MCQOPTIONS
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MCQOPTIONS
This section includes 640 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is |
| A. | 0.2 |
| B. | 0.4 |
| C. | 0.6 |
| D. | 0.8 |
| Answer» D. 0.8 | |
| 152. |
Latent heat absorbed by 1 lb of water at 212°F, when it is changed to steam at 212°F, may be around __________ BTU.$ |
| A. | 180 |
| B. | 970 |
| C. | 3.97 |
| D. | none of these |
| Answer» B. 970 | |
| 153. |
__________ chart is known as transient heat conduction chart. |
| A. | Dirhing's |
| B. | Heisler's |
| C. | Mollier's |
| D. | Cox |
| Answer» B. Heisler's | |
| 154. |
Multiple effect evaporation is generally recommended, when the |
| A. | large scale evaporation of liquor is needed. |
| B. | corrosive liquids are to be concentrated. |
| C. | fuel is cheaply available. |
| D. | evaporation on small scale is to be done. |
| Answer» B. corrosive liquids are to be concentrated. | |
| 155. |
In case of a vertical tube evaporator, with increase in the liquor level, the __________ is increased. |
| A. | velocity of circulation |
| B. | liquor-film co-efficient |
| C. | both (a) and (b) |
| D. | neither (a) and (b) |
| Answer» E. | |
| 156. |
Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m2 .°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the$ |
| A. | higher condensing film co-efficient is desired. |
| B. | condensate is corrosive in nature. |
| C. | lower pressure drop through the exchanger is desired. |
| D. | temperature of the incoming vapor is very high. |
| Answer» C. lower pressure drop through the exchanger is desired. | |
| 157. |
In a shell and tube heat exchanger, floating head is used for |
| A. | large temperature differentials. |
| B. | high heat transfer co-efficient. |
| C. | low pressure drop. |
| D. | less corrosion of tubes. |
| Answer» B. high heat transfer co-efficient. | |
| 158. |
Water always boils when its |
| A. | temperature reaches 100° C. |
| B. | vapour pressure equals 76 cm of Hg. |
| C. | saturated vapour pressure equals the external pressure on its surface. |
| D. | saturated vapour pressure is less than the atmospheric pressure. |
| Answer» D. saturated vapour pressure is less than the atmospheric pressure. | |
| 159. |
Vacuum is generally maintained in the vapour space of an evaporator mainly to |
| A. | get economical temperature difference by using moderate pressure steam. |
| B. | facilitate forward feeding in multiple effect evaporation. |
| C. | concentrate heat sensitive materials. |
| D. | achieve very high concentration of the final product. |
| Answer» B. facilitate forward feeding in multiple effect evaporation. | |
| 160. |
An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a |
| A. | boiler |
| B. | heat exchanger |
| C. | recuperator |
| D. | regenerator |
| Answer» C. recuperator | |
| 161. |
A multiple effect evaporator has a capacity to process 4000 kg of solid caustic soda per day, when it is concentrating from 10% to 25% solids. The water evaporated in kg per day is |
| A. | 6000 |
| B. | 24000 |
| C. | 60000 |
| D. | 48000 |
| Answer» C. 60000 | |
| 162. |
Terminal point temperature differences between fluids in case of a heat exchanger is termed as |
| A. | approach. |
| B. | log mean temperature difference. |
| C. | arithmetic mean temperature difference. |
| D. | geometric mean temperature difference. |
| Answer» B. log mean temperature difference. | |
| 163. |
In counter flow compared to parallel flow, |
| A. | LMTD is greater. |
| B. | less surface area is required for a given heat transfer rate. |
| C. | both (a) and (b). |
| D. | more surface area is required for a given heat transfer rate. |
| Answer» D. more surface area is required for a given heat transfer rate. | |
| 164. |
Stefan-Boltzman law applies to __________ body. |
| A. | black |
| B. | white |
| C. | grey |
| D. | any colour |
| Answer» B. white | |
| 165. |
The radiation heat flux from a heating element at a temperature of 800°C, in a furnace maintained at 300°C is 8 kW/m2. The flux, when the element temperature is increased to 1000°C for the same furnace temperature is$ |
