Description : ick out the undesirable property for a good refrigerant. (A) High thermal conductivity (B) Low freezing point (C) Large latent heat of vaporisation (D) High viscosity
Last Answer : (D) High viscosity
Description : Why high latent heat of vaporisation is desirable in a refrigerant ?
Last Answer : A high latent heat of vaporisation of refrigerant results in small amount of refrigerant and thus lesser circulation system of refrigerant for same tonnage.
Description : Entrainer used in Azeotropic distillation should (A) Form a low boiling azeotrope with one of the constituents of the mixture (B) Form a new azeotrope of low relative volatility with one of the ... (C) Have high latent heat of vaporisation (D) Have high viscosity to provide high tray efficiency
Last Answer : (A) Form a low boiling azeotrope with one of the constituents of the mixture
Description : Which of the following is an undesirable characteristic of a refrigerant? (A) It should be non-explosive (B) It should have a sub-atmospheric vapor pressure at the temperature in refrigerator coils (C) Its vapor pressure at the condenser temperature should be very high (D) None of these
Last Answer : (B) It should have a sub-atmospheric vapor pressure at the temperature in refrigerator coils
Description : Clausius-Clapeyron Equation gives accurate result, when the (A) Vapour pressure is relatively low and the temperature does not vary over wide limits (B) Vapour obeys the ideal gas law and the latent heat of ... is negligible compared with that in the vapour state (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of ... 3.06 10 5 (B) 6.12 10 5 (C) 7.24 10 5 (D) 9.08 10
Last Answer : (A) 3.06 × 10
Description : Which of the following is an undesirable characteristic for the solvent used in gas absorption? (A) Low vapor pressure (B) Low viscosity (C) High gas solubility (D) None of these
Last Answer : (D) None of these
Description : Steam at 1000C causes more severe burns than water at 100° C because (1) steam has no specific heat capacity (2) steam has latent heat of vaporisation (3) water has no specific heat capacity (4) water has latent heat of fusion
Last Answer : steam has latent heat of vaporisation
Description : The critical pressure at which the latent heat of vaporisation of steam becomes zero is __________ Kg/cm2. (A) 273.15 (B) 225.65 (C) 100.03 (D) 373.15
Last Answer : (B) 225.65
Description : Which of the following is not a desirable property of a refrigerant (a) highmisibility with oil (b) low boiling point (c) good electrical conductor (d) large latent heat
Last Answer : Ans: c
Description : Heat sensitive materials with very high latent heat of vaporisation may be economically separated using (A) Liquid extraction (B) Distillation (C) Evaporation (D) Absorption
Last Answer : (A) Liquid extraction
Description : The solvent used in liquid extraction should not have high latent heat of vaporisation, because (A) The pressure drop and hence the pumping cost will be very high (B) It cannot ... by distillation may be prohibitively high (D) It will decompose while recovering by distillation
Last Answer : (C) Its recovery cost by distillation may be prohibitively high
Description : In distillation column design, the McCabe-Thiele procedure is inadequate and a Ponchan-Savarit procedure is needed, when (A) Saturated feed is not used (B) An azeotrope forms (C) The latent ... vaporisation of the more and less volatile components are greatly different (D) A total condenser is used
Last Answer : (D) A total condenser is used
Description : When the solvent dissolves very little of solute, then (A) Solvent of low latent heat of vaporisation should be used (B) Solvent of low freezing point should be used (C) Large quantity of solvent is required to extract the solute (D) Very small quantity of solvent is required
Last Answer : (C) Large quantity of solvent is required to extract the solute
Description : An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a (A) Boiler (B) Heat exchanger (C) Recuperator (D) Regenerato
Last Answer : (B) Heat exchanger
Description : In a cooling tower, water becomes cool by (A) Loosing sensible heat (B) Heat transfer to surroundings (C) Vaporisation due to heat loss to air (D) Loosing latent heat
Last Answer : (A) Loosing sensible heat
Description : Gibbs free energy per mole for a pure substance is equal to the (A) Latent heat of vaporisation (B) Chemical potential (C) Molal boiling point (D) Heat capacity
Last Answer : (B) Chemical potential
Description : Which of the following is Clausius-Clapeyron Equation for vaporisation of an ideal gas under the condition that the molar volume of liquid is negligible compared to that of the vapor? (A) d ln p/dt = Hvap/RT2 (B) d ln p/dt = RT2/Hvap (C) dp/dt = RT2/Hvap (D) dp/dt = Hvap/RT2
Last Answer : (A) d ln p/dt = Hvap/RT2
Description : Removal of __________ heat is involved in the condensation of a vapor under saturated conditions. (A) Super (B) Sensible (C) Latent (D) Both (B) & (C)
Last Answer : (B) Sensible
