E-PolyLearning

26. Heat conduction in gases is due to
a. Elastic impact of molecules
b. Movement of electrons
c. EM Waves
d. Mixing of gases
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Answer: (a).Elastic impact of molecules

27. The heat energy propagation due to conduction heat transfer will be minimum for
a. Lead
b. Water
c. Air
d. Copper
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Answer: (c).Air

28. Cork is a good insulator because
a. It is flexible
b. It can be powdered
c. Low density
d. It is porous
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Answer: (d).It is porous

29. Choose the false statement
a. For pure metal thermal conductivity is more
b. Thermal conductivity decreases with increase in the density of the substance
c. Thermal conductivity of dry material is lower than that of damp material
d. Heat treatment causes variation in thermal conductivity
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Answer: (b).Thermal conductivity decreases with increase in the density of the substance

30. What is the thermal conductivity of asphalt in W/m K?
a. 0.064
b. 0.063
c. 0.062
d. 0.061
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Answer: (c).0.062

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