Thermodynamics Quizzes Posted on December 29, 2018 by Editor Thermodynamics is the branch of physics that has to do with heat and temperature and their relation to energy and work. The behavior of these quantities is governed by the four laws of thermodynamics, irrespective of the composition or specific properties of the material or system in question. The laws of thermodynamics are explained in terms of microscopic constituents by statistical mechanics. Thermodynamics applies to a wide variety of topics in science and engineering , especially physical, chemistry and chemical engineering and mechanical engineering. The formation of scale boiler leads to decrease in efficiency of boiler increase in efficiency of boiler increase in heat transfer decrease in maintenance of boiler What is the pH value of water permissible for boiler? slightly less than 7 slightly more than 7 7 4 When the rate of evaporation of water is zero, the relative humidity of the air is 0% 50% 100% unpredictable What is the difference between work done by a system through an ideal reversible process and actual work done by the system called? irreversibility degradation dissipation all of the above At any point on the saturation curve in psychometric chart, the dry bulb temperature is always less than the corresponding wet bulb temperature more than the corresponding wet bulb temperature equal to the corresponding wet bulb temperature cannot predict On psychrometric chart, wet bulb temperature lines are horizontal with uniformly spaced horizontal with non-uniformly spaced inclined with uniformly spaced inclined with non-uniformly spaced For the same capacity of plant, the COP of the vapour absorption refrigeration system is lower than the COP of the vapour compression refrigeration system higher than the COP of the vapour compression refrigeration system same as the COP of the vapour compression refrigeration system cannot say The vapour absorption refrigeration system is more noisy than the vapour compression refrigeration system more silent than the vapour compression refrigeration system equally noisy as the vapour compression refrigeration system it depends upon plant capacity Which type of energy is required to expend in vapour absorption refrigeration system? high-grade energy low-grade energy medium-grade energy none of the above What is an advantage using analyser-rectifier in aqua-ammonia absorption system? it makes ammonia-water solution strong it prevents expansion valve from blocking due to ice formation both a. and b. none of the above What is the purpose of using free-shaft turbine? to increase net work output of the turbine to decrease net work output of the turbine to increase part load efficiency none of the above What is a free-shaft turbine? the separate turbine which is used only to run compressor the separate turbine which is placed on another shaft on which the compressor is not run the separate turbine which is used only to run condenser all of the above In vapour refrigeration cycle, which of the following is used for expansion? Throttling valve or capillary tube Expansion engine Both of the mentioned None of the above A condenser must_____and then____the compressed refrigerant desuperheat, evaporate superheat, evaporate desuperheat, condense superheat, condese Entropy is : the total mass outside of substance the total energy inside the substance the temperature remains constant None of above The CHARLES'S law describes relation between: Pressure and area Mass and volume Temperature and volume Temperature and pressure The relationship between amount and volume discovered by REVERSIBLE LAW IRREVERSIBLE LAW ZEROTH LAW AVOGADRO'S LAW if two thermodynamic system each are in thermal equilibrium with a third one, then they are in thermal equilibrium with each other it describes from: First law of thermodynamics Zeroth law Second law of thermodynamics None of above What is the unit of work Joule (J) Joule/Kelvin Kg/m None of above In thermodynamics, the measure of average thermal of the molecule in a substance is called as Work Heat thermal energy Temperature In thermodynamics, the motion of thermal energy is called as: Heat Convection Radiation Temperature Work done in all reversible process is equal: True False In an open system, for maximum work, the process must be entirely Irreversible Reversible Adiabatic None of above Which of the following system is true for a steady flow system? mass does not equal mass entering can be more or less than the mass leaving mass does not enter or leave the system mass entering = mass leaving A cylinder/piston contains 100L of air at 25°C, 110 kPa. The air is compressed in a reversible polytropic process to a final state of 200°C, 800 kPa. Assume the heat transfer is with the ambient at 25°C. Find the work done by the air -21.28 kJ -31.28 kJ -41.28 kJ -11.28 kJ A piston cylinder contains air at 600 kPa, 290 K and a volume of 0.01m^3. A constant pressure process gives 54 kJ of work out. Find the final volume of the air. 0.05 m^3 0.01 m^3 0.10 m^3 0.15 m^3 A piston-cylinder device initially contains air at 150 kPa and 27°C. At this state, the volume is 400 litre. The mass of the piston is such that a 350 kPa pressure is required to move it. The air is now heated until its volume has doubled. Determine the total heat transferred to the air. 767 kJ 747 kJ 757 kJ 777 kJ Which of the following operations occur in a vapour refrigeration cycle? compression cooling and condensing expansion and evaporation All of the mentioned Which of the following system is correct: Intake-compression-exhaust-combustion Intake-combustion-exhaust-compression Intakae-combustion-compression-exhasut Intake-compression-combustion-exhaust In which process, there is no heat flow takes place between system and surrounding Isothermal process Isobaric process Isochoric process Adiabatic process In expansion process, which of the following remains constant? internal energy enthalpy work done heat supplied The transfer of heat between two bodies in direct is called conduction convection radiation none of above Superheating of vapour and subcooling of liquid ____ the refrigerating effect. Decrease Increase No change None of above Which of the following recommended in a refrigeration cycle? superheating of vapour subcooling of liquid both are the correct none of above Heat flow into a system is taken to be ____, and heat flow out of the system is taken as ____ negative, negative positive, positive positive, negative negative, positive The evaporation process is constant volume reversible process reversible adiabatic process constant pressure reversible process adiabatic throttling process One tonne of refrigeration is given as the rate of heat removal from surroundings equivalent to heat required for melting one tonne of ice in a day False True The specific heat of the substance is defined as the amount of heat required to raise a unit mass of the substance through a unit rise in temperature. True False Which of the following is true? latent heat of fusion is not much affected by pressure latent heat of vaporization is highly sensitive to pressure both are the correct none of above In the equation, dQ=TdX dQ is an inexact differential dX is an exact differential X is the extensive property all of correct A polytropic process (n=-1) starts with P=0, V=0 and ends with V=600 kPa, V= 0.01m^{3}. Find the boundary work done. 4 kJ 2 kJ 1 kJ 3 kJ A cylinder/piston contains 1kg methane gas at 100 kPa, 20°C. The gas is compressed reversibly to a pressure of 800 kPa. Calculate the work required if the process is isothermal. -216.0 kJ -516.0 kJ -416.0 kJ -316.0 kJ The losses in condenser are__ large small always constant none of above The thermal effieciency of cycle is Q2/Wnet Wnet/Q2 Wnet/Q1 Q1/Wnet Which of the following losses occur in a cycle? piping losses pump losses turbine losses all of above The heat transfer and the pressure drop reduces the availability of steam. True False The efficiency of Carnot cycle is____the efficiency of Rankine cycle is greater than less than equal to none above The main losses in turbine include: friction losses heat loss to surroundings both are the correct none of above There is transfer of energy as work but not as heat that describes from : Entropy process Adiabatic process Isentropic process Isothermal process A piston cylinder contains 0.5 kg of airt at 500 kPs and 500 K. The air expands in a process so pressure is linearly decreasing with volume to fnal state of 100 kPa and 300 kPa. Find the work in the process 66.1 kJ 56.1 kJ 76.1 kJ 86.1 kJ The process, during which the volume of the system remains constant, is called as: Isothermal process Reversible process Isobaric process Isochoric process When the system undergoes change from one state to the other, but its temperature remains constant is said to be : Isothermal process Adiabatic process Loss of energy None of above The process during which the pressure of the system remains constant is called as: Isochoric process Isothermal process Isobaric process Adiabatic compression process The evaporator produces cooling or refrigerating effect False True The relation between Kelvin and Celsius temperature scale is: K= degree Celsius + 273. K= degree Celsius + 284 K= degree Celsius + 274 K= degree Celsius + J/K Compression can be: Dry compression Wet compressionn Both are correct None of above Water____on the melting and has the fusion curve with a___slope. contracts, positive expands, negative expands, positive contracts, negative A mass of 1kg of air contained in a cylinder at 1000 K, 1.5 MPa, expands in a reversible adiabatic process to 100 kPa. Calculate the work done during the process using Constant specific heat. 286.5 kJ 486.5 kJ 386.5 kJ 586.5 kJ Heat transfer and work transfer are boundary phenomena energy interaction energy in the transit all above mentioned 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)