All Free Chemical Engineering MCQs with Answers

• A. 0
• B. 1
• C. 2
• D. 3

Explanation: For a rate law r = kCⁿ, tripling concentration changes the rate by 3ⁿ. Since the rate becomes 9 times greater, 3ⁿ = 9 = 3², so the…

• A. Ratio of liquid depth to tank diameter (i.e. the filling ratio) recommended for most purposes is 1
• B. Filling ratio for dispersing gas in a liquid is 2 for sufficiently long contact period
• C. Flat bottom and conical bottom vessels have low agitation efficiency for agitation of heavy solids in liquids
• D. Dished bottom vessel has very high power consumption

Explanation: A dished bottom generally improves liquid circulation and solid suspension, rather than requiring very high power consumption.

• A. Pot type reactor
• B. A vapor phase reactor
• C. A liquid phase reactor
• D. A liquid phase catalytic reactor

Explanation: A vapor-phase reactor generally has a smaller liquid inventory and avoids hazards associated with boiling, liquid leakage and catalyst…

• A. 1
• B. < 1
• C. > 1
• D. Equal to the order of reaction

Explanation: For a positive-order reaction, the rate decreases as conversion increases, so a mixed reactor operates everywhere at the low exit…

• A. Laminar flow
• B. Eddy diffusivity = 0
• C. Plug flow
• D. Complete back mixing

Explanation: The Peclet number compares convective transport with axial dispersion. Pe = 0 means dispersion dominates completely, corresponding to…

• A. Aluminium chloride
• B. Alumina
• C. Nickel
• D. Phosphoric acid

Explanation: Aluminium chloride, usually with hydrogen chloride, is the classical catalyst system for paraffin isomerisation.

• A. 100
• B. 200-300
• C. 1000-10000
• D. 10

Explanation: Catalysts strongly accelerate the cracking of olefins by providing a lower-energy reaction pathway, making their cracking rate roughly…

• A. Enhances the desulphurisation process
• B. Both A. and B.
• C. Minimises coke formation
• D. Neither A. nor B.

Explanation: Hydrogen reacts with sulphur compounds over the hydrofining catalyst, increasing their conversion to removable hydrogen sulphide.

• A. Causes olefins to combine with each other
• B. Converts iso-paraffin into olefin
• C. Causes olefins to combine with iso-paraffins
• D. Converts olefin into paraffin

Explanation: In petroleum alkylation, an olefin combines with an iso-paraffin such as isobutane to form a higher-molecular-weight, highly branched…

• A. None of these
• B. Increases the rate of reaction
• C. Produces high octane number gasoline
• D. Increases coke formation

Explanation: In catalytic reforming, higher pressure favours hydrogenation and suppresses coke deposition, while lower pressure generally promotes…

• A. Catalytic naphtha - coking naphtha - virgin naphtha
• B. Coking naphtha - virgin naphtha - catalytic naphtha
• C. Virgin naphtha - catalytic naphtha - coking naphtha
• D. Virgin naphtha - coking naphtha - catalytic naphtha

Explanation: The usual preference listed for catalytic-reformer feed is coking naphtha, followed by virgin naphtha and then catalytic naphtha.

• A. Stabilisation
• B. Visbreaking
• C. Cracking
• D. Reforming

Explanation: Petroleum coke is produced by coking, particularly delayed coking, in which heavy residues undergo severe thermal cracking and leave a…

• A. 80
• B. 87
• C. 92
• D. 97

Explanation: Two-stage fluidised catalytic cracking gives a highly upgraded gasoline, with an octane number commonly quoted near 97.

• A. Cracked gases rich in C2 & C4 olefins
• B. Naphtha
• C. Low boiling aromatics
• D. None of these

Explanation: Polymerisation units use olefin-rich cracked gases, especially light olefins such as ethylene and butylene, as feedstock.

• A. Gives higher yield of petrol
• B. Lower octane number of petrol
• C. Higher sulphur content in the product
• D. Higher gum forming material in petrol

Explanation: Catalytic cracking converts heavy petroleum fractions into more gasoline-range products and generally gives a higher gasoline yield than…

• A. Dubbs process
• B. T.C.C. moving bed process
• C. Fluidised bed catalytic cracking process
• D. Houdry's fixed bed process

Explanation: Fluidised-bed catalytic cracking, or FCC, is the dominant modern refinery cracking process because its continuously circulating catalyst…

• A. Coke
• B. Lube oil
• C. Petrolatum
• D. Gasoline

Explanation: Cracking breaks large hydrocarbon molecules into smaller, more valuable molecules, with gasoline being the principal desired product.

• A. Uses natural gas as feed
• B. Produces fuel oil of lower viscosity
• C. Is carried out at atmospheric pressure
• D. Produces gasoline only

Explanation: Visbreaking is a mild thermal cracking treatment of heavy petroleum fractions that reduces the viscosity of the resulting residual fuel…

• A. H2SO4
• B. H3PO4
• C. Both A. and B.
• D. AlCl3

Explanation: Catalytic polymerisation of light olefins to polymer gasoline has been carried out using either sulphuric acid or phosphoric acid…

• A. Ethane
• B. Ethyl alcohol
• C. Methane
• D. Methyl alcohol

Explanation: MTBE is formed by acid-catalysed addition of methanol to isobutylene: isobutylene plus methyl alcohol gives methyl tertiary butyl ether.