Structure and uses of trichloroethylene MCQs With Answer

Structure and uses of trichloroethylene MCQs With Answer are essential for B. Pharm students mastering industrial solvents, toxicology, and analytical methods. Trichloroethylene (TCE) is a chlorinated alkene (C2HCl3) widely used as a degreasing solvent and chemical intermediate; understanding its molecular structure, metabolism (formation of trichloroacetic and dichloroacetic acids, glutathione conjugates), environmental fate, analytical detection, and health risks is crucial for pharmacy practice and safety. This collection provides focused, exam-oriented MCQs that reinforce core concepts like physicochemical properties, mechanism of toxicity, regulatory concerns, and remediation strategies. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the correct molecular formula of trichloroethylene?

• C2HCl3
• C2Cl4
• C2H2Cl2
• C2H3Cl

Correct Answer: C2HCl3

Q2. Which structural feature defines trichloroethylene?

• A carbon–carbon double bond with three chlorine substituents
• A saturated ethane backbone with three chlorines
• An aromatic ring bearing chlorine
• A carbonyl functional group

Correct Answer: A carbon–carbon double bond with three chlorine substituents

Q3. Which of the following best describes the predominant functional group in TCE?

• Alkene
• Alcohol
• Ether
• Aldehyde

Correct Answer: Alkene

Q4. Trichloroethylene is routinely used in industry primarily as a:

• Degreasing and metal-cleaning solvent
• Systemic antibiotic
• Food preservative
• Fuel additive

Correct Answer: Degreasing and metal-cleaning solvent

Q5. Which metabolic pathway is most associated with TCE-induced nephrotoxicity?

• Glutathione conjugation yielding nephrotoxic metabolites
• Simple hydrolysis to ethanol
• Direct renal excretion as unchanged TCE
• Conversion to carbon dioxide and water only

Correct Answer: Glutathione conjugation yielding nephrotoxic metabolites

Q6. Major oxidative metabolites of trichloroethylene formed via cytochrome P450 include:

• Trichloroacetic acid and dichloroacetic acid
• Benzoic acid and salicylic acid
• Acetaldehyde and acetic acid
• Phenol and catechol

Correct Answer: Trichloroacetic acid and dichloroacetic acid

Q7. Which analytical technique is most commonly used for sensitive quantification of TCE in biological and environmental samples?

• Gas chromatography coupled with mass spectrometry (GC-MS)
• UV–visible spectrophotometry
• High-performance liquid chromatography with refractive index detection
• Polarimetry

Correct Answer: Gas chromatography coupled with mass spectrometry (GC-MS)

Q8. Trichloroethylene’s lipophilicity implies it:

• Accumulates in fatty tissues and crosses membranes readily
• Is strongly water-soluble and does not cross membranes
• Acts as a strong electrolyte in plasma
• Is chemically identical to water

Correct Answer: Accumulates in fatty tissues and crosses membranes readily

Q9. Which property of TCE contributes to its widespread groundwater contamination risk?

• High volatility and persistence under some subsurface conditions
• Complete and immediate biodegradability in all soils
• Strong binding to clay that prevents movement
• Instant photodegradation in subsurface environments

Correct Answer: High volatility and persistence under some subsurface conditions

Q10. The presence of TCE in groundwater under anaerobic conditions can lead to formation of which hazardous product through reductive dechlorination?

• Vinyl chloride
• Methane
• Carbon tetrachloride
• Formaldehyde

Correct Answer: Vinyl chloride

Q11. Which clinical effect is characteristic of acute high-level TCE exposure?

• CNS depression leading to dizziness and loss of consciousness
• Immediate renal failure without CNS effects
• Severe hyperactivity and seizures only
• Hypoglycemia without neurologic symptoms

Correct Answer: CNS depression leading to dizziness and loss of consciousness

Q12. Which organ system is most associated with chronic TCE toxicity and carcinogenicity in humans?

