# MCQ in Thermodynamics Part 3 | ECE Board Exam

(Last Updated On: March 18, 2020) This is the Multiples Choice Questions Part 3 of the Series in Thermodynamics as one of the General Engineering and Applied Sciences (GEAS) topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including past Board Questions in General Engineering and Applied Sciences (GEAS) field.

### Online Questions and Answers in Thermodynamics Series

Following is the list of multiple choice questions in this brand new series:

Thermodynamics MCQs
PART 1: MCQs from Number 1 – 50                        Answer key: PART I
PART 2: MCQs from Number 51 – 100                   Answer key: PART II
PART 3: MCQs from Number 101 – 150                 Answer key: PART III
PART 4: MCQs from Number 151 – 200                 Answer key: PART IV
PART 5: MCQs from Number 201 – 250                 Answer key: PART V
PART 6: MCQs from Number 251 – 300                 Answer key: PART VI
PART 7: MCQs from Number 301 – 350                 Answer key: PART VII
PART 8: MCQs from Number 351 – 400                 Answer key: PART VIII
PART 9: MCQs from Number 401 – 450                 Answer key: PART IX
PART 10: MCQs from Number 451 – 500                Answer key: PART X

### Continue Practice Exam Test Questions Part III of the Series

Choose the letter of the best answer in each questions.

101. What refers to the pressure at which a pure substance changes phase at a given temperature?

• A. Equilibrium pressure
• B. Saturation pressure
• C. Superheated pressure
• D. Subcooled pressure

102. What is the amount of heat needed to turn 1 kg of the substance at its melting point from the solid to liquid state?

• A. Heat of fusion
• B. Heat of vaporation
• C. Heat of condensation
• D. Heat of fission

103. What is the amount of heat needed to turn 1kg of the substance at its boiling point from the liquid to the gaseous state?

• A. Heat of fusion
• B. Heat of vaporation
• C. Heat of condensation
• D. Heat of fission

104. What refers to the amount of energy absorbed or released during a phase-change process?

• A. Molar heat
• B. Latent heat
• C. Vaporization heat
• D. Condensation heat

105. What is the latent heat of fusion of water at 1 atm?

• A. 331.1 kJ/kg
• B. 332.6 kJ/kg
• C. 333.7 kJ/kg
• D. 330.7 kJ/kg

106. What is the latent heat of vaporization of water at 1 atm?

• A. 2314.8 kJ/kg
• B. 2257.1 kJ/kg
• C. 2511.7 kJ/kg
• D. 2429.8 kJ/kg

107. What refers to the point at which the saturated liquid and saturated vapor states are the same or identical?

• A. Triple point
• B. Inflection point
• C. Maximum point
• D. Critical point

108. What is defined as the direct conversion of a substance from the solid to the vapor state or vice versa without passing the liquid state?

• A. Condensation
• B. Vaporization
• C. Sublimation
• D. Cryogenation

109. The amount of heat required to raise the temperature of 1kg of water through 1 °C is called ______.

• A. Calorie
• B. Joule
• C. BTU
• D. Kilocalorie

110. The amount of heat required to raise the temperature of 1 pound of water by 1°F is called ______.

• A. Calorie
• B. Joule
• C. BTU
• D. Kilocalorie

111. 1 British thermal unit (BTU) is equivalent to how many joules?

• A. 1016
• B. 1043
• C. 1023
• D. 1054

112. The term “enthalpy” comes from Greek “enthalpen” which means ______.

• A. Warm
• B. Hot
• C. Heat
• D. Cold

113. The ratio of the mass of vapor to the total mass of the mixture is called ______.

• A. Vapor ratio
• B. Vapor content
• C. Vapor index
• D. Quality

114. The “equation of state” refers to any equation that relates the ______ of the substance.

• A. Pressure and temperature
• B. Pressure, temperature and specific weight
• C. Temperature and specific weight
• D. Pressure, temperature and specific volume

115. In the equation Pv = RT, the constant of proportionality R is known as ______.

• A. Universal gas constant
• B. Gas constant
• C. Ideal gas factor
• D. Gas index

116. The gas constant of a certain gas is the ratio of:

• A. Universal gas constant to molar mass
• B. Universal gas constant to atomic weight
• C. Universal gas constant to atomic number
• D. Universal gas constant to number of moles

117. What is the value of the universal gas constant in kJ/kmol ∙ K?

• A. 10.73
• B. 1.986
• C. 8.314
• D. 1545

118. The mass of one mole of a substance in grams is known as ______.

• A. Molar weight
• B. Molar mass
• C. Molar volume
• D. Molar constant

119. What is defined as the energy required to raise the temperature of a unit mass of a substance by one degree?

• A. Latent heat of fusion
• B. Molar heat
• C. Specific heat capacity
• D. Specific heat

120. The ______ of a substance is the amount of heat that must be added or removed from a unit mass of the substance to change its temperature by one degree.

