Insulation of liquid surface can be achieved by _____________ on top of its surface?

Related Mcqs:

1. Upto the critical radius of insulation, added insulation, will____________________?

   A. Increase the heat loss
   B. Decrease heat loss and will have no effect beyond that
   C. Decrease heat flux
   D. Reduce convection heat loss compared to conduction heat less

2. What is the critical radius of insulation (cms) for a metallic cylinder, if the convective heat transfer co-efficient with the ambient atmosphere is 5 W/m2. °K? Thermal conductivity of metal and insulation material are 40 and 0.1 W/m.°K respectively ?

   A. 2
   B. 8
   C. 10
   D. 40

3. Melting point & boiling points of liquid oxygen are respectively – 218.8°C & – 183°C, while the same for liquid nitrogen is – 210°C & – 195.8°C respectively. The difference in melting points of liquid oxygen & liquid nitrogen is not equal to 8.8 ?

   A. °C
   B. °F
   C. °K
   D. °R

4. Maximum heat dissipation occurs from a steel wire (k = 0.5 W/m. k) of 15 mm diameter exposed to air (h = 20W/m2 .k), when the insulation thickness is ________________ mm?

   A. 15
   B. 25
   C. 10
   D. 30

5. Absolute zero, pressure will occur, when the molecular momentum of the system becomes zero. A liquid will cease to exist as liquid at________________?

   A. High vacuum
   B. Zero pressure
   C. 0°K
   D. Earth’s centre

6. The surface tension of a liquid, at critical temperature is____________________?

   A. Indeterminate
   B. Zero
   C. Infinity
   D. Same as that at any other temperature

7. For infinite parallel planes having emissivities ε1 & ε2, the interchange factor for radiation from surface 1 to surface 2 is given by__________________?

   A. (ε1 + ε2)/ε1.ε2
   B. ε1.ε2/(ε1 + ε2 – ε1.ε2)
   C. ε1.ε2
   D. ε1 + ε2

8. Highest cutting speed is achieved by the _______________ tool material ?

   A. High speed steel
   B. Carbide
   C. Cast alloy
   D. Plain carbon steel

9. Density in the solid state is slightly less than that in its liquid state, in case of____________________?

   A. Carbon dioxide
   B. Water
   C. Mercury
   D. None of these

10. The fugacity of liquid water at 298 K is approximately 3171 Pa. Considering the ideal heat of vaporisation as 43723 J/gm.mole, its fugacity at 300 K would be________________?

    A. 3171Pa
    B. 3567Pa
    C. 1.01 × 105Pa
    D. 5000Pa