All Free Chemical Engineering MCQs with Answers

• A. No change
• B. Decrease
• C. Exponential decrease
• D. Increase

Explanation: Resistance follows R = ρL/A, so stretching increases the wire length while reducing its cross-sectional area.

• A. Polarimeter
• B. Polarograph
• C. Dilatometer
• D. Refractometer

Explanation: A polarimeter measures the rotation of plane-polarised light caused by an optically active solution.

• A. Platinum-rhodium
• B. Tungsten-molybdenum
• C. Chromel-alumel
• D. Iron-constantan

Explanation: Tungsten-molybdenum thermocouples withstand higher temperatures than platinum-rhodium, chromel-alumel, and iron-constantan types.

• A. Of cold junction only
• B. Of hot junction only
• C. Difference between hot and cold junctions
• D. Difference between cold junction and atmospheric temperature

Explanation: Thermocouple emf is produced by the temperature difference between its hot and cold junctions, with the exact relation being nonlinear.

• A. Mercury in glass thermometer
• B. Mercury 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 is used for low-temperature…

• A. Mercury
• B. Water
• C. Methyl alcohol
• D. Carbon-tetrachloride

Explanation: Among the listed liquids, mercury has the smallest volumetric expansion coefficient under ordinary thermometer conditions.

• A. Pitot tube
• B. Magnetic flowmeter
• C. Flow nozzle type flowmeter
• D. Turbine flowmeter

Explanation: A magnetic flowmeter measures conductive-fluid velocity through the voltage induced in the fluid by a magnetic field, so density…

• A. One cell
• B. No cell
• C. Three cells
• D. Two cells

Explanation: A pH meter uses two electrode systems: a glass measuring electrode and a reference electrode, often assembled as a combined electrode.

• A. Peltier
• B. Thomson
• C. Seebeck
• D. None of these

Explanation: The Peltier effect is the absorption or release of heat at the junction of two dissimilar conductors when current passes through it.

• A. Stress
• B. Contraction/expansion due to changes in temperature
• C. Deflection
• D. Strain

Explanation: A dilatometer measures dimensional change, especially expansion or contraction, as temperature changes.

• A. Seebeck effect
• B. Wien's law
• C. Kirchoff's law
• D. Peltier effect

Explanation: A disappearing-filament optical pyrometer compares the brightness of a heated filament with the radiation from the hot body, using the…

• A. Is a constant
• B. Grows exponentially with time
• C. Grows linearly with time
• D. Decays linearly with time

Explanation: A double pole at the origin gives an inverse-Laplace term proportional to t, since L⁻¹{1/s²} = t.

• A. Temperature
• B. Pressure
• C. Flow rate
• D. Concentration

Explanation: Gas chromatography separates components and measures their detector responses, which are converted into the concentration or composition…

• A. All A , B & C.
• B. Reducing the volume of the capillary to a minimum
• C. Reducing the volume of the receiving element to a minimum
• D. Making the volume of thermometer bulb as large as conveniently possible

Explanation: Ambient-temperature effects are reduced by making the bulb volume large and the capillary and receiving-element volumes small, so most of…

• A. Emission spectroscopy
• B. Flame photometry
• C. Polarimetry
• D. Oscillometry

Explanation: Sugar solutions rotate the plane of polarised light, and the angle of rotation is related to concentration, which is the basis of…

• A. None of these
• B. Hydrogen
• C. Nitrogen
• D. Helium

Explanation: Helium remains suitable for gas-thermometer measurements at temperatures below 0°C and is especially useful at very low temperatures…

• A. Bourdon gauge
• B. U-tube manometer
• C. Inclined tube manometer
• D. Pirani gauge

Explanation: A Bourdon gauge is a robust mechanical instrument for measuring the relatively high pressures encountered in an ammonia reactor.

• A. Chromatograph
• B. Polarograph
• C. Refractometer
• D. None of these

Explanation: A polarograph can determine the concentrations of electroactive metal ions, making it useful for analysing the metallic constituents of…

• A. 1 + et
• B. 1 - et
• C. 1 - e-t
• D. 1 + e-t

Explanation: Interpreting the expression as 1/[s(1+s)], partial fractions give 1/s − 1/(s+1), whose inverse transform is 1 − e⁻ᵗ.

• A. Becomes more oscillatory (frequency increases)
• B. Becomes less oscillatory (frequency decreases)
• C. Gets amplified (magnitude increases)
• D. Gets attenuated (magnitude decreases)

Explanation: A linear first-order system preserves the input frequency but its transfer-function magnitude is less than one in the attenuating…