3001. Boyles law i.e. pV = constant is applicable to gases under ___________________?
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A. steady change of pressures

B. only small range of pressures

C. all ranges of pressures

D. atmospheric conditions

E. high range of pressures

3002. According to first law of thermodynamics__________________?
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A. total energy of a system remains constant

B. total internal energy of a system during a process remains constant

C. entropy of a system remains constant

D. internal energy, enthalpy and entropy during a process remain constant

E. work done by a system is equal to heat transferred by the system

3003. For reversible adiabatic process, change in entropy is_________________?
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A. negative.

B. zero

C. minimum

D. unpredictable

E. maximum

3004. Reversed joule cycle is called_________________?
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A. Dual cycle

B. Carnot cycle

C. Brayton cycle

D. Rankine cycle

E. Bell Coleman cycle

3005. The statement that molecular weights of all gases occupy the same volume is known as________________?
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A. Daltons law

B. Law of thermodynamics

C. Avogadros hypothesis

D. Joules law

E. Gas law

3006. Carnot cycle efficiency is maximum when______________?
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A. initial temperature is 0K

B. final temperature is 0K

C. final temperature is 0C

D. initial temperature is minimum possible

E. difference between initial and final temperature is 0K

3008. Sensible heat is the heat required to __________________?
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A. change liquid into vapour

B. change vapour into liquid

C. convert saturated steam into dry steam

D. increase the temperature of a liquid of vapour

E. convert water into steam and superheat it

3009. Unit of thermal conductivity in M.K.S. units is ___________________?
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A. kcal-m/hr C

B. kcal/hr m2 C

C. kcal-m/hr m2 C

D. kcal/kg m2 C

E. kcal-m/m2 C

3010. The insulation ability of an insulator with the presence of moisture would_________________?
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A. none of the above

B. may increase/decrease depending on temperature and thickness of insulation

C. decrease

D. increase

E. remain unaffected

3011. Which of the following is a case of steady state heat transfer ___________________?
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A. none of the above

B. all of the above

C. heating of building in winter

D. I.C. engine

E. air preheaters

3013. Film coefficient is defined as Inside diameter of tube________________?
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A. Film coefficient x Inside diameter Thermalconductivity

B. Equivalent thickness of film

C. none of the above

D. Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity

E. Thermal conductivity Equivalent thickness of film Specific heat x Viscocity
3014. Temperature of steam at around 540C can be measured by ____________________?
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A. thermocouple

B. thermometer

C. thermistor

D. thermopile

E. radiatiouv pyrometer

3015. A non-dimensional number generally associated with natural convection heat transfer is________________?
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A. Reynold number

B. Prandtl number

C. Weber number

D. Nusselt number

E. Grashoff number
3016. Thermal diffusivity of a substance is ____________________?
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A. proportional to (k)

B. inversely proportional to k

C. none of the above

D. inversely proportional to k2

E. proportional of thermal conductivity
3019. In heat exchangers, degree of approach is defined as the difference between temperatures of________________?
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A. cold water inlet and outlet

B. hot medium outlet and cold water outlet

C. hot medium inlet and outlet

D. hot medium outlet and cold water inlet

E. none of the above

3021. Emissivity of a white polished body in comparison to a black body is________________?
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A. higher

B. depends upon the shape of body

C. same

D. lower

E. none of the above

3024. Thermal conductivity of water in general with rise in temperature ____________________?
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A. increases

B. decreases

C. remains constant

D. may increase or decrease depending on temperature

E. none of the above

3025. The amount of heat flow through a body by conduction is_______________?
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A. all of the above

B. dependent upon the material of the body

C. directly proportional to the temperature difference on the two faces of the body

D. directly proportional to the surface area of the body

E. inversely proportional to the thickness of the body

3026. In counter flow heat exchangers_________________?
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A. both the fluids at inlet (of heat exchanger where hot fluid enters) are in their coldest state

B. both the fluids at inlet are in their hottest state

C. both the fluids .at exit are in their hottest state

D. one fluid is in hottest state and other in coldest state at inlet

E. any combination is possible depending on design of heat exchanger

3027. Thermal conductivity of a material may be defined as the________________?
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A. heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces

