# Heat & Mass Transfer MCQ Question with Answer

## Heat & Mass Transfer MCQ with detailed explanation for interview, entrance and competitive exams. Explanation are given for understanding.

Question No : 1
All radiations in a black body are

Reflected
Refracted
Transmitted
Absorbed

Question No : 2
According to Stefan Boltzmann law, the total radiation from a black body per second per unit area is directly proportional to the

Absolute temperature
Square of the absolute temperature
Cube of the absolute temperature
Fourth power of the absolute temperature

Question No : 3
The logarithmic mean temperature difference (tm) is given by (where Δt1 and Δt2 are temperature differences between the hot and cold fluids at entrance and exit)

tm = (Δt1 - Δt2)/ loge (Δt1/Δt2)
tm = loge (Δt1/Δt2)/ (Δt1 - Δt2)
tm = tm = (Δt1 - Δt2) loge (Δt1/Δt2)
tm = loge (Δt1 - Δt2)/ Δt1/Δt2

Question No : 4
According to Newton's law of cooling, the heat transfer from a hot body to a cold body is

Directly proportional to the surface area
Directly proportional to the difference of temperatures between the two bodies
Either (A) or (B)
Both (A) and (B)

Question No : 5
When absorptivity (α) = 1, reflectivity (ρ) = 0 and transmissivity (τ) = 0, then the body is said to be a

Black body
Grey body
Opaque body
White body

Question No : 6
In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by

Convection