Description : Which of the following is an undesirable property of a manometricliquid? (A) Non-sticky & non-corrosive nature (B) High vapour pressure (C) Low viscosity & surface tension (D) Low co-efficient of thermal expansion
Last Answer : (B) High vapour pressure
Description : Pick out the wrong statement. (A) The condensing film co-efficient is about 3 times lower for vertical condenser as compared to the equivalent horizontal condenser for identical situation ( ... in a heat exchanger is controlled by the value of the film co-efficient, which is higher
Last Answer : (D) Overall heat transfer co-efficient in a heat exchanger is controlled by the value of the film co-efficient, which is higher
Description : The refrigerant for a refrigerator should have (a) high sensible heat (b) high total heat (c) high latent heat (d) low latent heat
Description : Choose the correct statement (a) A refrigerant should have low latent heat (b) If operating temperature of system is low, then refrigerant with low boiling point should be used (c) Pre-cooling and sub-cooling bf refrigerant are same (d) Superheat and sensible heat of a. refrigerant are same
Last Answer : Ans: b
Description : At lower temperatures and pressures, the latent heat of vaporization of a refrigerant (a) decreases (b) increases (c) remains same (d) depends on other factors
Description : Rate of heat transfer by vaporisation from pools of water is affected by the (A) Nature of heating surface and distribution of bubbles (B) Surface tension of water (C) Viscosity of water (D) All (A), (B) and (C)
Description : Only small amount of evaporation of water produces large cooling effects because of its (A) Large latent heat (B) Low viscosity (C) Small latent heat (D) None of these
Last Answer : (A) Large latent heat
Description : Which of the following is an undesirable property in a tower packing? (A) Large surface per unit volume (B) Large free cross-section (C) Low weight per unit volume (D) Large weight of liquid retained
Last Answer : (D) Large weight of liquid retained
Description : A coal with high ash content is undesirable, as (A) It is abrasive to the coal pulveriser (i.e. ball mill) and the combustion chamber (B) The ash in molten condition gets absorbed in the pores of the ... and stick to the boiler tubes thereby reducing the heat transfer (D) All (A), (B) and (C)
Description : An ideal liquid refrigerant should (A) Not have a sub-atmospheric vapour pressure at the temperature in the refrigerator coils (B) Not have unduly high vapour pressure at the condenser temperature (C) Both (A) and (B) (D) Have low specific heat
Last Answer : (C) Both (A) and (B)
Description : Pick out the wrong statement. (A) Heat transfer by radiation cannot occur across an absolute volume (B) In case of a shell and tube heat exchanger, the pressure drop through the shell is ... The amount of heat involved in the condensation or vaporisation of 1 kg of a fluid is the same
Last Answer : (A) Heat transfer by radiation cannot occur across an absolute volume
Description : To obtain integrated form of Clausius-Clapeyron equation, ln (P2/P1) = (∆HV/R) (1/T1- 1/T2) from the exact Clapeyron equation, it is assumed that the (A) Volume of the liquid phase is negligible compared to ... gas (C) Heat of vaporisation is independent of temperature (D) All (A), (B) & (C)
Last Answer : (D) All (A), (B) & (C)
Description : Pick out the wrong statement. (A) Bubble size increases with the dynamic viscosity of the liquid in case of nucleate pool boiling (B) Thermal conductivity of a dry material is more than ... in kg/hr in an evaporator (D) Vaporisation of organic substances in evaporator mostly causes foam formation
Last Answer : (B) Thermal conductivity of a dry material is more than that of the damp material
Description : Specific __________ does not change during a phase change (e.g. sublimation, melting, vaporisation etc.). (A) Entropy (B) Internal energy (C) Enthalpy (D) Gibbs free energy
Last Answer : (D) Gibbs free energy
Description : __________ determination is not a very significant and important test for gasoline. (A) Gum & sulphur content (B) Viscosity (C) Octane number (D) Reid vapor pressure
Last Answer : (B) Viscosity
Description : The snow on the mountains does not melt all at once when it is heated by the sun because _____ A. It becomes very hard It B. It reflects most of the heat from the sun C. It has a low specific heat capacity D. It has a high latent heat of fusion
Last Answer : ANSWER: B
Description : The snow on the mountains does NOT melt all at once when it is heated by the sum because: (1) It becomes very hard (2) It reflects most of the heat from the sum (3) it has a low specific heat capacity (4) it has a high latent heat of fusion
Last Answer : (2) It reflects most of the heat from the sum Explanation: Newly formed snow reflects about 90 per cent of the sunlight that falls upon it. This means that the sun is powerless to melt clean snow. And when ... on a spring day because of the sun's heat. It melts because of the warm air from the sea.
