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This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on Thermodynamics Set 3
Q1 | In the polytropic process equation pvn = constant, if the value of n is infinitely large the process is termed as
- Adiabatic
- Constant volume
- Isothermal
- Constant pressure
- Constant temperature
Q2 | The ratio of the rise in temperature of a gas when compressed adiabatically to that when compressed isothermally to the same extent is
- More than 1
- Less than 1
- Equal to 1
- Depends on the gas
- None of the above
Q3 | Other factors remaining constant, if the temperature of sink is increased, the efficiency of the Carnot engine will
- increase or decrease depending upon temperature ratio
- will not change
- Pulsejet
- increase
- decrease
Q4 | One of the most efficient engines ever developed operates between 2100 k and 700 k. Its actual efficiency is 40%. What percentage of its maximum possible efficiency is this?
- 40%
- 33.30%
- 60%
- Pulsejet
- 66.67%
Q5 | For any reversible process, the change in entropy of the system and surroundings is
- Negative
- Zero
- Unity
- Infinite
- Positive
Q6 | If all the variables of a steam are in-dependent of time it is said to be in
- Unsteady flow
- Uniform flow
- Steady flow
- Closed flow
- Constant flow
Q7 | Entropy of mixing is always
- positive
- Zero
- Negative
- Pulsejet
Q8 | A system comprising a single phase is called a
- Open system
- Isolated system
- Closed system
- Homogeneous system
- Heterogeneous system
Q9 | An open system
- Is a specified region where transfers of energy and/or mass take place
- Is a region of constant mass and only energy is allowed to cross the boundaries
- Cannot transfer either energy or mass to or from the surroundings
- Has a mass transfer across its boundaries, and the mass within the system is not necessarily constant
- None of the above
Q10 | In the regenerative cycle
- Power is generated in two stages
- Part of the steam is withdrawn from the turbine and is utilised in heating the exhaust steam
- Steam is reheated after expansion and again used
- Part of the steam is withdrawn from the turbine and is used in heating the steam being supplied to the turbine
- Part of the steam is withdrawn from the turbine and is used in heating the feed water
Q11 | Which of the following is a path function quantity?
- Work done
- Pressure
- Pulsejet
- Temperature
- Enthalpy
Q12 | An ordinary mercury thermometer can be used for temperatures about
- 200?C
- 400?C
- 300?C
- 100?C
- 500?C
Q13 | Triple point
- Occurs in sublimation
- Occurs in a mixture of two or more gases
- Is the range of temperature within which three constituents simultaneously change phase
- Is that point where three phases solid, liquid and gas exist together
- None of the above
Q14 | The characteristics of a control volume are
- The volume shape and position with respect to an observer may change
- The volume shape and position with respect to an observer are fixed
- There is no material flow across the boundary
- Pulsejet
- There is material flow across the boundary
Q15 | The gas turbine works on
- Rankine cycle
- Brayton cycle
- Erricson cycle
- Otto cycle
- Carnot cycle
Q16 | All of the following are intensive properties EXCEPT
- Viscosity
- Mass
- Pulsejet
- Density
- Temperature
Q17 | A body of weight 100 N falls freely through a distance of 10 m against an atmospheric drag force of 5 N. Considering the body as the system, the work interaction is
- 1000 Nm
- Pulsejet
- 1050 Nm
- 50 Nm
- 950 Nm
Q18 | In a steam turbine when steam expands, the entropy
- Decreases exponentially
- Does not change
- Increases exponentially
- Decreases linearly
- Increases linearly
Q19 | Of the following first law statements, choose the one that is wrong
- the net heat transfer equals the network for a cycle
- the heat transfer equals the work plus the energy change
- the heat transfer cannot exceed the work done
- Pulsejet
- the energy of an isolated system remains constant
Q20 | If the dryness fraction of a sample by throttling calorimeter is 0.8 and that by separating calorimeter is also 0.8, then the actual dryness fraction of sample will be taken as
- Volume change is negligible
- 1
- 0.8
- 0.5
- 0.64
Q21 | Work done by an expanding gas under adiabatic condition results in
- Temperature decrease
- Temperature decreases first and then increase
- Temperature increase first and then decrease
- No change in temperature
- Temperature increase
Q22 | Carburetted water gas is obtained by
- heating water at high temperature in a copper vessel
- Burning oil
- spraying oil into a carburettor filled with hot brick elieckar work through which the gases pass
- Pulsejet
- Passing alternately steam and air through while hot carbon
Q23 | A process which does not dissipate available energy is known as
- Isothermal process
- Energyless process
- Adiabatic process
- Ideal process
- Frictionless process
Q24 | The weight of 1 cu-m of carbon dioxide at NTP if the characteristic gas constant is 19.28 kg metre/kg/?C, would be
- 3.924 kg
- 2.5 kg
- 1.962 kg
- 1 kg
- 1.5 kg
Q25 | The ability of gasoline to resist detonation during combustion is given by
- iso-octane number
- heptane number
- Pulsejet
- Cetane number
- Octane number