The transfer of heat by molecular collision is smallest in solids liquids gases

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Question
The transfer of heat by molecular collision is smallest in
Options
A. solids
B. liquids
C. gases
D. none of these

Correct Answer

gases

Heat Transfer, Refrigeration and Air Conditioning problems

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2. The atmospheric air at dry bulb temperature of 15�C enters a heating coil maintained at 40�C. The air leaves the heating coil at 25�C. The by-pass factor of the heating coil is
Options
A. 0.376
B. 0.4
C. 0.6
D. 0.67

4. In a spray washing system, if the temperature of water is higher than the dry bulb temperature of entering air, then the air is
Options
A. heated and dehumidified
B. heated and humidified
C. cooled and humidified
D. cooled and dehumidified

6. A composite slab has two layers of different materials with thermal conductivities k₁ and k₂. If each layer has the same thickness, then the equivalent thermal conductivity of the slab will be
Options
A. k₁ k₂
B. k₁ + k₂
C.
D.

8. If the energy radiated per second per sq. cm. of the surface for wave lengths lying between ?, and ? + d? is represented by (e?.d?), then e? is called
Options
A. absorptive power
B. emissive power
C. emissivity
D. none of these

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