All Free Chemical Engineering MCQs with Answers

• A. 273°C
• B. 273°K
• C. 100°C
• D. 200°C

Explanation: At constant pressure, Charles's law gives V/T = constant using absolute temperature.

• A. Joule
• B. Watt
• C. Both B. & C.
• D. Joule/Second

Explanation: Power is the rate of doing work, so its SI unit is joule per second, which is named the watt.

• A. Stoke
• B. Poise
• C. Both B. & C.
• D. gm/cm sec

Explanation: Dynamic viscosity has the CGS unit poise, defined as gram per centimetre-second, or g/(cm·s).

• A. Neither A. nor B.
• B. Oxidation number
• C. Both A. & B.
• D. Number of electrons

Explanation: Reduction means gain of electrons, while oxidation number decreases during reduction.

• A. NH3
• B. CO2
• C. H2S
• D. CH4

Explanation: Ammonia is highly soluble in water because it reacts with water to form ammonium and hydroxide ions.

• A. T2
• B. T
• C. √T
• D. 1/√T

Explanation: From kinetic theory, the characteristic molecular speed varies as the square root of absolute temperature, v ∝ √T.

• A. Weight % of the solute
• B. Mole fraction of the solute
• C. Molality
• D. Molarity

Explanation: On heating, the solution volume generally expands while the amount of solute remains constant, so molarity decreases.

• A. C4H9OH
• B. C3H21OH
• C. (C2H4)2H2.OH
• D. C2H33OH

Explanation: The carbon, hydrogen and oxygen amounts correspond to 48/12 = 4, 10/1 = 10 and 16/16 = 1 mole, giving C4H10O.

• A. °Be = 200(G-1)
• B. °Be = (140/G) - 130
• C. °Be = 145 - (145/G)
• D. °Be = (400/G) - 400

Explanation: For liquids lighter than water, the specific gravity G is less than one, so the Baumé relation is °Be = 140/G − 130.

• A. 2.5
• B. 42.5
• C. 56
• D. 2800

Explanation: At N.T.P., one gram-mole of an ideal gas occupies 22.4 L, so 56 L represents 2.5 moles.

• A. Litre
• B. gm
• C. gm.mole
• D. kg

Explanation: Molality is based on the mass of solvent, not the solution volume: it is gram-moles of solute per kilogram of solvent.

• A. Buffer
• B. Non-ideal
• C. Ideal
• D. Colloidal

Explanation: A buffer contains a weak acid and its conjugate base, or a weak base and its conjugate acid, so it resists pH changes when small amounts…

• A. Trouton's rule
• B. Kopp's rule
• C. Antoine equation
• D. Kistyakowsky equation

Explanation: Kopp's rule estimates the molar heat capacity of a solid compound by adding the atomic heat capacities of its constituent elements.

• A. N2O4
• B. N2O3
• C. N2O5
• D. None of these

Explanation: The masses correspond to 28/14 = 2 gram-atoms of nitrogen and 80/16 = 5 gram-atoms of oxygen.

• A. Increases
• B. Decreases
• C. Remains unchanged
• D. Either A. or B.; depends on the substance

Explanation: Over ordinary temperature ranges, the heat capacity of most substances increases because more molecular energy modes become accessible as…

• A. - 136.5°K
• B. -136.5°C
• C. -273°C
• D. 0°K

Explanation: At constant pressure, Charles's law gives V/T = constant using absolute temperature.

• A. 3
• B. 100
• C. 1000
• D. None of these

Explanation: A pH decrease of one unit means a tenfold increase in hydrogen-ion concentration.

• A. Formation
• B. Vaporisation
• C. Reaction
• D. Combustion

Explanation: Calorific value is the heat released when a unit amount of fuel undergoes complete combustion.

• A. °F = (°C + 17.778) × 1.8
• B. Temperature difference of 1°K = 1°C = 9/5°F
• C. °C = (F- 32) × 0.555
• D. °R = 273 + °F

Explanation: The Rankine conversion is °R = °F + 459.67, not °F + 273. The other expressions correctly represent temperature differences or the…

• A. 0.065
• B. 0.65
• C. 6.5
• D. 65

Explanation: At NTP, 224 cc of hydrogen represents 224/22400 = 0.01 mol H₂. The zinc-to-hydrogen molar ratio is 1:1, so the required zinc mass is 0.01…