Free Chemical Process Principles MCQs with Answers

• A. Kerosene
• B. Naphtha
• C. Diesel
• D. Lube oil

Explanation: Naphtha is the lightest and least viscous of these petroleum fractions because its molecules are smaller and have lower boiling ranges.

• A. Decreases gum formation
• B. Increases lead susceptibility
• C. Leads to corrosion
• D. Helps during stabilisation

Explanation: Sulphur compounds in gasoline can form corrosive products during combustion and storage, and they also contribute to sulphur oxide…

• A. Lower Reid vapour pressure
• B. Higher acid number
• C. Lower flash point and fire point
• D. Higher flash point and fire point

Explanation: Higher viscosity generally indicates a heavier, less volatile lubricating oil, which requires more heating to produce ignitable vapour.

• A. 0.42 × (% distilled at 204°C)
• B. 5 mm
• C. 0.84 × (% distilled at 204°C)
• D. 10 mm approximately

Explanation: The smoke volatility index combines smoke point with a volatility measure: SVI = smoke point + 0.42 times the percentage distilled at…

• A. Silica gel
• B. Silica-alumina
• C. Vanadium pentoxide
• D. Nickel

Explanation: Catalytic cracking commonly uses a silica-alumina catalyst, often in a zeolite-based form in modern units.

• A. None of these
• B. decompose
• C. Lighter/low boiling products are prone to thermal decomposition
• D. High purity products can be obtained thereby
• E. High boiling point products like heavy fuel oil & lubricating oils are heat sensitive and may

Explanation: Vacuum distillation lowers the boiling temperatures of heavy fractions, allowing them to be separated without severe heating.

• A. All A., B. and C.
• B. Added in LPG cylinders to detect gas leakage by its smell
• C. Undesirable in petrol, as they reduce its octane number
• D. Low boiling sulphur compounds

Explanation: Mercaptans are low-boiling sulfur compounds with an extremely strong odour, so they are added to LPG for leak detection.

• A. Paraffin
• B. Aromatic
• C. Olefin
• D. Naphthene

Explanation: The aniline point varies inversely with aromatic content: oil rich in aromatics dissolves aniline more readily and therefore has a lower…

• A. Petrol
• B. Water
• C. Diesel
• D. Crude petroleum

Explanation: For water, a pure substance, the freezing point and pour point are effectively the same because it solidifies at a definite temperature.

• A. 600-750
• B. 250-350
• C. 1000-1500
• D. 2000-2500

Explanation: The gross-to-net heating-value difference mainly represents the latent heat of vaporising water formed from hydrogen combustion.

• A. None of these
• B. Naphthenic
• C. Intermediate
• D. Paraffinic

Explanation: The Watson characterisation factor is generally above 12 for paraffinic crude, about 10 to 12 for naphthenic crude, and lower for aromatic…

• A. Sodium plumbite
• B. Sodium hydroxide
• C. Cupric chloride
• D. Potassium isobutyrate

Explanation: Doctor sweetening uses sodium plumbite, usually with elemental sulfur, to convert reactive mercaptans into less objectionable disulfides.

• A. Propane
• B. Diethylene glycol
• C. Aqueous solution (10% water) of diethylene glycol
• D. Methyl ethyl ketone (MEK)

Explanation: The Udex process uses aqueous diethylene glycol as a selective solvent for extracting light aromatics from hydrocarbon streams.

• A. Lower calorific value
• B. Higher ignition temperature
• C. Higher specific gravity
• D. Lower octane number

Explanation: Straight-run petrol generally has a lower octane number than alcohol fuels, because alcohols have high resistance to knocking.

• A. Ball and ring
• B. Impact
• C. Flame
• D. Viscosity

Explanation: The softening point of bitumen is measured by the ring-and-ball test, in which a steel ball causes the heated bitumen disc to flow through…

• A. Coking
• B. None of these
• C. Pyrolysis
• D. Visbreaking

Explanation: Coking, visbreaking, and pyrolysis are all thermal cracking processes, although their severity and products differ.

• A. Bauxite
• B. Fuller's earth
• C. All A., B. & C.
• D. Activated clay

Explanation: Older catalytic sweetening treatments may use porous solid materials such as bauxite, Fuller’s earth, and activated clay for removing or…

• A. (°API) × (100)/Aniline Point, °C
• B. (°API) × (Aniline Point, °C)/100
• C. (°API) × (100)/Aniline Point, °F
• D. (°API) × (Aniline Point, °F)/100

Explanation: Diesel index combines fuel density and ignition-related aniline point as API gravity multiplied by aniline point in °F, divided by 100.

• A. Increasing its oxidation stability
• B. Removal of dissolved gases from it
• C. Improving its lead susceptibility
• D. Increasing its vapour pressure

Explanation: Gasoline stabilisation removes dissolved light hydrocarbons and gases that would otherwise cause excessive vapour pressure and volatility.

• A. CnH2n+2O2
• B. CnH2n+2O2 (n ≥ 6)
• C. CnH2n-2O2
• D. CnH2n+6O2 (n ≤ 6)

Explanation: Naphthenic acids are cycloalkane carboxylic acids, so their general formula is CnH2n−2O2.