When vaporisation takes place through a blanketting film of gas, the phenomenon is termed as __________ boiling. (A) Pool (B) Nucleate (C) Transition (D) Film

When vaporisation takes place through a blanketting film of gas, the
phenomenon is termed as __________ boiling.
(A) Pool
(B) Nucleate
(C) Transition
(D) Film
by

1 Answer

Answer :

(D) Film
by

Related questions

When vaporisation takes place directly at the heating surface, it is called (A) Film boiling (B) Nucleate boiling (C) Vapour binding (D) None of these

Description : When vaporisation takes place directly at the heating surface, it is called (A) Film boiling (B) Nucleate boiling (C) Vapour binding (D) None of these

Last Answer : (B) Nucleate boiling

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 that of the damp material (C) Ratio of its capacity to economy equals the steam consumption in kg/hr in an evaporator (D) Vaporisation of organic substances in evaporator mostly causes foam formation

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

In case of __________ boiling, the liquid temperature is below the saturation temperature and the boiling takes place in the vicinity of the heated surface. (A) Nucleate (B) Local (C) Pool (D) Saturated

Description : In case of __________ boiling, the liquid temperature is below the saturation temperature and the boiling takes place in the vicinity of the heated surface. (A) Nucleate (B) Local (C) Pool (D) Saturated

Last Answer : (B) Local

Even though heat transfer co-efficient in boiling liquids is large, use of fins is advantageous, when the entire surface is exposed to __________ boiling. (A) Film (B) Nucleate (C) Transition (D) All modes of

Description : Even though heat transfer co-efficient in boiling liquids is large, use of fins is advantageous, when the entire surface is exposed to __________ boiling. (A) Film (B) Nucleate (C) Transition (D) All modes of

Last Answer : Option A

In case of __________ boiling, the bubbles formed on a submerged hot surface get absorbed in the mass of the liquid. (A) Nucleate (B) Pool (C) Low pressure (D) None of these

Description : In case of __________ boiling, the bubbles formed on a submerged hot surface get absorbed in the mass of the liquid. (A) Nucleate (B) Pool (C) Low pressure (D) None of these

Last Answer : (B) Pool

Boiling of milk in an open vessel is an example of __________ boiling. (A) Film (B) Sub-cooled (C) Saturated nucleate (D) None of these

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Last Answer : (A) Film

Pick out the wrong statement about nucleate boiling. (A) Bubble generation is by expansion of entrapped gas/vapour at small cavities in the surface (B) Surface temperature is greater than the saturation temperature of the liquid (C) Heat transfer from the surface of the liquid is less than that in film boiling (D) The temperature is less than that of film boiling

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Last Answer : (D) The temperature is less than that of film boiling

Heat evolved/absorbed during conversion of a substance from one allotropic form to another is termed as the heat of (A) Fusion (B) Vaporisation (C) Transition (D) None of these

Description : Heat evolved/absorbed during conversion of a substance from one allotropic form to another is termed as the heat of (A) Fusion (B) Vaporisation (C) Transition (D) None of these

Last Answer : (C) Transition

Absorption/evolution of heat during conversion of a substance from one allotropic form to another is termed as the heat of (A) Sublimation (B) Fusion (C) Transition (D) Vaporisation

Description : Absorption/evolution of heat during conversion of a substance from one allotropic form to another is termed as the heat of (A) Sublimation (B) Fusion (C) Transition (D) Vaporisation

Last Answer : C) Transition

Pick out the wrong statement. (A) 'Solvates' are chemical compounds formed by solute with their solvents. When water is the solvent, then it is called a 'hydrate' (B) In heat exchanger calculations (Δt) weighted is used in place of Δt, when it involves more than one sequence of heating or cooling i.e., desuperheating & condensation or condensation & sub-cooling (C) Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted (D) In case of short tube vertical evaporators, area of central downtake is about 50 to 100% of the total tube cross-sectional area

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Last Answer : (C) Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted

Pick out the wrong statement. (A) In case of heat transfer by purely forced convection, GR /Re 2 ≤ 1 (B) The equivalent diameter of heat transfer for a duct of square cross￾section (having each side as 'x') is equal to 4x (C) Distillation process is not the same as evaporation (D) The effectiveness of nucleate boiling depends basically on the ease with which the bubbles are formed and detached from the heating surface

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Nucleate boiling is promoted (A) On polished surfaces (B) On rough surfaces (C) In the absence of agitation (D) None of these

Description : Nucleate boiling is promoted (A) On polished surfaces (B) On rough surfaces (C) In the absence of agitation (D) None of these

Last Answer : (B) On rough surfaces

The burnout heat flux in the nucleate boiling regime is not a function of the (A) Liquid density (B) Vapour density (C) Temperature difference (D) Heat of evaporation

Description : The burnout heat flux in the nucleate boiling regime is not a function of the (A) Liquid density (B) Vapour density (C) Temperature difference (D) Heat of evaporation

Last Answer : (B) Vapour density

At normal boiling point, molar entropy of vaporisation is __________ Joule/K°.mole. (A) 72 (B) 92 (C) 142 (D) 192

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Last Answer : (B) 92

Entropy change of the reaction, H2O (liquid) → H2O (gas), is termed as the enthalpy of (A) Solution (B) Vaporisation (C) Formation (D) Sublimation

