Cork is a good insulator because it has___________________?

A. Free electrons
B. Atoms colliding frequency
C. Low density
D. Porous body

Thermal conductivity of air at room temperature in kcal/m hr °C is of the order of__________________?

A. 0.002
B. 0.02
C. 0.01
D. 0.1

Thermal conductivity of air with rise in temperature__________________?

A. Increases
B. Decreases
C. Remains constant
D. May increase or decrease depending on temperature

Total heat is the heat required to__________________?

A. Change vapour into liquid
B. Change liquid into vapour
C. Increase the temperature of a liquid or vapour
D. Convert water into steam and superheat it

Thermal conductivity of water at 20°C is of the order of_____________________?

A. 0.1
B. 0.23
C. 0.42
D. 0.51

The time constant of a thermocouple is_______________?

A. The time taken to attain the final temperature to be measured
B. The time taken to attain 50% of the value of initial temperature difference
C. The time taken to attain 63.2% of the value of initial temperature difference
D. Determined by the time taken to reach 100°c from 0°c

In heat transfer, conductance equals conductivity (kcal/hr/sqm/°C/cm) divided by ________________?

A. Hr (time)
B. Sqm (area)
C. °c (temperature)
D. Cm (thickness)

Which of the following is expected to have highest thermal conductivity_______________?

A. Steam
B. Solid ice
C. Melting ice
D. Water

Thermal conductivity of a material may be defined as the________________?

A. Quantity of heat flowing in one second through one cm cube of material when opposite faces ^re maintained at a temperature difference of 1°c
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 1°c
C. Heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces
D. All of the above

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

A. electric heater
B. steam condenser
C. melting of ice
D. refrigerator condenser coils