MCQOPTIONS
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MCQOPTIONS
This section includes 71 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The initial value (t=0) of the unit step response of the transfer function [(s 1)/(2s 1)] is |
| A. | 01-02-2015 |
| B. | 0 |
| C. | 2 |
| D. | 1 |
| Answer» B. 0 | |
| 2. |
Nichol\'s chart deals with |
| A. | R. vs. phase lag of second order. |
| B. | R. vs. phase lag of first order. |
| C. | frequency response values of controllers |
| D. | closed loop values vs. open loop values. |
| Answer» E. | |
| 3. |
Mercury thermometer is commonly used for low temperature measruement. The freezing point and boiling point of mercury are respectively __________ °C. |
| A. | - 39 and 350 |
| B. | - 51 and 439 |
| C. | - 79 and 395 |
| D. | - 10 and 425 |
| Answer» B. - 51 and 439 | |
| 4. |
Ordinary mercury in glass thermometer is used for measuring temperature upto 120°C. However, for measuring higher temperature upto __________ °C, thermometer is made by filling nitrogen under pressure above the mercury, which stops the evaporation of mercury and reduces the chance of broken thread of mercury. |
| A. | 250 |
| B. | 350 |
| C. | 550 |
| D. | 700 |
| Answer» D. 700 | |
| 5. |
Temperature of molten pig iron (1450°C) and molten slag (1500°C) flowing out of a blast furnace is measured by a/an |
| A. | chromel-alumel thermocouple |
| B. | optical pyrometer |
| C. | radiation pyrometer |
| D. | either (b) or (c) |
| Answer» E. | |
| 6. |
A system with transfer function is of __________ order. |
| A. | zero |
| B. | 1st |
| C. | 2nd |
| D. | 3rd |
| Answer» C. 2nd | |
| 7. |
For the time domain function f ( t ) = t , the Laplace transform of is given by |
| A. | 1/2 S 3 |
| B. | 2/ S 3 |
| C. | 1/ S 3 |
| D. | 2/ S 2 |
| Answer» D. 2/ S 2 | |
| 8. |
Normal mercury thermometer can be used to measure a temperature of about 300°C. However, its maximum temperature measurement range can be increased upto about 500°C by |
| A. | filling nitrogen under pressure in the stem. |
| B. | increasing the diameter of the tube. |
| C. | using steel tube in place of glass tube. |
| D. | accounting for the tube expansion. |
| Answer» B. increasing the diameter of the tube. | |
| 9. |
Conversion formula for converting amplitude ratio ( AR ) into decibels is |
| A. | Decibel = 20 log 10 ( AR ) |
| B. | Decibel = 20 log e ( AR ) |
| C. | Decibel = 20 log 10 ( AR ) 0.5 |
| D. | Decibel = 20 log e ( AR ) 0.5 |
| Answer» B. Decibel = 20 log e ( AR ) | |
| 10. |
Which of the following can measure temperatures in the range of - 20 to 300°C ? |
| A. | Mercury in glass thermometer |
| B. | Vapor pressure thermometer |
| C. | Resistance thermometer |
| D. | None of these. |
| Answer» E. | |
| 11. |
The root locus plot of the roots of the characteristics equation of a closed loop system having the open loop transfer function will have a definite num-ber of loci for variation of K from 0 to ?. The number of loci is |
| A. | 1 |
| B. | 3 |
| C. | 4 |
| D. | 2 |
| Answer» C. 4 | |
| 12. |
A control system has the following transfer function The initial value of the corresponding time function is |
| A. | 1 |
| B. | 1/8 |
| C. | 7/8 |
| D. | -1 |
| Answer» B. 1/8 | |
| 13. |
Which of the following thermocouples is incapable of measuring sub-zero (i.e., < 0°C) temperature ? |
| A. | Chromel-alumel |
| B. | Iron-constantan |
| C. | Platinum-platinum + rhodium |
| D. | Copper-constantan |
| Answer» D. Copper-constantan | |
| 14. |
Emf developed by a thermocouple while measuring a temperature of 800°C is about 31 mV. The type of thermocouple used is |
| A. | chromel-alumel |
| B. | iron-constantan |
| C. | platinum-platinum+rhodium |
| D. | none of these. |
| Answer» B. iron-constantan | |
| 15. |
Platinum resistance thermometer can be used upto antimony point which is __________ °C, and is the temperature of equilibrium between solid antimony & liquid antimony at normal atmospheric pressure. |
| A. | 961.93 |
| B. | 630.74 |
| C. | 1064.43 |
| D. | 1261.93 |
| Answer» C. 1064.43 | |
| 16. |
Which of the following is not suitable for measuring the temperature of a red hot object in the range of 800 - 1600°C ? |
| A. | Optical pyrometer |
| B. | Radiation pyrometer |
