| 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
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| 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
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| 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
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| 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
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| 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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