• Kidneys
• Pancreas
• Skin
• Thyroid

Correct Answer: Kidneys

Q13. The IARC classification for trichloroethylene (as of recent reviews) categorizes it as:

• Carcinogenic to humans (Group 1)
• Not classifiable as to carcinogenicity (Group 3)
• Probably not carcinogenic
• Only carcinogenic in animals, not humans

Correct Answer: Carcinogenic to humans (Group 1)

Q14. In occupational health, biological monitoring of TCE exposure often measures which urinary metabolite?

• Trichloroacetic acid (TCA)
• Urinary glucose
• Creatinine kinase
• Unchanged TCE only

Correct Answer: Trichloroacetic acid (TCA)

Q15. Which statement about TCE’s flammability is most accurate?

• TCE is generally nonflammable under normal handling conditions
• TCE is highly explosive at room temperature
• TCE ignites spontaneously in air at 20°C
• TCE is a nonvolatile solid

Correct Answer: TCE is generally nonflammable under normal handling conditions

Q16. Which remediation approach is used for TCE-contaminated groundwater by stimulating anaerobic biodegradation?

• Enhanced reductive dechlorination via electron donors
• Oxidative photolysis in deep aquifers
• Thermal incineration in situ
• Simple dilution without treatment

Correct Answer: Enhanced reductive dechlorination via electron donors

Q17. Which intermediate metabolite is associated with TCE hepatotoxicity and CNS effects and is also related to chloral hydrate formation?

• Chloral (hydrate)
• Benzoic acid
• Acetone
• Formic acid

Correct Answer: Chloral (hydrate)

Q18. For analytical sampling of volatile organics like TCE in air, which sampling method is commonly used?

• Activated charcoal or sorbent tubes followed by thermal desorption
• Direct turbidity measurement
• Blood culture techniques
• Tissue biopsy only

Correct Answer: Activated charcoal or sorbent tubes followed by thermal desorption

Q19. Why are chlorinated solvents like TCE less reactive toward simple electrophilic addition at the double bond compared with simple alkenes?

• Electron-withdrawing chlorine atoms reduce electron density at the double bond
• Chlorine atoms donate electrons and increase reactivity
• The double bond in TCE is aromatic
• Because TCE is ionic and not covalent

Correct Answer: Electron-withdrawing chlorine atoms reduce electron density at the double bond

Q20. Historically, trichloroethylene was used in medicine as:

• An inhalational anesthetic and analgesic in the past
• A modern antiviral drug
• A topical antiseptic still used today
• A steroidal anti-inflammatory agent

Correct Answer: An inhalational anesthetic and analgesic in the past

Q21. Which physicochemical property explains why TCE partitions into biological membranes?

• High octanol–water partition coefficient (lipophilicity)
• High aqueous solubility
• Strong ionic charge
• Large molecular size preventing diffusion

Correct Answer: High octanol–water partition coefficient (lipophilicity)

Q22. Which enzyme family primarily catalyzes oxidative metabolism of TCE in the liver?

• Cytochrome P450 monooxygenases
• Alcohol dehydrogenases
• Proteases
• DNA polymerases

Correct Answer: Cytochrome P450 monooxygenases

Q23. Which urinary finding suggests exposure to TCE rather than another solvent?

• Elevated levels of trichloroacetic acid
• High urinary benzene
• Increased urinary lead
• Glucosuria only

Correct Answer: Elevated levels of trichloroacetic acid

Q24. A key concern with chronic environmental exposure to TCE is its potential to cause:

• Certain cancers, particularly kidney cancer
• Immediate bacterial infections
• Fractures of long bones
• Primary tooth decay

Correct Answer: Certain cancers, particularly kidney cancer

Q25. Which of the following best describes TCE’s water solubility?

• Low to moderate solubility in water
• Completely insoluble in water
• Extremely high solubility like ethanol
• Infinite solubility forming ionic solutions

Correct Answer: Low to moderate solubility in water

Q26. The primary occupational route of TCE exposure for workers is:

• Inhalation of vapor
• Oral ingestion of large tablets
• Ultraviolet radiation
• Direct thermal conduction

Correct Answer: Inhalation of vapor

Q27. Which chemical change during TCE metabolism is associated with formation of trichloroacetic acid?

