Top 1000+ Solved Heat Transfer (HT) MCQ Questions Answer
Q. A steel sphere of radius 0.1 m at 400°K is immersed in an oil at 300°K. If the centre of the sphere reaches 350°K in 20 minutes, how long will it take for a 0.05 m radius steel sphere to reach the same temperature (at the centre) under identical conditions? Assume that the conductive heat transfer co-efficient is infinitely large.
a. 5 minutes
b. 10 minutes
c. 20 minutes
d. 40 minutes
Q. Which of the following material has lest value of thermal diffusivity?
a. Aluminium
b. Rubber
c. Lead
d. Mercury
e. Iron
Q. For a opaque body
a. reflectivity = 0
b. absorptivity = reflectivity = 1
c. 37,500 kg
d. absorptivity + reflectivity = 1
e. absorptivity = 0
Q. In which case the value of thermal conductivity drops with rising temperature
a. Methane
b. Benzene
c. Carbondioxide
d. Ammonia
e. None of the above
Q. Which of the following is used as entrainer in acetic acid - water separation?
a. Butyl acetate
b. Methyl alcohol
c. Benzene.
d. Phosphorous
e. Hexane
Q. Which of the following provides maximum contact surface for a liquid vapour system?
a. Wetted wall column
b. Packed tower
c. Sieve plant column
d. Benzene.
e. Bubble cap tower
Q. The lower temperature limit for mercury thermometer is
a. Absolute zero
b. 0?F
c. ? 39?F
d. 0?C
e. 100?C
Q. Cork is a good insulator because
a. It is porous
b. Its density is low
c. It is flexible
d. It can be powdered
e. It can be cast into rolls
Q. The value of thermal conductivity of water at room temperature is expected to be
a. 0.05 kcal/m-hr-?C
b. 0.5 kcal/m-hr-?C
c. 0.001 kcal/m-hr-?C
d. 1.0 kcal/m-hr-?C
e. 1.5 kcal/m-hr-?C
Q. The coefficient of linear expansion of a solid is L. The volume V of a cube of this solid on being heated by 1?C will change by
a. VL
b. VL/3
c. 3 VL
d. 37,500 kg
e. 3L
Q. The unit of thermal conductivity in S.I. units is
a. KJ/m-hr-?K
b. KJ/m-hr?C
c. W/m?K
d. W/m-hr?C
e. W/m-hr-?K
Q. Two rods one of copper and the other of mild steel, both of diameter 20 mm and length 250 mm are coated with a uniform layer of wax all around. These rods are placed vertically in a boiling water bath with 200 mm, length of each rod projecting outside. If the melting point of wax is 10?C, then
a. equal quantity of wax will meet on the two rods
b. more wax will melt on copper rod as compared to mild steel rod
c. 37,500 kg
d. nothing can be predioted as the data is insufficient
e. more wax will melt on mild steel rod as compared to copper rod
Q. Oxygen boils at -183?C, this temperature is
a. ? 215?F
b. ? 361?F
c. ? 227?F
d. ? 329?F
e. ? 398?F
Q. Heat is transferred from an electric bulb mainly by
a. Conduction, convection and radiation.
b. Radiation
c. Convection and conduction
d. Convection
e. Conduction
Q. The average value of thermal conductivity for air at 20?C is about
a. 0.11
b. 0.011
c. 0.022
d. None of the above
e. Nichrome