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This set of Engineering Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on Engineering Thermodynamics Set 20
Q1 | What is the effect of reheat pressure on mean temperature of heat addition Tml?
- reheat pressure is directly proportional to tml
- reheat pressure is inversely proportional to tml
- reheat pressure is equal to tml
- tml is independent of reheat pressure
Q2 | Which of the following problems are posed by increasing the number of reheats?
- cost & fabrication problems arise
- heat transfer problems arise
- frictional losses arise
- none of the mentioned
Q3 | What is the most preferable dryness fraction of the exhaust steam?
- 0.99
- 0.77
- 0.66
- 0.88
Q4 | Which of the following represents the specific volume during phase transition.
- vf-vg
- vg-vf
- vf+vg
- none of the mentioned
Q5 | An 80 litre vessel contains 4 kg of R-134a at a pressure of 160 kPa. Determine the volume occupied by the vapour phase.
- 0.0775 m3
- 0.0575 m3
- 0.0975 m3
- 0.0375 m3
Q6 | Rankine cycle comprises of
- two isentropic processes and two constant volume processes
- two isentropic processes and two constant pressure processes
- two isothermal processes and two constant pressure processes
- none of the mentioned
Q7 | In Rankine cycle, the work output from the turbine is given by
- change of internal energy between inlet and outlet
- change of enthalpy between inlet and outlet
- change of entropy between inlet and outlet
- change of temperature between inlet and outlet
Q8 | Which of the following contributes to the improvement of efficiency of Rankine cycle in a Thermal Power Plant?
- reheating of steam at intermediate stage
- regeneration use of steam for heating boiler feed water
- use of high pressures
- all of the mentioned
Q9 | A simple Rankine cycle operates the Boiler at 3 MPa with an outlet temperature of 350°C and the Condenser at 50 kPa. Assuming ideal operation and processes, what is the thermal efficiency of this cycle?
- 7.7
- 17.7
- 27.7
- 37.7
Q10 | How many types of feedwater heaters are present?
- one
- two
- three
- four
Q11 | The temperature of feedwater leaving a heater is the saturation temperature at steam extraction pressure.
- less than
- equal to
- more than
- none of the mentioned
Q12 | The following also gave two-constant equations of state.
- berthelot
- dieterici
- redlich-kwong
- all of the mentioned
Q13 | Which of the following is true about compressibility of real gases?
- z = 1
- z < 1
- z > 1
- both z < 1 and z > 1 view answer
Q14 | 1 mole of cyclohexane (z = 1.2) is filled in a container at 27oC and 4 atm, what is the volume of container?
- 3.8 liter
- 4.4 liter
- 5.6 liter
- 7.4 liter view answer
Q15 | If a relation exists among variables x,y,z then z may be expressed as a function of x and y as, dz=Mdx+Ndy .
- true
- false
Q16 | A pure substance which exists in a single phase has independent variables.
- zero
- one
- two
- three
Q17 | Which of the following is not a Maxwell equation?
- (∂t/∂v) = -(∂p/∂s)
- (∂t/∂p) = -(∂v/∂s) c) (∂p/∂t) = (∂s/∂v) d) (∂v/∂t) = -(∂s/∂p)
Q18 | The Clausius-Clapeyron equation is given by
- dp/dt = l / t(vf+vi)
- dp/dt = l / t(vf-vi)
- dt/dp = l / t(vf+vi)
- dt/dp = l / t(vf-vi)
Q19 | Water on melting and has the fusion curve with a slope.
- contracts, negative
- contracts, positive
- expands, negative
- expands, positive
Q20 | At the triple point, l(sublimation) = l(vaporization) – l(fusion).
- true
- false
Q21 | The slope of sublimation curve is the slope of the vaporization curve at triple point.
- equal to
- less than
- greater than
- none of the mentioned
Q22 | An application requires R-12 at −140°C. The triple-point temperature is −157°C. Find the pressure of the saturated vapour at the required condition.
- 0.0058 kpa
- 0.0098 kpa
- 0.0068 kpa
- 0.0088 kpa
Q23 | The expression which represents the pressure exerted by a gas is
- nvrt
- nrt/v
- v/nrt
- 1/nvrt
Q24 | Which of the following relation is correct?
- mole fraction of the kth gas = moles of the kth gas / total number of moles of gas
- partial pressure of kth gas = (mole fraction of the kth gas)*(sum of the partial pressures)
- sum of mole fractions of all the gases is unity
- all of the mentioned
Q25 | The total entropy of a mixture of gases is the of the partial entropies.
- average
- weighted mean
- sum
- difference of the highest and the lowest