• Oxidation of the vinyl group via P450 enzymes
• Direct conjugation with sulfate only
• Reduction to methane
• Saponification to fatty acids

Correct Answer: Oxidation of the vinyl group via P450 enzymes

Q28. Which environmental fate process commonly removes TCE from surface water bodies?

• Volatilization to the atmosphere
• Complete mineralization by sunlight within seconds
• Transformation to harmless water by simple dilution
• Absorption to rocks permanently

Correct Answer: Volatilization to the atmosphere

Q29. Which personal protective equipment (PPE) is most important when handling TCE in a lab setting?

• Proper respiratory protection and chemical-resistant gloves
• Cotton gloves and a paper mask
• Only safety goggles without gloves
• Sunglasses and sandals

Correct Answer: Proper respiratory protection and chemical-resistant gloves

Q30. Which metabolite of TCE is often used as a biomarker in epidemiological studies for exposure assessment?

• Trichloroacetic acid (TCA)
• Acetaminophen
• Ethylbenzene
• Sodium chloride

Correct Answer: Trichloroacetic acid (TCA)

Q31. Compared with benzene, trichloroethylene is chemically classified as a:

• Chlorinated alkenic hydrocarbon
• Aromatic hydrocarbon
• Primary alcohol
• Carboxylic acid

Correct Answer: Chlorinated alkenic hydrocarbon

Q32. Which cellular mechanism contributes to TCE-induced carcinogenesis according to mechanistic studies?

• Reactive metabolites causing DNA damage and oxidative stress
• Direct mechanical disruption of DNA only
• Immediate cell dehydration without DNA effects
• Blocking of all transcription permanently

Correct Answer: Reactive metabolites causing DNA damage and oxidative stress

Q33. In pharmaceutical manufacturing, careful control of residual TCE is important because:

• It is toxic and a potential carcinogen, requiring low residual solvent levels
• It enhances drug efficacy if present
• It stabilizes proteins at high concentrations intentionally
• It acts as a preservative in tablets

Correct Answer: It is toxic and a potential carcinogen, requiring low residual solvent levels

Q34. Which monitoring technique is preferred for volatile organics in blood samples to avoid loss of analyte?

• Headspace GC-MS
• Direct UV inspection
• Paper chromatography only
• Microscopy

Correct Answer: Headspace GC-MS

Q35. Which statement about TCE and cardiac effects is correct?

• TCE exposure can sensitize the myocardium to catecholamine-induced arrhythmias
• TCE strengthens cardiac conduction permanently
• TCE acts as a selective beta-blocker
• TCE increases myocardial glucose storage exclusively

Correct Answer: TCE exposure can sensitize the myocardium to catecholamine-induced arrhythmias

Q36. Which chemical reaction pathway is a major route for natural attenuation of TCE in aerobic soils?

• Limited aerobic biodegradation and volatilization; attenuation is slow
• Immediate abiotic conversion to methane
• Complete oxidation to oxygen and water within hours
• Rapid polymerization forming solid plastics

Correct Answer: Limited aerobic biodegradation and volatilization; attenuation is slow

Q37. Which occupational control is most effective at reducing inhalation exposure to TCE?

• Local exhaust ventilation at the source
• Removing all gloves and masks
• Opening windows only without ventilation systems
• Using acoustic barriers

Correct Answer: Local exhaust ventilation at the source

Q38. Which reagent is commonly used to detect chlorinated solvents like TCE in simple qualitative field tests?

• Colorimetric detector tubes specific for halogenated hydrocarbons
• Litmus paper for pH measurement
• Silver nitrate for halides in solution only
• Biuret reagent for proteins

Correct Answer: Colorimetric detector tubes specific for halogenated hydrocarbons

Q39. In terms of chemical stability, TCE is best described as:

• Relatively stable but susceptible to degradation under specific environmental conditions
• Extremely reactive and unstable at room temperature
• Non-degradable and permanently inert in all media
• Instantly polymerizing in air

Correct Answer: Relatively stable but susceptible to degradation under specific environmental conditions

Q40. Which property makes TCE useful as an extraction solvent in pharmaceutical synthesis?