Description : Water is not suitable as a calorimetric substance because it – (1) has high specific heat (2) is a good conductor (3) has high boiling point (4) low latent heat of vaporization
Last Answer : (1) has high specific heat Explanation: The specific heat of water is higher than all other common substances. Hence, water is used for heating purposes (as in hot water bottles) and for cooling ... the liquids, mercury has the lowest specific heat due to which it is used as a thermometric liquid.
Description : Water is not suitable as a calorimetric substance because it : (1) has high specific heat (2) is a good conductor (3) has high boiling point (4) low latent heat of vapourization
Last Answer : has high specific heat
Description : The snow on the mountains does NOT melt all at once when it is heated by the sun because: (1) it becomes very hard (2) it reflects most of the heat from the sun (3) it has a low specific heat capacity (4) it has a high latent heat of fusion
Last Answer : it reflects most of the heat from the sun
Description : Pick out the undesirable property for a solvent meant for dewaxing of lube oil. (A) Complete miscibility with oil (B) High solubility of wax in the solvent (C) Both (A) and (B) (D) Neither (A) nor (B)
Description : Which of the following is an undesirable property of slag produced during the Pyrometallurgical method of metal extraction from its ore? (A) High fusibility & fluidity (B) High thermal conductivity (C) Low density (D) High chemical activity
Last Answer : B) High thermal conductivity
Description : Heat in BTU necessary to increase the temperature of 1 lb of gas and its accompanying vapour by 1°F is called the (A) Latent heat (B) Humid heat (C) Specific heat (D) Sensible heat
Last Answer : (C) Specific heat
Description : A good solvent used for absorption should not have very high (A) Viscosity (B) Vapor pressure (C) Freezing point (D) All (A), (B) & (C)
Description : Pick out the additive property of lube oil out of following. (A) °API gravity (B) Specific gravity (C) Viscosity (D) Flashpoint
Last Answer : (A) °API gravity
Description : If the specific heats of a gas and a vapor are 0.2KJ/Kg.°K and 1.5 KJ/Kg.°K respectively, and the humidity is 0.01; the humid heat in KJ/°Kg. is (A) 0.31 (B) 0.107 (C) 0.017 (D) 0.215
Last Answer : (D) 0.215
Description : Specific/molar Gibbs free energy for a pure substance does not change during (A) Sublimation (B) Vaporisation (C) Melting (D) Either (A), (B) or (C)
Last Answer : (D) Either (A), (B) or (C)
Description : Steam at 100°C causes more severe burns than water at 100° C because – (1) steam has no specific heat capacity (2) steam has latent heat of vaporization (3) water has no specific heat capacity (4) water has latent heat of fusion
Last Answer : (2) steam has latent heat of vaporization Explanation: It is because steam releases its latent heat as it condenses, which is substantial. The heat of vaporization of steam is over 2000 J per gram. And when it releases that it's then 100 degree water, the same as boiling water.
Description : Heat stored in water vapour is – (1) specific heat (2) latent heat (3) absolute heat (4) relative heat
Last Answer : (2) latent heat Explanation: Latent heat is the heat released or absorbed by a body or a thermodynamic system during a process that occurs without a change in temperature. A typical example is a ... the boiling of water. So water vapor which is the end product of evaporated water has latent heat.
Description : What refers to the heat needed to change the temperature of the substances without changing its phases? a. Latent heat b. Sensible heat c. Specific heat d. entropy
Last Answer : Sensible heat