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

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

by

1 Answer

Answer :

(B) Nucleate boiling

by

Related questions

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

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Last Answer : (D) 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

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

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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

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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

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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

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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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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

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Last Answer : (B) Pool

Conversion of a substance directly from solid to vapour state is known as (a) Vaporisation (b) Sublimation (c) Decomposition (d) Ionisation

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In sub-cooled boiling, (A) Temperature of the heating surface is less than the boiling point of the liquid (B) Temperature of the heating surface is more than the boiling point of the liquid (C) Bubbles from heating surface are absorbed by the mass of the liquid (D) Very large vapour space is necessary

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Last Answer : (B) Temperature of the heating surface is more than the boiling point of the liquid

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

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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)

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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)

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Last Answer : (D) All (A), (B) and (C)

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 that of vapour phase (B) Vapour phase behaves as an ideal gas (C) Heat of vaporisation is independent of temperature (D) All (A), (B) & (C)

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When a liquid is at its boiling point, no temperature change takes place due to heating. The energy supplied due to heating (a) Is used up to increase the potential energy of the liquid molecules (b) Is used up to increase the kinetic energy of the molecules (c) Is used up to increase the kinetic energy and potential energy of the molecules (d) Is wasted

Description : When a liquid is at its boiling point, no temperature change takes place due to heating. The energy supplied due to heating (a) Is used up to increase the potential energy of the liquid molecules (b ... c) Is used up to increase the kinetic energy and potential energy of the molecules (d) Is wasted

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Steam distillation is not recommended to be used, if the (A) Azeotropic mixture is to be separated and the final product is miscible with water (B) Liquids decompose, if distilled directly at atmospheric pressure (C) Material cannot be distilled by indirect heating even under low pressure, because of the high boiling temperature (D) Material to be distilled is thermally unstable or has the tendency to react with other components associated with it, at the boiling temperature

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Last Answer : (A) Azeotropic mixture is to be separated and the final product is miscible with water

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Last Answer : (A) 3.06 × 10

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

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

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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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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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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 actual temperature drop across the heating surface of an evaporator depends on the (A) Liquid depth over the heating surface (B) Solution being evaporated (C) Pressure difference between the steam chest and the vapor space above the boiling liquid (D) All (A), (B) and (C)

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The propulsion of water into steam drum by extremely rapid, almost explosive boiling of water at the heating surface is called ___________ a) Foaming b) Priming c) Corrosion d) Caustic embrittlement

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Formation of 8-nucleate embryosac by pollen grains is also called as

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