All Free Chemical Engineering MCQs with Answers

• A. Kc(1+ηD s)
• B. Kc(1 +1/ηD s)
• C. Kc ηD s
• D. Kc/ηD s

Explanation: A proportional-derivative controller has transfer function Gc(s)=Kc(1+τD s), where τD is the derivative time.

• A. Q0(T0 - T) = Ac . h (dT/dt)
• B. Q0T0 - QT = Ac . h (dT/dt)
• C. Q(T0 - T) = Ac . h (dT/dt)
• D. Q(T0 - T) = Ac . (dTH/dt)

Explanation: For a perfectly mixed tank, the material balance removes the level-change term from the energy balance, leaving Ac h(dT/dt)=Q0(T0−T) after…

• A. 1
• B. 2
• C. 3
• D. 4

Explanation: The number of root-locus branches equals the number of open-loop poles.

• A. Mercury in glass thermometer
• B. Nitrogen in steel thermometer
• C. Fused metal (Na or K) in steel thermometer
• D. Alcohol in glass thermometer

Explanation: Alcohol remains liquid at much lower temperatures than mercury, so an alcohol-in-glass thermometer has the lowest temperature range among…

• A. Volumetric expansion
• B. Pressure rise with temperature
• C. Linear expansion
• D. None of these

Explanation: Mercury expands nearly uniformly in volume when heated, and the capillary converts this volumetric expansion into a readable length or…

• A. Routh stability
• B. Nyquist
• C. Bode stability
• D. None of these

Explanation: The Bode stability criterion checks the gain at the phase-crossover frequency: a gain greater than unity indicates instability for the…

• A. Radiation pyrometer
• B. Thermocouple
• C. Photo-electric pyrometer
• D. Platinum resistance thermometer

Explanation: A platinum resistance thermometer is generally limited to roughly 850 to 1000°C in routine use, whereas thermocouples and optical or…

• A. Radiation pyrometer
• B. Mercury in glass thermometer
• C. Vapor pressure thermometer
• D. Platinum resistance thermometer

Explanation: A radiation pyrometer is primarily used for high-temperature, non-contact measurement and is not the usual instrument for sub-zero…

• A. 20
• B. 30
• C. 40
• D. 50

Explanation: Liquid manometers are intended for relatively low differential pressures, and their practical maximum is commonly taken as about 30 psi.

• A. Thermal conductivity through the paper
• B. Magnetic susceptibility
• C. Electrical resistance through the paper
• D. None of these

Explanation: Water conducts electricity better than dry paper, so the electrical resistance of paper decreases as its moisture content increases.

• A. Positive
• B. Atmospheric
• C. Very high
• D. Sub-atmospheric

Explanation: A McLeod gauge traps a known volume of gas and compresses it with mercury, allowing measurement of vacuum pressures below atmospheric…

• A. 0°
• B. 45°
• C. 90°
• D. 180°

Explanation: At a phase lag of 180°, negative feedback effectively becomes positive feedback; if the open-loop gain is then greater than unity…

• A. 250
• B. 350
• C. 550
• D. 700

Explanation: Pressurising the space above mercury with nitrogen suppresses mercury vapour formation and prevents separation of the mercury column…

• A. With the mercurial thermometer upto 350°C
• B. Directly
• C. All A., B. & C.
• D. Which is of higher magnitude

Explanation: Pyrometry is the measurement of high temperatures, generally by detecting thermal radiation without placing a sensor in direct contact…

• A. Optical pyrometer
• B. Radiation pyrometer
• C. Photoelectric pyrometer
• D. Thermocouples

Explanation: Optical, radiation, and photoelectric pyrometers are designed for non-contact measurement of red-hot objects in this high-temperature…

• A. Tank 3
• B. Tank 2
• C. Tank 1
• D. Tank 4

Explanation: The secondary sensor should detect the disturbance before it significantly affects the primary outlet temperature, while still being…

• A. 1
• B. 1/√2
• C. 0.5
• D. 0.25

Explanation: For a first-order system, the amplitude ratio is 1/√[1+(ωη)²]. With ωη = 1, it becomes 1/√2.

• A. 760.5
• B. 860.5
• C. 960.5
• D. 1060.5

Explanation: The silver point is the melting point of pure silver, traditionally taken as about 960.5°C in older calibration tables.

• A. s/(s2 - 1)
• B. s/(1 + s2)
• C. 1/(s2 - 1)
• D. 1/(s2 + 1)

Explanation: Using the standard transform pair, the Laplace transform of sin(at) is a/(s²+a²). Setting a = 1 gives 1/(s²+1).

• A. Dielectrics
• B. Semi conductors
• C. Insulators
• D. Conductors

Explanation: Thermistors are made from semiconductor materials whose resistance changes greatly with temperature.