| A. | 11.2 kW/m2 |
| B. | 12.0 kW/m2 |
| C. | 14.6 kW/m2 |
| D. | 16.5 kW/m2 |
| Answer» E. | |
| 166. |
Steam traps are provided in steam carrying pipelines to |
| A. | condense steam. |
| B. | release excess steam pressure by bleeding steam. |
| C. | remove condensate and inert gases. |
| D. | none of these. |
| Answer» D. none of these. | |
| 167. |
Log mean temperature difference (LMTD) cannot be used, if |
| A. | heat transfer co-efficient over the entire heat exchanger is not constant. |
| B. | there exists an unsteady state. |
| C. | the heat capacity is not constant and there is a phase change. |
| D. | none of these. |
| Answer» E. | |
| 168. |
Which of the following is not concerned with the heat transfer? |
| A. | Brinkman number |
| B. | Stanton number |
| C. | Schmidt number |
| D. | Peclet number |
| Answer» D. Peclet number | |
| 169. |
Which of the following parameters is increased by use of finned tube in a multipass shell and tube heat exchanger ? |
| A. | Tube side pressure drop and the heat transfer rate. |
| B. | Convective heat transfer co-efficient. |
| C. | Effective tube surface area for convective heat transfer. |
| D. | All (a) (b) and (c). |
| Answer» E. | |
| 170. |
Heat transfer occurs by natural convection because change in temperature causes difference in |
| A. | viscosity |
| B. | density |
| C. | thermal conductivity |
| D. | heat capacity |
| Answer» C. thermal conductivity | |
| 171. |
Prandtl and Reynolds analogy are same, when Prandtl number is |
| A. | 0.5 |
| B. | 1 |
| C. | > 2 |
| D. | 1.5 |
| Answer» C. > 2 | |
| 172. |
For a cold dilute feed to produce thick viscous liquor, backward feeding as compared to forward feeding results in |
| A. | increased economy |
| B. | decreased economy |
| C. | lower capacity |
| D. | no effect on economy |
| Answer» B. decreased economy | |
| 173. |
Dropwise condensation of steam on cooling surface is promoted |
| A. | an oily surface. |
| B. | when both the steam and the tube are clean. |
| C. | only in presence of air. |
| D. | none of these. |
| Answer» B. when both the steam and the tube are clean. | |
| 174. |
For evaporation of viscous solution in a multiple effect evaporator, the prefered feeding scheme is |
| A. | forward |
| B. | backward |
| C. | parallel |
| D. | none of these |
| Answer» C. parallel | |
| 175. |
What is the emissivity of a black body ? |
| A. | 1 |
| B. | 0  |
| C. | 0.9 |
| D. | 0.5 |
| Answer» B. 0¬† | |
| 176. |
Maximum water velocity in tubes of a 1-2 shell and tube heat exchanger may be around __________ metres/second. |
| A. | 1 |
| B. | 10 |
| C. | 20 |
| D. | 30 |
| Answer» B. 10 | |
| 177. |
Value of Nusselt number [Nu = (hD/k)] for the heat transfer by conduction from a droplet or a spherical particle to a surrounding stagnant film is |
| A. | 0.5 |
| B. | 2 |
| C. | 10 |
| D. | 100 |
| Answer» C. 10 | |
| 178. |
If h1 = inner film co-efficient and /h2 = outer film co-efficient, then the overall heat transfer co-efficient is |
| A. | always less than h1 |
| B. | always between h1 and h2 |
| C. | always higher than h2 |
| D. | dependent on metal resistance |
| Answer» C. always higher than h2 | |
| 179. |
A BTU/hr.ft.2 °F is equal to$ |
| A. | 1 kcal/hr. m2°C. |
| B. | 4.88 kcal/hr. m.2°C. |
| C. | 1 kcal/hr. m2.°K. |
| D. | none of these. |
| Answer» C. 1 kcal/hr. m2.¬∞K. | |
| 180. |
Heat exchanger tubes are never made of |
| A. | plain carbon steel |
| B. | stainless steel |
| C. | lead |
| D. | copper |
| Answer» D. copper | |
| 181. |
Heat exchangers operating, when the asymptotic range is reached, |
| A. | provide very large heat transfer co-efficient. |
| B. | results in making part of the heating surface inactive. |
| C. | results in abruptly increased velocity. |
| D. | none of these. |
| Answer» C. results in abruptly increased velocity. | |
| 182. |
Thermal diffusivity of a material |
| A. | has the unit m2 /sec. |
| B. | is defined as K/ρ . Cp. |
