# Heat and Mass Transfer MCQ questions and answers

Heat and Mass Transfer MCQ questions and answers

1- The rate of heat transfer is said to be constant if temperature

(A) decreases

(B) increases

(C) become zero

(D) none of the above

2- Following is critical radius of insulation for spheres

(Where h = convective heat transfer coefficient and k = thermal conductivity)

(A) k/h

(B) k/2h

(C) 2k/h

(D) 3k/h

3- The Nusselt number is a function of

(A) Prandtl number

(B) Grashoff’s number

(C) Prandtl number and Grashoff’s number

(D) Mach number

4- Planck’s law is applicable to

(D) All of the above

5- Thermal conductivity of liquid can be measured by

(A) Lee’s method

(B) Guarded plate method

(C) Plank’s method

(D) All of the above

6- Drop-wise condensation normally occurs for

(A) Coated surface

(B) Oily surface

(C) Rough surface

(D) All of the above

7- Following is the units of Stefan Boltzmann constant

(A) watt / m2 K4

(B) watt / m2 K3

(C) watt / m2 K2

(D) watt / m2 K

8- The critical radius (r) of insulation for cylinder is equal to

(Where h = convective heat transfer coefficient and k = thermal conductivity)

(A) h/k

(B) (k/h)1/2

(C) 2h/k

(D) (2k/h)1/2

9- Following has poor transmissivity

(A) Gases

(B) Solids

(C) Liquids

(D) All of the above

10- Which one of the following has least value of Prandtl number

(A) Brine solution

(B) Liquid metal

(C) Gases

(D) None of the above

11- Heat correction factor is needed in

(A) Multi pass flow

(B) Counter flow

(C) Parallel flow

(D) Cross flow

12- Fourier law of heat conduction is applied to

(A) One dimensional flow

(B) Two dimensional flow

(C) Profile with variable temperature gradient

(D) All of the above

13- Which of the following has poor reflectivity?

(A) Gases

(B) Solids

(C) Liquids

(D) All of the above

14- Following is the unit of Planck’s constant

(A) Joule-sec

(B) Joule/sec

(C) Joule2-sec

(D) Joule-sec2

15- Schmidt number is expressed as

(A) μρ / D

(B) μ / D

(C) μ / ρ

(D) μ / ρD

16- Peclet number is expressed as

(A) Reynolds Number x Prandtl Number

(B) Reynolds Number / Prandtl Number

(C) Prandtl Number / Reynolds Number

(D) None of the above

17- Following dimensionless number is used for convective heat transfer

(A) Biot number

(B) Weber number

(C) Nusselt number

(D) Mach number

18- Buoyant force / Viscous force =

(A) Weber number

(B) Euler number

(C) Schmidt number

(D) Grashoff’s number

19- Grashoff number is used in the study of situations involving

(B) Forced convection

(C) Conduction

(D) Natural convection

20- Kinematic viscosity / Thermal diffusivity =

(A) Mach number

(B) Grashoff’s number

(C) Euler Number

(D) Prandtl number