a body at a lower temperature to a body at a higher temperature, without the aid of an external source.

Answer

It is possible to transfer heat from a body at a lower temperature to a body at a higher temperature.

Answer

It is possible to transfer heat from a body at a lower temperature to a body at a higher temperature by using refrigeration cycle.

Answer

None of the above

Question 7

Which of the following is the correct statement of the second law of thermodynamics?

Accepted Answer

All of the above

Answer

There is a definite amount of mechanical energy, which can be obtained from a given quantity of heat energy

Answer

It is impossible to transfer heat from a body at a lower temperature to a higher temperature, without the aid of an external source

Answer

It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

Question 8

One kg of ethylene (C2H4) requires 2 kg of oxygen and produces $$\frac{{22}}{7}$$ kg of carbon dioxide and __________ kg of water or steam.

Accepted Answer

$$\frac{9}{7}$$

Answer

$$\frac{{11}}{7}$$

Answer

$$\frac{7}{4}$$

Answer

$$\frac{{11}}{4}$$

Question 9

1 kgf/cm2 is equal to

Accepted Answer

735.6 mm Hg

Answer

760 mm Hg

Answer

Zero mm Hg

Answer

1 mm Hg