With increase in porosity, the thermal conductivity of a solid substance__________________?

Related Mcqs:

1. For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally ?

   A. Decreases
   B. Increases
   C. Remains unchanged
   D. Increases exponentially

2. The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K0 + at, where, K is the thermal conductivity and T is the temperature (in °K). The units of ‘a’ in SI system will be________________?

   A. W/m.k
   B. W/m
   C. W/m.k2
   D. None, ‘a’ is just a number

3. 200 kg of solids (on dry basis) is subjected to a drying process for a period of 5000 seconds. The drying occurs in the constant rate period with the drying rate as, Nc = 0.5 × 10-3 kg/m2.s. The initial moisture content of the solid is 0.2 kg moisture/kg dry solid. The interfacial area available for drying is 4 m2/1000 kg of dry solid. The moisture content at the end of the drying period is (in kg moisture/kg dry solid)?

   A. 0.5
   B. 0.05
   C. 0.1
   D. 0.15

4. Thermal conductivity of a conducting solid material depends upon its_______________?

   A. Temperature
   B. Porosity
   C. Both A. & B.
   D. Neither A. nor B.

5. _____________ equation relates the thermal conductivity of a solid to its temperature ?

   A. Antoine
   B. Kopp’s
   C. Lee’s
   D. Kistyakowsky

6. With increase in temperature, the thermal conductivity of most liquids_________________?

   A. Increases
   B. Decreases
   C. Remain same
   D. First increases upto a certain temperature and then becomes constant

7. With increase in temperature, the thermal conductivity of fresh lubricating oil ___________________?

   A. Increases
   B. Decreases
   C. Remains unchanged
   D. May increase or decrease; depends on its composition

8. With increase in temperature, the thermal conductivity of a gas ___________________?

   A. Increases
   B. Decreases
   C. Remain same
   D. May increase or decrease depending on the type of gas

9. With increase in temperature, the thermal conductivity of non-metallic amorphous solids_________________?

   A. Decreases
   B. Increases
   C. Remain constant
   D. First decreases upto certain temperature and then increases

10. With increase in temperature, the thermal conductivity of steel___________________?

    A. Increases
    B. Decreases
    C. Remains unchanged
    D. Increases exponentially