Heat and Mass Transfer
Depending on the radiating properties, a body will be black when(Where a = absorptivity, p = reflectivity, X = transmissivity.)

X = 0, a + p = 0
P = 0, x = 0 and a = 1
P = 0, x = 1 and a = 0
P= 1, T = 0 and a = 0

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)

(dx/dT)
(dT/dx)
k.
k. (dT/dx)
k. (dx/dT)
k.

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
Thermal conductivity of a material may be defined as the

Quantity of heat flowing in one second through one cm cube of material when opposite faces are maintained at a temperature difference of 1°C
Heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces
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 1°C
All of these

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
Kirchhoff's law states that

The wave length corresponding to the maximum energy is proportional to the absolute temperature
The total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature
None of these
The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body

ANSWER DOWNLOAD EXAMIANS APP
MORE MCQ ON Heat and Mass Transfer