Description : Entropy change of the reaction, H2O (liquid) → H2O (gas), is termed as the enthalpy of (A) Solution (B) Vaporisation (C) Formation (D) Sublimation

Last Answer : (B) Vaporisation

Fire in fuel gas pipelines is extinguished most effectively by (A) Spraying water (B) Blanketting the area with nitrogen atmosphere (C) Fire fighting foam (D) None of these

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Last Answer : Option B

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 constituents of the mixture (C) Have high latent heat of vaporisation (D) Have high viscosity to provide high tray efficiency

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

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 vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is (A) 3.06 × 10 5 (B) 6.12 × 10 5 (C) 7.24 × 10 5 (D) 9.08 × 10

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

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

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When a bottle of scent is kept open in a corner of a room its odour is felt in all parts of the room. This is clue to the phenomenon of – (1) evaporation (2) vaporisation (3) diffusion (4) sublimation

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When a bottle of scent is kept open in a corner of a room its odour is felt in all parts of the room. This is due to the phenomenon of : (1) evaporation (2) vaporisation (3) diffusion (4) sublimation

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Last Answer : diffusion

The transition temperature at which all the ferromagnetic materials become paramagnetic materials is termed as the 'Curie temperature'. Its value for cobalt is __________ °C. (A) 768 (B) 1127 (C) 1359 (D) 1480

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The stress at which extension of the material takes place more rapidly as compared to the increase in load is termed as the __________ point of the material. (A) Elastic (B) Ultimate (C) Yielding (D) Breaking

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Calculate the enthalpy of vaporisation per mole for ethanol. Given `DeltaS = 109.8 J K^(-1) mol^(-1)` and boiling point of ethanol is `78.5^(@)`.

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The phenomenon occuring during pumping of a liquid solution containing dissolved gases, which may come out of the solution giving rise to gas pockets, is termed as (A) Evaporation (B) Cavitation (C) Sublimation (D) Stripping

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When larger particles e.g., grains are subjected to fluidisation, the corresponding bed produced is termed as the __________ bed. (A) Spouted (B) Sluggish (C) Boiling (D) Teeter

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Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction?(A) Ash resistance (B) Gas film and pore surface diffusion resistances for reactants (C) Surface phenomenon resistance (D) Gas film and pore surface diffusion resistances for products

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Last Answer : (A) Ash resistance

Film boiling occurs at __________ pressure. (A) Atmospheric (B) Sub-atmospheric (C) Negative (D) Very high

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Humidity chart is useful for the solution of problems concerning condensation, vaporisation and air conditioning. At a given dry bulb temperature, value of humidity obtained from the humidity chart directly, is in terms of __________ humidity. (A) Molal (B) Relative (C) Percentage (D) None of these

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High __________ is an undesirable property for a good refrigerant. (A) Specific heat (B) Latent heat of vaporisation (C) Viscosity (D) Specific vapor volume

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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

A superconductor, during its transition to the superconducting state, expels a magnetic field. After which German physicist is this phenomenon which causes a magnet to levitate above a superconductor named?

Description : A superconductor, during its transition to the superconducting state, expels a magnetic field. After which German physicist is this phenomenon which causes a magnet to levitate above a superconductor named?

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Pick out the wrong statement. (A) Heat transfer from a hot body to cold body by the emission of heat waves is called radiation (B) Filmwise condensation takes place on non-wettable surfaces (C) The boiling point of a solution is affected by liquid head as well as boiling point elevation (D) None of these

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Last Answer : (B) Filmwise condensation takes place on non-wettable surfaces

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 vaporisation is constant (C) Volume in the liquid state is negligible compared with that in the vapour state (D) All (A), (B) and (C)

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)

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Which of the following is not a reversible process? (A) Expansion of an ideal gas against constant pressure (B) Atmospheric pressure vaporisation of water at 100°C (C) Solution of NaCl in water at 50°C (D) None of these

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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

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Last Answer : (A) d ln p/dt = Hvap/RT2

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Description : (A) `S_(N^(2))` reactioin takes place in single step. (R) `S_(N^(2))` reaction involves transition state intermediate.

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In the free convection regime of pool boiling, the heat flux is proportional to (A) Δt 1/2 (B) Δt 2 (C) Δt 5/4 (D) Δt

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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 proportional to the number of times the fluid crosses the bundle between baffles (C) Propagation velocity for travel of heat radiation through vacuum is equal to the velocity of the light (D) The amount of heat involved in the condensation or vaporisation of 1 kg of a fluid is the same

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In turbulent flow, a rough pipe has the same friction factor as a smooth pipe (A) In the zone of complete turbulence (B) When the roughness projections are much smaller than the thickness of the laminar film (C) Everywhere in the transition zone (D) When the friction factor is independent of the Reynold's number

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Why does the phenomenon of ‘trade winds’ takes place? -Do You Know?

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Last Answer : answer:

Why does the phenomenon of ‘trade winds’ takes place?

Description : Why does the phenomenon of ‘trade winds’ takes place?

Last Answer : Due to convection of heat

When two species of different genealogy come to resemble each other as a result of adaptation, the phenomenon is termed

Description : When two species of different genealogy come to resemble each other as a result of adaptation, the phenomenon is termed

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The phenomenon of inhibition of glycolysis by O2 is termed as (A) Red drop (B) Pasteur effect (C) Michaelis effect (D) Fischer’s effect

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