MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 830 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. |
A proportional controller with a gain of is used to control a first order process. The offset will increase, if |
| A. | is reduced. |
| B. | is increased. |
| C. | integral control action is introduced. |
| D. | derivative control action is introduced. |
| Answer» B. is increased. | |
| 2. |
The second order system with the transfer function has a damping ratio of |
| A. | 2.0 |
| B. | 0.5 |
| C. | 1.0 |
| D. | 4.0 |
| Answer» C. 1.0 | |
| 3. |
The transfer function for a PID controller is (where, τ is the integral (reset) time and τ is the derivative time.) |
| A. | (1 + τ |
| B. | + τ |
| C. | ). |
| Answer» C. ). | |
| 4. |
For an input forcing function, () = 2, the Laplace transform of this function is |
| A. | 2/ |
| B. | 4/ |
| C. | 2/ |
| D. | 4/ |
| Answer» E. | |
| 5. |
The characteristic equation for the control system with a closed loop transfer function /1 + is given by 1 + = 0. The characteristic equation for the control system |
| A. | depends only upon the open loop transfer function. |
| B. | determines its stability. |
| C. | is the same for set point or load changes. |
| D. | all 'a', 'b' & 'c' |
| Answer» E. | |
| 6. |
The offset introduced by proportional controller with gain in response of first order system can be reduced by |
| A. | reducing value of |
| B. | . |
| C. | introducing integral control. |
| D. | introducing derivative control. |
| E. | none of the above. |
| Answer» C. introducing integral control. | |
| 7. |
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 | |
| 8. |
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 | |
| 9. |
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. | 5π/12 |
| B. | π/6 |
| C. | π/12 |
| D. | π/3 |
| Answer» B. π/6 | |
| 10. |
Which of following error integral is considered as the best criterion in controller settings ? |
| A. | none of these |
| Answer» D. | |
| 11. |
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 | |
| 12. |
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. |
| A. | 50 |
| B. | 100 |
| C. | 10 |
| D. | 1 |
| Answer» E. | |
| 13. |
The root locus method, a pole of a transfer function () is the value of s for which () approaches |
| A. | -1 |
| B. | 0 |
| C. | 1 |
| D. | ∞ |
| Answer» E. | |
| 14. |
Suppose that the gain, time constant and dead time of a process with the following transfer function:() = 10 exp( - 0.1)/(0.5 + 1) are known with a possible error of ± 20% of their values. The largest permissible gain 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 | |
| 15. |
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. | |
| 16. |
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 | |
| 17. |
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 | |
| 18. |
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 | |
| 19. |
In Bode plot, A.R. vs. is plotted on a/an __________ graph paper. |
| A. | log-lag |
| B. | triangular |
| C. | ordinary |
| D. | semi-log |
| Answer» B. triangular | |
| 20. |
A first order system with unity gain and time constant τ is subjected to a sinusoidal input of frequency = 1/τ. The amplitude ratio for this system is |
| A. | 1 |
| B. | 0.5 |
| C. | 1/ |
| D. | 0.25 |
| Answer» D. 0.25 | |
| 21. |
Use of -control along with -control facilitates |
| A. | elimination of offset |
| B. | reduction of offset |
| C. | reduction of stability time |
| D. | none of these |
| Answer» B. reduction of offset | |
| 22. |
The unit step response of the transfer function 1/( + 2 + 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 | |
| 23. |
The calibration data of a thermocouple with its cold junction at 0°C are given below.The hot junction of the thermocouple is placed in a bath at 80°C, while its cold junction is at 20°C. What is the emf of thermocouple ? |
| A. | 3.26 mv |
| B. | 0.80 mv |
| C. | 2.46 mv |
| D. | 2.43 mv |
| Answer» D. 2.43 mv | |
| 24. |
The frequency response of a dynamic element shows a constant magnitude ratio at all frequencies. The element exhibits a negative phase shift at all frequencies. The absolute value of the phase shift increases linearly with frequency. The element has the transfer function |