| C. | is the ratio of thermal conductivity to thermal capacity. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 183. |
An insulator should have |
| A. | low thermal conductivity. |
| B. | high thermal conductivity. |
| C. | less resistance to heat flow. |
| D. | a porous structure. |
| Answer» B. high thermal conductivity. | |
| 184. |
Boiling point of a solution according to Duhring's rule is a linear function of the __________ of water. |
| A. | boiling point (at the same pressure) |
| B. | viscosity |
| C. | density |
| D. | thermal conductivity |
| Answer» B. viscosity | |
| 185. |
In case of __________ boiling, the liquid temperature is below the saturation temperature and the boiling takes place in the vicinity of the heated surface. |
| A. | nucleate |
| B. | local |
| C. | pool |
| D. | saturated |
| Answer» C. pool | |
| 186. |
While the total emissivity of a perfect black body is unity, the same for a real body is |
| A. | 0 |
| B. | 1 |
| C. | > 1 |
| D. | between 0 and 1 |
| Answer» E. | |
| 187. |
The Stefan-Boltzman constant depends on the |
| A. | medium |
| B. | temperature |
| C. | surface |
| D. | none of these |
| Answer» E. | |
| 188. |
Steam is routed through the tube in case of a __________ evaporator. |
| A. | basket type |
| B. | horizontal tube |
| C. | short tube vertical |
| D. | long tube vertical |
| Answer» C. short tube vertical | |
| 189. |
Economy of an evaporator is influenced by the |
| A. | steam pressure |
| B. | feed temperature |
| C. | number of effect |
| D. | both(b) & (c) |
| Answer» E. | |
| 190. |
Which of the following has maximum thermal conductivity ? |
| A. | Iron |
| B. | Coal |
| C. | Nitrogen |
| D. | Tar |
| Answer» B. Coal | |
| 191. |
The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C-1 respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m-2.°C-1. The rate of heat loss from the outer surface in W.m-2is$ |
| A. | 165.4 |
| B. | 167.5 |
| C. | 172.5 |
| D. | 175 |
| Answer» B. 167.5 | |
| 192. |
A measure of the extent to which viscous heating is important relative to the heat flow resulting from the impressed temperature difference is represented by the __________ number. |
| A. | Condensation |
| B. | Grashoff |
| C. | Stantan |
| D. | Brinkman |
| Answer» E. | |
| 193. |
Nusselt number for full developed, laminar, constant property flow in a pipe at uniform heat flux is |
| A. | 0.72 |
| B. | 4.364 |
| C. | 18 |
| D. | 83 |
| Answer» C. 18 | |
| 194. |
Use of transverse baffles in a shell and tube heat exchanger is done to increase the |
| A. | rate of heat transfer. |
| B. | flow velocity. |
| C. | turbulence of shell side fluid. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 195. |
Value of Prandtl number for water ranges from |
| A. | l to 2 |
| B. | 5 to 10 |
| C. | 100 to 500 |
| D. | 1000 to 2000 |
| Answer» C. 100 to 500 | |
| 196. |
Prandtl number is the reciprocal of |
| A. | Thermal diffusivity/Momentum diffusivity |
| B. | thermal diffusivity x Momentum |
| C. | Thermal diffusivity x Mass diffusivity |
| D. | Mass diffusivity x Momentum diffusivity |
| Answer» B. thermal diffusivity x Momentum | |
| 197. |
The film co-efficient between condensing vapour and metal wall increases with |
| A. | increasing temperature of the vapour. |
| B. | decreasing temperature of the vapour. |
| C. | increasing viscosity of the film of condensate. |
| D. | increasing temperature drop. |
| Answer» B. decreasing temperature of the vapour. | |
| 198. |
Radiation energy is emitted by all the substances, which are above |
| A. | 0°K |
| B. | 0°C |
| C. | 100°C |
| D. | room temperature |
| Answer» B. 0¬∞C | |
| 199. |
An evaporator while concentrating an aqueous solution from 10 to 40% solids evaporates 30000 kg of water. The amount of solids handled by the system in kg is |
| A. | 4000 |
| B. | 9000 |
| C. | 4600 |
| D. | 3000 |
| Answer» B. 9000 | |
| 200. |
With increase in temperature, the thermal conductivity of steel |
| A. | increases |
| B. | decreases |
| C. | remains unchanged |
| D. | increases exponentially |
| Answer» C. remains unchanged | |