All Free Chemical Engineering MCQs with Answers

• A. Hydrochloric acid
• B. Lime
• C. Copper sulphate
• D. Sodium sulphate

Explanation: Lime promotes coagulation and floc formation in sewage, causing suspended particles to aggregate and settle more rapidly.

• A. Evaporation & chemical precipitation
• B. Biological methods & adsorption in ion exchange materials
• C. All A., B. & C.
• D. Fixing into a solid mass with cement and sinking deep in the sea

Explanation: Radioactive wastes may be concentrated by evaporation, treated by precipitation or ion exchange, and immobilised in cement before…

• A. Nitric acid making
• B. Nitrogenous fertiliser
• C. Any of these
• D. Detergent

Explanation: Nitrogen oxides are central emissions in nitric-acid and nitrogenous-fertiliser manufacture because nitrogen compounds undergo oxidation…

• A. Chemical coagulation
• B. Circular clarifier
• C. Mechanical flocculation
• D. Sedimentation tank

Explanation: Very fine particles and colloids remain suspended because they have low settling velocities and surface charges that prevent aggregation.

• A. Ferrous sulphate
• B. Alum
• C. Lime
• D. Hydrazine

Explanation: Alum, usually aluminium sulphate, hydrolyses in water to form gelatinous aluminium hydroxide flocs that trap colloids and suspended…

• A. Poor visibility due to sky darkening
• B. Irritation in eyes
• C. All A., B. and C.
• D. Respiratory trouble

Explanation: Sulphurous smog combines smoke particles and fog, reducing visibility and irritating the eyes and respiratory system.

• A. 0.1 to 1
• B. 15 to 20
• C. 10 to 15
• D. 3 to 6

Explanation: Rapid sand filters operate at much higher rates than slow sand filters, typically about 3 to 6 kL/m²/h in standard treatment design data.

• A. Industrial chimney exhaust
• B. Automobiles exhaust
• C. Forest fire
• D. Photochemical oxidation of organic matter

Explanation: Automobile exhaust is a major continuous source of urban pollutants such as carbon monoxide, nitrogen oxides, hydrocarbons and particulate…

• A. Incineration
• B. Biological oxidation
• C. Composting
• D. None of these

Explanation: Composting is the controlled biological decomposition of biodegradable organic waste, usually under aerobic conditions.

• A. SO2 & SO3
• B. NO2
• C. NH3
• D. CO

Explanation: Fertiliser plants commonly release ammonia, nitrogen oxides and sulphur oxides depending on the process and fuel used.

• A. Both B. and C.
• B. Digestion
• C. Sedimentation
• D. Filtration

Explanation: An Imhoff tank has an upper chamber for sedimentation and a lower chamber where the settled sludge undergoes anaerobic digestion.

• A. Discharging in the river stream
• B. Quenching of hot coke
• C. Filtration and recycling for cooling coke oven gas
• D. None of these

Explanation: Phenolic wastewater from coke ovens has traditionally been reused for quenching hot coke, which consumes the water and limits direct…

• A. Paralysis of muscles & loss of appetite
• B. Nervous depression
• C. Gastritis and diarrhea
• D. All A., B. and C.

Explanation: Lead from tetraethyl-leaded petrol can damage the nervous system and muscles and produce appetite loss and gastrointestinal symptoms such…

• A. Mud balls
• B. Shrinkage of filtering media
• C. Air binding
• D. Expansion of filtering media

Explanation: Inadequately washed sand retains fine clay and sludge; during filtration and backwashing these bind sand grains into dense lumps called…

• A. 1 to 2
• B. 4 to 5
• C. 9 to 10
• D. 15 to 20

Explanation: Oxidation ponds require a relatively long detention period, commonly about 4 to 5 weeks, so microorganisms have enough time to reduce the…

• A. Reduction in strength of leather & cloth
• B. Acceleration of corrosion rates of metals
• C. All A., B. and C.
• D. Increased drying & hardening time of paints

Explanation: Sulfur dioxide in chimney gases attacks leather and textiles, accelerates metal corrosion, and interferes with the drying and hardening of…

• A. Cancer
• B. Corrosion
• C. Asphyxiation
• D. Bronchitis

Explanation: Nitrogen dioxide is a strong respiratory irritant that inflames the airways and can produce bronchitis, especially after prolonged…

• A. Alum (aluminium sulphate)
• B. Lime
• C. Ferric chloride
• D. Sodium aluminate

Explanation: Alum, or aluminium sulphate, is the most commonly used coagulant for turbid water because it neutralizes particle charges and forms flocs…

• A. Hearing loss
• B. All A., B. & C.
• C. Nervousness & fatigue
• D. Rupture of ear drum

Explanation: Excessive workplace noise can cause temporary or permanent hearing loss, extreme exposure can rupture the eardrum, and prolonged exposure…

• A. 3
• B. 30
• C. 7
• D. 70

Explanation: Furnace noise rises when the fuel firing rate and combustion turbulence increase; a 50% increase is commonly taken as producing roughly a…