Chemical Engineering Basics - Study Mode
[#911] First empirical temperature scale conceived is the __________ temperature scale.
Correct Answer
(C) Farenhite
[#912] If a heat transfer surface is pock-marked with a number of cavities, then as compared to a smooth surface the heat transfer by __________ will not increase.
Correct Answer
(C) Radiation
Explanation
Solution: Radiation: The heat transfer by radiation is independent of surface texture (like cavities or pock-marks) and relies on the emissivity and temperature of the surface. Hence, the heat transfer by radiation does not increase due to the presence of cavities. Convection: Cavities on a heat transfer surface can enhance convection by disturbing the boundary layer, promoting turbulence and fluid mixing. This increases the rate of convective heat transfer. Nucleate Boiling: Cavities act as nucleation sites, facilitating bubble formation and improving heat transfer during boiling. Conduction: Surface irregularities could affect conduction slightly but are less significant in comparison to the other modes of heat transfer.
Thus, Option C: Radiation is the correct answer because it remains unaffected, while other modes of heat transfer may increase with a pock-marked surface.
[#913] Materials having resistivity ranging from 1 to 100 ohm. cm is termed as
Correct Answer
(C) Semi-conductor
[#914] Alloys having more than 80% copper are generally more
Correct Answer
(B) Corrosion resistant
[#915] As per international norms, the maximum permissible value of noise level in the industrial environment is __________ decibels as measured at a distance of 1.5 metres from the source of noise.
Correct Answer
(B) 85