| A. | e |
| Answer» B. | |
| 25. |
In a closed loop system, the process to be controlled is an integrating process with transfer function l/2. The controller proposed to be used in an integral controller with transfer function 1/. When a step change in set point is applied to such a closed loop system, the controlled variable will exhibit |
| A. | overdamped response. |
| B. | underdamped response. |
| C. | undamped response. |
| D. | unstable response. |
| Answer» C. undamped response. | |
| 26. |
An ideal PID controller has the transfer function . The frequency at which the magnitude ratio of the controller is 1, is |
| A. | 0.5/0.2 |
| B. | 0.2/0.5 |
| C. | 0.2 x 0.5 |
| D. | 1/ |
| Answer» E. | |
| 27. |
The unit step response of the transfer functionreaches its final steady state assymptotically after |
| A. | a monotonic increase. |
| B. | a monotonic decrease. |
| C. | initially increasing and then decreasing. |
| D. | increasing decreasing and then increasing. |
| Answer» B. a monotonic decrease. | |
| 28. |
Liquid argon level in a pressurised storage tank (at 3 kg/cm ) is measured by a/an |
| A. | gage glass |
| B. | external float gage |
| C. | differential pressure gage |
| D. | none of these |
| Answer» D. none of these | |
| 29. |
Transfer functions / for which of the following block diagrams is |
| A. | none of these |
| Answer» B. | |
| 30. |
__________ temperature scale assigns 0° to the 'ice point' and 80° to the 'steam point'. |
| A. | Celcius |
| B. | Rankine |
| C. | Reumur |
| D. | Farenhite |
| Answer» D. Farenhite | |
| 31. |
In a single tank system, the transfer function of __________ to inlet flow rate is 1/+1. |
| A. | outlet flow rate |
| B. | level |
| C. | both (a) & (b) |
| D. | neither (a) nor (b) |
| Answer» B. level | |
| 32. |
Mercury thermometer can be used to measure the temperature upto __________ °C. |
| A. | 100 |
| B. | 250 |
| C. | 350 |
| D. | 750 |
| Answer» D. 750 | |
| 33. |
The transfer function of a process is . If a step change is introduced into the system, then the response will be |
| A. | under damped |
| B. | critically damped |
| C. | over damped |
| D. | none of these |
| Answer» B. critically damped | |
| 34. |
The transfer function of a second order system is |
| A. | none of these |
| Answer» B. | |
| 35. |
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 | |
| 36. |
Bourdon gauges are used for measuring pressure (kg/cm ) |
| A. | < atmospheric |
| B. | > 2 (gauge) |
| C. | < 2 (gauge) |
| D. | > 10 (absolute) |
| Answer» C. < 2 (gauge) | |
| 37. |
Which of the following instruments is not used for measuring sub-zero (<0°) temperatures ? |
| A. | Platinum resistance thermometer |
| B. | Mercury in glass thermometer |
| C. | Vapor pressure thermometer |
| D. | Radiation pyrometer |
| Answer» E. | |
| 38. |
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. | |
| 39. |
The transfer function of a first order system is |
| A. | none of these |
| Answer» B. | |
| 40. |
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 | |
| 41. |
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 | |
| 42. |
Very low pressure is expressed in microns(μ), which is equal to __________ mm of Hg coloumn (absolute) at 0°C. |
| A. | 0.0001 |
| B. | 0.001 |
| C. | 0.01 |
| D. | 0.1 |
| Answer» C. 0.01 | |
| 43. |
Number of poles in a system with transfer function is |
| A. | 2 |
| B. | 5 |
| C. | 3 |
| D. | 1 |
| Answer» D. 1 | |
| 44. |
Temperature measurement by optical pyrometer is done above __________ point, which is 1063°C. |
| A. | antimony |
| B. | gold |
| C. | silver |
| D. | nickel |
| Answer» C. silver | |
| 45. |
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. | |
| 46. |
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 | |
| 47. |
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 | |
| 48. |
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 | |
| 49. |
For the time domain function () = , the Laplace transform of is given by |
| A. | 1/2 |
| B. | 2/ |
| C. | 1/ |
| D. | 2/ |
| Answer» D. 2/ | |
| 50. |
A system with transfer function is of __________ order. |
| A. | zero |
| B. | 1st |
| C. | 2nd |
| D. | 3rd |
| Answer» C. 2nd | |