160 Important Heat And Mass Transfer MCQ Question and Answer | PDF Free Download
1.The most commonly used method for the design of duct size is the
- AVelocity reduction method
- BEqual friction method
- CStatic regains method
- DDual or double method
2.Thermal diffusivity is a
- AFunction of temperature
- BPhysical property of a substance
- CDimensionless parameter
- DAll of these
3.Film coefficient is defined as Inside diameter of tube
- AEquivalent thickness of film
- BThermal conductivity Equivalent thickness of film Specific heat × Viscosity
- CThermal conductivity Molecular diffusivity of momentum Thermal diffusivity
- DFilm coefficient × Inside diameter Thermal conductivity
4.The amount of radiation mainly depends upon the
- ANature of the body
- BTemperature of the body
- CType of surface of the body
- DAll of these
5.The emissive power of a body depends upon its
- ATemperature
- BWave length
- CPhysical nature
- DAll of the above
6.When heat is transferred from one particle of hot body to another by actual motion of the heated particles, it is referred to as heat transfer by
- AConduction
- BConvection
- CRadiation
- DConduction and convection
7.Sensible heat is the heat required to
- AChange vapour into liquid
- BChange liquid into vapour
- CIncrease the temperature of a liquid of vapour
- DConvert water into steam and superheat it
8.Total heat is the heat required to
- AChange vapour into liquid
- BChange liquid into vapour
- CIncrease the temperature of a liquid or vapour
- DConvert water into steam and superheat it
9.A steam pipe is to be insulated by two insulating materials put over each other. For best results
- ABetter insulation should be put over pipe and better one over it
- BInferior insulation should be put over pipe and better one over it
- CBoth may be put in any order
- DBoth may be put in any order
10.The value of Prandtl number for air is about
- A0.1
- B0.3
- C0.7
- D1.7
11.The amount of heat flow through a body by conduction is
- ADirectly proportional to the surface area of the body
- BDirectly proportional to the temperature difference on the two faces of the body
- CDependent upon the material of the body
- DAll of the above
12.The radiation emitted by a black body is known as
- ABlack radiation
- BFull radiation
- CTotal radiation
- DAll of these
13.Heat is transferred by all three modes of transfer, viz. conduction, convection and radiation in
- AElectric heater
- BSteam condenser
- CBoiler
- DRefrigerator condenser coils
14.The heat is transferred by conduction, convection and radiation in
- AMelting of ice
- BBoiler furnaces
- CCondensation of steam in condenser
- DNone of these
15.All radiations in a black body are
- AReflected
- BRefracted
- CTransmitted
- DAbsorbed
16.Depending on the radiating properties, a body will be black when (Where a = absorptivity, p = reflectivity, X = transmissivity.)
- AP = 0, x = 0 and a = 1
- BP= 1, T = 0 and a = 0
- CP = 0, x = 1 and a = 0
- DX = 0, a + p = 0
17.Total emissivity of polished silver compared to black body is
- ASame
- BHigher
- CMore or less same
- DVery much lower
18.A composite slab has two layers of different materials with thermal conductivities k₁ and k₂. If each layer has the same thickness, then the equivalent thermal conductivity of the slab will be
- Ak₁ k₂
- B(k₁ + k₂)
- C(k₁ + k₂)/ k₁ k₂
- D2 k₁ k₂/ (k₁ + k₂)
19.According to Dalton's law of partial pressures, (where pb = Barometric pressure, pa = Partial pressure of dry air, and pv = Partial pressure of water vapour)
- APb = pa – pv
- BPb = pa + pv
- CPb = pa × pv
- DPb = pa/pv
20.Conduction is a process of heat transfer
- AFrom one particle of the body to another without the actual motion of the particles
- BFrom one particle of the body to another by the actual motion of the heated particles
- CFrom a hot body to a cold body, in a straight line, without affecting the intervening medium
- DNone of the above