B. quantity of heat flowing in one second through a slab of the material of area one cm square, thickness 1 cm when its faces differ in temperature by 1C

C. quantity of heat flowing in one second through one cm cube of material when opposite faces ^re maintained at a temperature difference of 1C

D. all of the above

E. none of the above

3028. Thermal diffusivity is ____________________?
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A. useful in case of heat transfer by radiation

B. a dimensionless parameter

C. a physical property of the material

D. used as mathematical model

E. function of temperature

3029. Heat flows from one body to other when they have_________________?
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A. different heat contents

B. different temperatures

C. none of the above

D. different specific heat

E. different atomic structure

3030. Thermal conductivity of air with rise in temperature__________________?
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A. remains constant

B. increases

C. may increase or decrease depending on temperature

D. decreases

E. none of the above

3032. Thermal conductivity of non-metallic amorphous solids with decrease in temperature __________________?
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A. unpredictable

B. remains constant

C. decreases

D. may increase or decrease depending on temperature

E. increases

3034. The concept of overall coefficient of heat transfer is used in case of heat transfer by________________?
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A. conduction and convection

B. radiation

C. convection and radiation

D. conduction

E. convection

3035. In heat transfer, conductance equals conductivity (kcal/hr/sqm/C/cm) divided by ________________?
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A. cm (thickness)

B. kcal (heat).

C. C (temperature)

D. sqm (area)

E. hr (time)

3037. LMTD in case of counter flow heat exchanger as compared-to parallel flow heat exchanger is _________________?
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A. same

B. lower

C. depends on temperature conditions

D. higher

E. depends on the area of heat exchanger

3038. Metals are good conductors of heat because________________?
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A. their atoms-are relatively far apart

B. they have high density

C. all of the above

D. their atoms collide frequently

E. they contain free electrons

3039. Heat is transferred by all three modes of transfer, viz, conduction, convection and radiation in _________________?
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A. boiler

B. electric heater

C. steam condenser

D. melting of ice

E. refrigerator condenser coils

3040. Which of the following is the case of heat transfer by radiation ___________________?
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A. heating of building

B. all of the above

C. blast furnace

D. heat received by a person from fireplace

E. cooling of parts in furnace

3041. A steam pipe is to be insulated by two insulating materials put over each other . For best results__________________?
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A. better insulation should be put over pipe and better one over it

B. inferior insulation should be put over pipe and better one over it

C. both may be put in any order

D. whether to put inferior OIL over pipe or the better one would depend on steam temperature

E. unpredictable

3042. Total heat is the heat required to__________________?
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A. convert water into steam and superheat it

B. increase the temperature of a liquid or vapour

C. change liquid into vapour

D. change vapour into liquid

E. convert saturated steam into dry steam

3043. According to Prevost theory of heat exchange ___________________?
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A. all bodies above absolute zero emit radiation

B. it is impossible to transfer heat from low temperature source to t high temperature source

C. rate of heat transfer depends on thermal conductivity and temperature difference

D. heat transfer by radiation requires no medium

E. heat transfer in most of the cases takes place by combination of conduction, convection and radiation

3044. Heat transfer by radiation mainly depends upon___________________?
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A. nature of the body

B. none of the above

C. its temperature

D. kind and extent of its surface

E. all of the above
3046. The time constant of a thermocouple is_______________?
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A. determined by the time taken to reach 100C from 0C

B. none of the above

C. the time taken to attain 63.2% of the value of initial temperature difference

D. the time taken to attain 50% of the value of initial temperature difference

E. the time taken to attain the final temperature to be measured

3047. Cork is a good insulator because it has___________________?
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A. porous body

B. free electrons

C. low density

D. all of the above

E. atoms colliding frequency

3048. Unit of thermal diffusivity is_________________?
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A. kcal/m2 hrC

B. m2/hr

C. m2/hrC

D. kcal/m.hrC

E. kcal/m2 hr

3050. Fouriers law of heat conduction is valid for_________________?
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A. regular surfaces having non-uniform temperature gradients

B. two dimensional cases only

C. one dimensional cases only

D. three dimensional cases only

E. irregular surfaces