All Free Chemical Engineering MCQs with Answers

• A. Aromatic
• B. Naphthene
• C. Di-olefin
• D. Olefin

Explanation: Butadiene contains two carbon-carbon double bonds, so it is classified as a diolefin.

• A. Blending component for kerosene
• B. Blending component for petrol
• C. None of these
• D. Feedstock for fluid catalytic cracking unit

Explanation: Heavy gas oil from vacuum distillation has a high boiling range and is unsuitable for direct blending into petrol or kerosene.

• A. Anti-icing
• B. Anti-knocking
• C. Anti-gum forming
• D. Dewaxing

Explanation: Glycol lowers the freezing point of water and absorbs or ties up moisture, preventing ice formation in the fuel system or carburettor.

• A. 0.1
• B. 1
• C. 2.5
• D. 3.5

Explanation: Low-sulphur heavy stock furnace oil is generally specified at about 1% sulphur.

• A. Impart colour to it, for easy identification
• B. Prevent icing of the carburettor
• C. Minimise the gum formation
• D. Prevent the lead build up in engines

Explanation: Antioxidants slow oxidation reactions in petrol, thereby reducing the formation of gums during storage.

• A. Smoking tendency of hydrocarbons increases in the order: paraffins → isoparaffins →
• B. naphthenes → aromatics
• C. Smoking tendency of naphthenes decreases with its increasing molecular weight & also on
• D. Smoking tendency of paraffins increases with decrease in its molecular weight
• E. addition of double bond
• F. Smoking tendency of aromatics decreases with increase in its molecular weight

Explanation: The wrong statement is that paraffin smoking tendency increases as molecular weight decreases; it generally increases with increasing…

• A. R-S-H
• B. R-COOH
• C. R-S-R
• D. R-S-R'

Explanation: Mercaptans are thiols, formed when a hydrogen atom is attached to sulfur in an organic group, so their general formula is R–SH.

• A. 50
• B. 100
• C. 0
• D. ∞

Explanation: Alpha-methylnaphthalene is assigned a cetane number of 0 and serves as the low-cetane reference fuel.

• A. Sulphur
• B. Nitrogen
• C. None of these
• D. Oxygen

Explanation: Naphthenic acids are cycloalkane-based carboxylic acids, so they contain oxygen in the carboxyl group.

• A. Gas heavier than air
• B. Liquid heavier than water
• C. Gas lighter than air
• D. Liquid lighter than water

Explanation: At atmospheric pressure and temperature, LPG vaporizes because its boiling points are below room temperature.

• A. 20-25
• B. 0-5
• C. 60-75
• D. 100-120

Explanation: A good-burning kerosene commonly has a smoke point around 20–25 mm. A higher smoke point indicates cleaner burning with less soot, while…

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

Explanation: Furnace oil contains much heavier, less volatile hydrocarbons than diesel, kerosene, or petrol, so it requires the highest temperature to…

• A. 50
• B. 70
• C. 90
• D. 140

Explanation: Medium-viscosity furnace oil is commonly preheated to about 90°C so its viscosity falls enough for proper atomisation through the burner.

• A. Cyclohexane
• B. Butadiene
• C. Butene
• D. Acetylene

Explanation: Naphthenes are saturated cyclic hydrocarbons, and cyclohexane is a six-membered saturated ring.

• A. Low pressure & temperature
• B. High pressure & temperature
• C. High pressure and low temperature
• D. High temperature and low pressure

Explanation: Hydrocracking combines catalytic cracking with hydrogenation, so it requires elevated temperature and especially high hydrogen pressure.

• A. Cracking
• B. Polymerisation
• C. Reforming
• D. Isomerisation

Explanation: Catalytic reforming converts straight-run naphtha into higher-octane gasoline by forming aromatics and branched hydrocarbons, with…

• A. Steam reforming
• B. None of these
• C. Desulphurisation
• D. Distillation

Explanation: Solvent naphtha is obtained by fractionating virgin naphtha into selected boiling-range cuts, which is a distillation operation.

• A. Both A. & B.
• B. Aromatics content
• C. Molecular weight
• D. Neither 'a' nor 'b'

Explanation: Refractive index varies with both the molecular characteristics of the fuel, including molecular weight, and its aromatic content.

• A. 3
• B. 11
• C. 22
• D. 28

Explanation: The Watson or UOP characterization factor of crude petroleum is typically about 10 to 13, with approximately 11 being a representative…

• A. Is less than
• B. Is more than
• C. May be either more or less than
• D. Is same as

Explanation: Reid vapour pressure is measured under a fixed condition at 37.8°C, whereas true vapour pressure refers to equilibrium at the specified…