| C. | Photoelectric pyrometer |
| D. | Thermocouples |
| Answer» E. | |
| 17. |
Which of the following instruments is not used for measuring sub-zero ( |
| A. | Platinum resistance thermometer |
| B. | Mercury in glass thermometer |
| C. | Vapor pressure thermometer |
| D. | Radiation pyrometer |
| Answer» E. | |
| 18. |
Find the ultimate gain and frequency for a proportional controller in the case of a process having the transfer function G p ( s ) = 1/(4 s + 1)(2 s + 1)( s + 1). |
| A. | w = 1/ 14 , K c = 45/7 14 |
| B. | w = 7/6 , K c = 46/3 |
| C. | w = 1, K c = 13 |
| D. | w = 7/8 , K c = 45/4 |
| Answer» C. w = 1, K c = 13 | |
| 19. |
Which of the following thermocouples is capable of measuring a temperature of -50°C? |
| A. | Platinum - platinum + rhodium |
| B. | Chromel - alumel |
| C. | Iron-constantan |
| D. | Copper - constantan |
| Answer» B. Chromel - alumel | |
| 20. |
Temperature measurement range of iron-constantan thermocouple is 0 to 870°C. It can be used to measure sub zero temperature, because at lower temperature |
| A. | emf produced is very low of the order of microvolt. |
| B. | embrittlement of iron occurs. |
| C. | rusting of iron takes place. |
| D. | both (b) and (c). |
| Answer» E. | |
| 21. |
Liquid column manometers are used for measuring the pressure __________ kgf/cm 2 . |
| A. | > 2(gage) |
| B. | < 3 (gage) |
| C. | < 10 (gage) |
| D. | < atmospheric |
| Answer» C. < 10 (gage) | |
| 22. |
Compositional analysis of flue gas coming out of a furnace in respect of O 2 and CO 2 % can be continuously done by a/an |
| A. | orsat apparatus |
| B. | thermal conductivity cell |
| C. | zirconia probe |
| D. | chromatograph |
| Answer» C. zirconia probe | |
| 23. |
Sub-zero temperature (< 0°C) can be measured by a constant volume gas thermometer employing |
| A. | helium |
| B. | nitrogen |
| C. | hydrogen |
| D. | none of these |
| Answer» B. nitrogen | |
| 24. |
Silver point temperature is __________ °C. |
| A. | 760.5 |
| B. | 860.5 |
| C. | 960.5 |
| D. | 1060.5 |
| Answer» D. 1060.5 | |
| 25. |
What is the Laplace transform of impulse input having magnitude ' X ' ? |
| A. | X |
| B. | X 2 |
| C. | 1/ X |
| D. | 1 |
| Answer» E. | |
| 26. |
Block diagram of a simple standard control system is shown below in the figure. Which of the following statement about the above control system is wrong ? |
| A. | The transfer functions of the measuring element and the process is represent by H and G 2 respectively |
| B. | The overall transfer function for the change in load ( X = 0) is given by |
| C. | The overall transfer function for the change in set point ( X 1 = 0) is given by |
| D. | Manipulated variable is represented by C. |
| Answer» E. | |
| 27. |
Photoelectric pyrometers are suitable in the temperature range of __________ °C. |
| A. | 400-1600 |
| B. | 800-1600 |
| C. | 800-2500 |
| D. | 400-1000 |
| Answer» C. 800-2500 | |
| 28. |
Operating range of a temperature measuring instrument is 800 to 1600°C. It could be a/an __________ pyrometer. |
| A. | radiation |
| B. | optical |
| C. | photoelectric |
| D. | none of these |
| Answer» D. none of these | |
| 29. |
Suppose that the gain, time constant and dead time of a process with the following transfer function: G c ( s ) = 10 exp( - 0.1 s )/(0.5 s + 1) are known with a possible error of ± 20% of their values. The largest permissible gain K c of a proportional controller needs to be calculated below taking the values of process gain, time constant and dead time as |
| A. | 8, 0.6, 0.08 |
| B. | 12, 0.6, 0.12 |
| C. | 8, 0.6, 0.12 |
| D. | 12, 0.4, 0.08 |
| Answer» C. 8, 0.6, 0.12 | |
| 30. |
The root locus method, a pole of a transfer function G ( s ) is the value of s for which G ( s ) approaches |
| A. | -1 |
| B. | 0 |
| C. | 1 |
| D. | ? |
| Answer» E. | |
| 31. |
The open loop transfer function of a control system is . This represents |
| A. | a first order system. |
| B. | dead time system. |
| C. | a first order time lag. |
| D. | a second order system. |
| Answer» B. dead time system. | |
| 32. |
A mercury thermometer can not be used to measure the temperature below the freezing point of mercury, which is __________ °C. |
| A. | -38.9 |
| B. | -11.9 |
| C. | -60.9 |
