All Free Chemical Engineering MCQs with Answers

• A. n-paraffins
• B. Olefins
• C. Aromatics
• D. None of these

Explanation: Aromatics have a strong tendency to form soot during kerosene combustion, lowering the smoke point.

• A. Heavy fuel oil
• B. Residuum
• C. Casing head gasoline
• D. Straight run gasoline

Explanation: Catalytic reforming commonly receives straight-run gasoline, especially the naphtha fraction, to convert low-octane hydrocarbons into…

• A. 1
• B. 5
• C. 15
• D. 25

Explanation: A crude containing more than about 5 kg of salts, expressed as NaCl per 1,000 barrels, is conventionally termed salty crude.

• A. Ignition delay
• B. Resistance to knock
• C. Ignition temperature
• D. Smoke point

Explanation: Octane number measures gasoline's resistance to knocking in a spark-ignition engine.

• A. 1.5
• B. 3
• C. 6
• D. 12

Explanation: The high-pressure primary tower in a three-stage crude-distillation arrangement is commonly operated at about 3 kg/cm².

• A. Waxes
• B. Mercaptans
• C. Asphalt
• D. Diolefins

Explanation: The Unisol process uses caustic soda, with methanol assisting extraction, to remove mercaptans from gasoline.

• A. Diesel
• B. Kerosene
• C. Petrol
• D. Furnace oil

Explanation: Petrol contains the most volatile components among these products, giving it the lowest flash point, often well below 0°C.

• A. Is highly aromatic
• B. Has a large ignition delay
• C. Has a low diesel index
• D. Is highly paraffinic

Explanation: Aniline point rises as the paraffinic character of diesel increases; aromatic hydrocarbons dissolve aniline more readily and therefore…

• A. Fuel oil
• B. Naphtha
• C. Light diesel oil
• D. Petrol

Explanation: Fuel oil contains heavier, higher-molecular-weight hydrocarbons than naphtha, petrol or light diesel oil, so its resistance to flow is…

• A. Is the measure of its flash point
• B. Is the measure of variation of viscosity with temperature
• C. Should be low
• D. None of these

Explanation: Viscosity index expresses how strongly an oil’s viscosity changes with temperature.

• A. Pour point
• B. Viscosity
• C. Pressure drop on pumping
• D. All A., B. and C.

Explanation: Visbreaking mildly cracks heavy fuel oil, lowering its viscosity and usually its pour point.

• A. Mixed
• B. Asphalt
• C. Paraffin
• D. Naphthenic

Explanation: Paraffinic crudes are associated with wax, while asphaltic crudes yield asphalt.

• A. Alkylation
• B. Isomerisation
• C. Polymerisation
• D. None of these

Explanation: Isomerisation rearranges the straight-chain structure of n-paraffins into branched i-paraffins without changing the molecular formula.

• A. Methanol in Unisol process
• B. Naphthenic acid in Mercapsol process
• C. Both A. and B.
• D. Neither A. nor B.

Explanation: The Unisol solutizer uses methanol, while the Mercapsol process uses a naphthenic-acid-based solutizer.

• A. Furfural
• B. Phenol
• C. Propane
• D. Hexane

Explanation: Propane deasphalting uses liquid propane to dissolve the lighter oil components while rejecting asphaltenes.

• A. 30
• B. 45
• C. 75
• D. 95

Explanation: A cetane number of about 45 or higher is commonly specified for high-speed diesel to ensure satisfactory ignition quality.

• A. Naphtha
• B. Lubricating oils
• C. Wax
• D. Cracking feedstock

Explanation: Furfural selectively dissolves aromatic compounds from lubricating-oil fractions, leaving a more desirable paraffinic raffinate with…

• A. Naphthenes
• B. i-paraffins
• C. Aromatics
• D. Olefins

Explanation: Aromatics generally have the highest octane numbers because their stable ring structures resist knocking in spark-ignition engines.

• A. Aluminium chloride
• B. Nickel
• C. Iron
• D. Platinum on alumina

Explanation: Catalytic reforming commonly uses platinum dispersed on alumina, often with a second metal such as rhenium.

• A. Stiffness
• B. Lubricating properties (e.g. oilness)
• C. Service temperature
• D. Variation in viscosity with temperature

Explanation: The penetration test measures grease consistency, which is its resistance to deformation and is commonly described as stiffness or…