• A. Latent heat of fusion
• B. Molar heat
• C. Specific heat capacity
• D. Specific heat

121. What is the specific heat capacity of water in J/kg ∙°C?

• A. 4581
• B. 4185
• C. 4518
• D. 4815

122. What is the SI unit of specific heat capacity?

• A. J/kg
• B. J/kg∙ °F
• C. J/kg∙ °C
• D. J/°C

123. What is constant for a substance that is considered “incompressible”?

• A. Specific volume of density
• B. Pressure
• C. Temperature
• D. All of the above

124. If there is no heat transferred during the process, it is called a ______ process.

• A. Static
• B. Isobaric
• C. Polytropic

• A. No heat
• B. No transfer
• C. Not to be passed
• D. No transformation

126. How is heat transferred?

• A. By conduction
• B. By convection
• D. All of the above

127. What refers to the transfer of energy due to the emission of electromagnetic waves or photons?

• A. Conduction
• B. Convection
• D. Electrification

128. What refers to the transfer of energy between a solid surface and the adjacent fluid that is in motion?

• A. Conduction
• B. Convection
• D. Electrification

129. What refers to the transfer of energy from the more energetic particles of a substance to the adjacent less energetic ones as a result of interaction between particles?

• A. Conduction
• B. Convection
• D. Electrification

130. What states that the net mass transfer to or from a system during a process is equal to the net change in the total mass of the system during that process?

• A. Third law of thermodynamics
• B. Conservation of energy principle
• C. Second law of thermodynamic
• D. Conservation of mass principle

131. Which of the following statements is TRUE for an ideal gas, but not for a real gas?

• A. PV = nRT
• B. An increase in temperature causes an increase in the kinetic energy of the gas
• C. The total volume of molecules on a gas is nearly the same as the volume of the gas as a whole
• D. No attractive forces exists between the molecule of a gas

132. How does an adiabatic process compare to an isentropic process?

• A. Adiabatic heat transfer is not equal to zero; isentropic heat transfer is zero
• B. Both heat transfer = 0; isentropic: reversible
• C. Adiabatic heat transfer = 0; isentropic: heat transfer is not equal to zero
• D. Both heat transfer is not equal to zero; isentropic: irreversible

133. Which of the following is the Ideal gas law (equation)?

• A. V/T = K
• B. V= k*(1/P)
• C. P1/T1 = P2/T2
• D. PV = nRT

134. What is a measure of the ability of a material to conduct heat?

• A. Specific heat capacity
• B. Coefficient of thermal expansion
• C. Coefficient of thermal conductivity
• D. Thermal conductivity

135. What refers to the heating of the earth’s atmosphere not caused by direct sunlight but by infrared light radiated by the surface and absorbed mainly by atmospheric carbon dioxide?

• A. Greenhouse effect
• B. Global warming
• C. Thermal rise effect
• D. Ozone effect

136. What is a form of mechanical work which is related with the expansion and compression of substances?

• A. Boundary work
• B. Thermodynamic work
• C. Phase work
• D. System work

137. Thermal radiation is an electromagnetic radiation with wavelengths in _____ range.

• A. 1 to 100 µm
• B. 0.1 to 100 µm
• C. 0.1 to 10 µm
• D. 10 to 100 µm

138. What refers to the rate of thermal radiation emitter per unit area of a body?

• A. Thermal conductivity
• B. Absorptivity
• C. Emissivity
• D. Emissive power

139. What states that for any two bodies in thermal equilibrium, the ratios of emissive power to the absorptivity are equal?

• B. Newton’s law of cooling
• C. Stefan-Boltzmann law
• D. Hess’s law

140. What is considered as a perfect absorber as well as a perfect emitter?

• A. Gray body
• B. Black body
• C. Real body
• D. White body

141. What is a body that emits a constant emissivity regardless of the wavelength?

• A. Gray body
• B. Black body
• C. Real body
• D. White body

142. At same temperatures, the radiation emitted by all real surfaces is ______ the radiation emitted by a black body.

• A. Less than
• B. Greater than
• C. Equal to
• D. Either less than or greater than

143. Which is NOT a characteristic of emissivity?

• A. It is high with most nonmetals
• B. It is directly proportional to temperature
• C. It is independent with the surface condition of the material
• D. It is low with highly polished metals

144. What is the emissivity of a black body?

• A. 0
• B. 1
• C. 0.5
• D. 0.25

145. What is the absorptivity of a black body?

• A. 0
• B. 1
• C. 0.5
• D. 0.25

146. What is sometimes known as the “Fourth-power law”?

• B. Newton’s law of cooling
• C. Stefan-Boltzmann law
• D. Hess’s law

147. What states that the net change in the total energy of the system during a process is equal to the difference between the total energy entering and the total energy leaving the system during that process?

• A. Third law of thermodynamics
• B. Conservation of energy principle
• C. Second law of thermodynamics
• D. Conservation of mass principle

148. The equation Ein – Eout = ∆Esystem is known as ______.

• A. Energy conservation
• B. Energy equation
• C. Energy balance
• D. Energy conversion equation

149. What remains constant during a steady-flow process?

• A. Mass
• B. Energy content of the control volume
• C. Temperature
• D. Mass and energy content of the control volume

150. Thermal efficiency is the ratio of:

• A. Network input to total heat input
• B. Network output to total heat output
• C. Network output to total heat input
• D. Network input to total heat output

### Complete List of MCQs in General Engineering and Applied Science per topic

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