• Ability to dissolve lipophilic organic compounds effectively
• High polarity for dissolving salts
• Strong acidity for catalyzing reactions
• Biodegradability that prevents residues

Correct Answer: Ability to dissolve lipophilic organic compounds effectively

Q41. The presence of which gene-environment interaction factor can influence individual susceptibility to TCE toxicity?

• Polymorphisms in glutathione S-transferase enzymes
• Eye color variations only
• Blood type O exclusively
• Height differences only

Correct Answer: Polymorphisms in glutathione S-transferase enzymes

Q42. Which metabolite pathway is more associated with systemic oxidative metabolites in TCE exposure?

• Cytochrome P450 oxidation generating trichloroacetic acid and dichloroacetic acid
• Direct conjugation to glucose
• Formation of long-chain fatty acids only
• Sulfation to produce sulfate esters exclusively

Correct Answer: Cytochrome P450 oxidation generating trichloroacetic acid and dichloroacetic acid

Q43. In environmental forensic studies, compound-specific isotope analysis (CSIA) can help distinguish:

• Biodegradation versus physical dilution of TCE
• Color differences in polluted water only
• Exact source company name from a single sample
• Whether TCE is chemically identical to benzene

Correct Answer: Biodegradation versus physical dilution of TCE

Q44. Which precaution is important when heating waste streams containing TCE during disposal?

• Avoid high-temperature incineration without controls because decomposition can form hazardous byproducts
• Heat freely to 3000°C without monitoring
• Add simple water and pour down the sink
• Allow open burning in the laboratory hood

Correct Answer: Avoid high-temperature incineration without controls because decomposition can form hazardous byproducts

Q45. Which statement about TCE in perfume or consumer products is correct historically?

• TCE was formerly used in consumer products but has declined due to toxicity concerns
• TCE is widely used today as an ingredient in baby food
• TCE is the primary component of modern hand sanitizers
• TCE is a food-grade solvent commonly used in beverages

Correct Answer: TCE was formerly used in consumer products but has declined due to toxicity concerns

Q46. Which analytical sample matrix is commonly analyzed when assessing recent occupational inhalation exposure to TCE?

• Blood or exhaled breath samples
• Hair length only
• Nail clippings exclusively
• Saliva without analytical methods

Correct Answer: Blood or exhaled breath samples

Q47. Which statement describes the environmental persistence of TCE in anaerobic aquifers?

• TCE can persist but may be biodegraded reductively to toxic intermediates like vinyl chloride
• TCE instantly evaporates and leaves no trace
• TCE converts immediately to oxygen under anaerobic conditions
• TCE is converted to harmless water within minutes

Correct Answer: TCE can persist but may be biodegraded reductively to toxic intermediates like vinyl chloride

Q48. Which laboratory practice minimizes worker exposure when using TCE as a solvent?

• Work in a certified chemical fume hood with proper PPE
• Weigh TCE on an open benchtop without a hood
• Use open vessels near mouths to speed evaporation
• Store TCE near food and beverages

Correct Answer: Work in a certified chemical fume hood with proper PPE

Q49. Which physicochemical parameter is most relevant to predicting TCE volatility from water bodies?

• Henry’s law constant
• Optical rotation
• pKa
• Buffer capacity

Correct Answer: Henry’s law constant

Q50. For a B. Pharm student evaluating TCE risks in formulations, the most important consideration is:

• Minimizing residual solvent and ensuring appropriate analytical verification
• Maximizing residual TCE for stability
• Ignoring solvent residues as irrelevant to product safety
• Using TCE as a preservative without limits

Correct Answer: Minimizing residual solvent and ensuring appropriate analytical verification

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