| D. | -80.9 |
| Answer» B. -11.9 | |
| 33. |
Specific conductance is defined as the reciprocal of resistance in ohms of 1c.c. of liquid at a specified temperature. Its value for distilled water is about __________ micro mho/cm 3 . |
| A. | 50 |
| B. | 100 |
| C. | 10 |
| D. | 1 |
| Answer» E. | |
| 34. |
Emf developed by a thermocouple while measuring a temperature of 400°C is 22 mV. The type of thermocouple used is |
| A. | chromel-alumel |
| B. | iron-constantan |
| C. | platinum-rhodium |
| D. | platinum-platinum+rhyodium |
| Answer» C. platinum-rhodium | |
| 35. |
Temperature measurement by optical pyrometer is done above __________ point, which is 1063°C. |
| A. | antimony |
| B. | gold |
| C. | silver |
| D. | nickel |
| Answer» C. silver | |
| 36. |
Number of poles in a system with transfer function is |
| A. | 2 |
| B. | 5 |
| C. | 3 |
| D. | 1 |
| Answer» D. 1 | |
| 37. |
The inverse Laplace transform of the function is |
| A. | 1 + e t |
| B. | 1 - e t |
| C. | 1 + e -t |
| D. | 1 - e -t |
| Answer» E. | |
| 38. |
The offset introduced by proportional controller with gain K c in response of first order system can be reduced by |
| A. | reducing value of K c . |
| B. | introducing integral control. |
| C. | introducing derivative control. |
| D. | none of the above. |
| Answer» C. introducing derivative control. | |
| 39. |
Bourdon gauges are used for measuring pressure (kg/cm 2 ) |
| A. | < atmospheric |
| B. | > 2 (gauge) |
| C. | < 2 (gauge) |
| D. | > 10 (absolute) |
| Answer» C. < 2 (gauge) | |
| 40. |
Mercury thermometer can be used to measure the temperature upto __________ °C. |
| A. | 100 |
| B. | 250 |
| C. | 350 |
| D. | 750 |
| Answer» D. 750 | |
| 41. |
Which of the following thermocouples is the most suitable for measuring a temperature of about 1600°C in an oxidizing atmosphere ? |
| A. | Platinum-platinum + rhodium |
| B. | Iron-constantan |
| C. | Copper-constantan |
| D. | Chromel-alumel |
| Answer» B. Iron-constantan | |
| 42. |
Helium gas constant volume thermometer is suitable for the measurement of a temperature of __________ °C. |
| A. | < 100 |
| B. | < 0 |
| C. | > 0 |
| D. | > 800 |
| Answer» C. > 0 | |
| 43. |
The open loop transfer function of a process is . In the root locus diagram, the poles will be at |
| A. | -1, -4 |
| B. | 1, 4 |
| C. | -2, -3 |
| D. | 2, 3 |
| Answer» D. 2, 3 | |
| 44. |
Water is entering a storage tank at a temperature T 0 and flow rate Q 0 and leaving at a flow rate Q and temperature T . There are negligible heat losses in the tank. The area of cross-section of the tank is A 0 . The model that describes the dynamic variation of temperature of water in the tank with time is given as : |
| A. | Q 0 ( T 0 - T ) = A c . |
| B. | Q 0 T 0 - QT = A c . |
| C. | Q ( T 0 - T ) = A c . |
| D. | Q ( T 0 - T ) = A c . |
| Answer» B. Q 0 T 0 - QT = A c . | |
| 45. |
A constant volume gas thermometer employing __________ is used to measure sub-zero (i.e., < 0° C) temperature. |
| A. | helium |
| B. | hydrogen |
| C. | nitrogen |
| D. | none of these |
| Answer» B. hydrogen | |
| 46. |
The time constant of a unity gain, first order plus time delay process is 5 min. If the phase lag at a frequency of 0.2 rad/min is 60°, then the dead time (in minutes) is |
| A. | 5?/12 |
| B. | ?/6 |
| C. | ?/12 |
| D. | ?/3 |
| Answer» B. ?/6 | |
| 47. |
The unit step response of the transfer function 1/( s 2 + 2 s + 3) |
| A. | has a non-zero slope at the origin. |
| B. | has a damped oscillatory characteristics. |
| C. | is overdamped |
| D. | is unstable |
| Answer» C. is overdamped | |
| 48. |
High temperature of around 2000°C of incandescent gas mantles is measured by a/an |
| A. | specially designed thermocouple. |
| B. | optical pyrometer. |
| C. | radiation pyrometer. |
| D. | none of these. |
| Answer» D. none of these. | |
| 49. |
Nitrogen gas constant volume thermometer is suitable for measuring a temperature of __________ °C. |
| A. | 0-100 |
| B. | < 0 |
| C. | > 100. |
| D. | > 50 |
| Answer» D. > 50 | |
| 50. |
Use of I -control along with P -control facilitates |
| A. | elimination of offset |
| B. | reduction of offset |
| C. | reduction of stability time |
| D. | none of these |
| Answer» B. reduction of offset | |