The value of Prandtl number for air is about _______________________?

A. 0.1
B. 0.3
C. 0.7
D. 1.7

Total emissivity of polished silver compared to black body is___________________?

A. Same
B. Higher
C. More or less same
D. Very much lower

The value of the wavelength for maximum emissive power is given by ___________________?

A. Wien’s law
B. Planck’s law
C. Stefan’s law
D. Fourier’s law

The unit of overall coefficient of heat transfer is___________________?

A. Kcal/m2
B. Kcal/hr °c
C. Kcal/m2 hr °c
D. Kacl/m hr °c

All radiations in a black body are___________________?

A. Reflected
B. Refracted
C. Transmitted
D. Absorbed

According to Kirchoff’s law, the ratio of emissive power to absorptivity for all bodies is equal to the emissive power of a _________________?

A. Grey body
B. Brilliant white polished body
C. Red hot body
D. Black body

Joule sec is the unit of_________________?

A. Universal gas constant
B. Kinematic viscosity
C. Thermal conductivity
D. Planck’s constant

The concept of overall coefficient of heat transfer is used in case of heat transfer by________________?

A. Conduction
B. Convection
C. Radiation
D. Conduction and convection

In counter flow heat exchangers_________________?

A. Both the fluids at inlet (of heat ex¬changer where hot fluid enters) are in their coldest state
B. Both the fluids at inlet are in their hot¬test state
C. Both the fluids .at exit are in their hottest state
D. One fluid is in hottest state and other in coldest state at inlet

Fourier’s law of heat conduction is valid for_________________?

A. One dimensional cases only
B. Two dimensional cases only
C. Three dimensional cases only
D. Regular surfaces having non-uniform temperature gradients