21. | Mark the matter with least value of thermal conductivity |
a. | Air |
b. | Water |
c. | Ash |
d. | Window glass |
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Answer: (a).Air
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22. | Which one of the following forms of water have the highest value of thermal conductivity? |
a. | Boiling water |
b. | Steam |
c. | Solid ice |
d. | Melting ice |
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Answer: (c).Solid ice
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23. | The average thermal conductivities of water and air conform to the ratio |
a. | 50:1 |
b. | 25:1 |
c. | 5:1 |
d. | 15:1 |
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Answer: (b).25:1
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24. | Identify the very good insulator |
a. | Saw dust |
b. | Cork |
c. | Asbestos sheet |
d. | Glass wool |
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Answer: (d).Glass wool
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25. | Most metals are good conductor of heat because of |
a. | Transport of energy |
b. | Free electrons and frequent collision of atoms |
c. | Lattice defects |
d. | Capacity to absorb energy |
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Answer: (b).Free electrons and frequent collision of atoms
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