Free Chemical Process Principles MCQs with Answers

• A. 1-2
• B. 5-10
• C. 150-300
• D. 2000-3000

Explanation: Raw municipal sewage typically has a BOD of roughly 150 to 300 mg/L, reflecting its biodegradable organic load.

• A. Simple filtration
• B. Chlorination only
• C. Chemical coagulation
• D. Oxidation followed by settling & filtration

Explanation: Dissolved iron and manganese are first oxidised into insoluble hydroxides or oxides, which are then removed by settling and filtration.

• A. 0.5
• B. 17
• C. 357
• D. 1097

Explanation: The listed public-water limit for aldrin is approximately 17 μg/L. Aldrin is a persistent toxic pesticide, so its permissible…

• A. Destroys/removes pathogen from the sewage
• B. All A., B. & C.
• C. Destroys/removes pathogen much more effectively if the sewage is chlorinated
• D. Is not very effective for non-biodegradable substances (e.g. ABS) containing effluents

Explanation: Aerobic oxidation ponds reduce pathogens and biodegradable organic matter, but they are ineffective against many non-biodegradable…

• A. Dental cavity
• B. Tooth decay
• C. Fluorosis
• D. Respiratory disease

Explanation: Excess fluoride intake damages teeth and bones, with dental fluorosis being the characteristic effect at elevated levels.

• A. Photochemical smog
• B. Polyacrylonitrile
• C. Benzopyrene
• D. Peroxyacetyl nitrate (PAN) or methyl nitrite

Explanation: Nitrogen oxides reacting with unsaturated hydrocarbons in sunlight form secondary oxidants including peroxyacetyl nitrate, or PAN, which…

• A. 5
• B. 100
• C. 250
• D. 500

Explanation: River water commonly contains dissolved oxygen of several milligrams per litre, often around 5 mg/L under ordinary conditions.

• A. 50
• B. 1000
• C. 2000
• D. 5000

Explanation: The commonly used maximum allowable workplace concentration for carbon dioxide is 5000 ppm, or 0.5% by volume, for an eight-hour exposure.

• A. Organic
• B. Fatty
• C. Dissolved
• D. Inorganic

Explanation: Grit chambers remove heavy, coarse inorganic particles such as sand, gravel and cinders by settling.

• A. Skin diseases (e.g. dermatitis)
• B. Respiratory ailments (e.g. bronchitis)
• C. Silicosis
• D. Blurred vision

Explanation: Leather tanning exposes workers to chemicals, dyes and wet processing agents that commonly irritate the skin and cause dermatitis.

• A. Chlorination
• B. Treating in biological oxygen pond
• C. Chemical coagulation
• D. None of these

Explanation: Phenolic wastewater below about 100 mg/L can be treated biologically because microorganisms can degrade the phenol at this relatively low…

• A. 10
• B. 45
• C. 90
• D. 115

Explanation: Normal conversation is commonly listed in the approximate range of 45 to 60 dB, so 45 dB is the only suitable option given.

• A. Hydrogen sulphide
• B. Mercury
• C. Asbestos
• D. Cadmium

Explanation: Cadmium exposure, even at relatively small amounts over time, is linked with hypertension and cardiovascular damage as well as kidney…

• A. All A., B. and C.
• B. Corrosion, tarnishing & soiling of metals
• C. Reduced strength of textiles
• D. Fading of dyes on textiles

Explanation: Sulphur dioxide dissolves in atmospheric moisture to form acidic species that attack metals, soil surfaces and textile fibres, while also…

• A. Turbidity
• B. Caustic embrittlement
• C. Suspended silica
• D. Dissolved oxygen

Explanation: Phosphate conditioning with trisodium phosphate helps prevent caustic embrittlement by controlling free caustic soda and converting…

• A. Oxides of sulphur
• B. Oxides of nitrogen
• C. Carbon monoxide
• D. Hydrogen sulphide

Explanation: Oxides of sulphur, especially sulphur dioxide, are conventionally treated as major air-pollutant constituents because they are emitted in…

• A. Green house gases
• B. Use of silencers
• C. Vibration damping
• D. Tree plantation

Explanation: Greenhouse gases contribute to global warming but do not control or reduce noise pollution.

• A. Hydrocarbons
• B. Hydrogen fluoride
• C. Hydrogen sulphides
• D. Nitrogen dioxide

Explanation: Hydrogen fluoride in air supplies fluoride that can be absorbed by the body and cause fluorosis, including bone damage.

• A. 20
• B. 100
• C. 400
• D. 200

Explanation: SO₂ becomes rapidly life-threatening at very high concentrations, with about 400 ppm commonly cited as a potentially fatal level.

• A. 90
• B. 120
• C. 150
• D. 180

Explanation: A nearby automobile horn commonly produces a sound level of roughly 110 to 120 dB, making 120 dB the closest choice at 1.5 metres.