Structure and uses of BHC MCQs With Answer

Structure and uses of BHC MCQs With Answer is an essential study module for B. Pharm students focusing on benzene hexachloride (BHC or HCH) chemistry, stereochemistry, pharmacological actions, toxicology and environmental impact. This concise introduction emphasizes key concepts: molecular formula, isomerism (alpha, beta, gamma/lindane), mechanism of action on GABA receptors, therapeutic topical uses, analytical detection (GC-ECD/G C-MS), persistence, bioaccumulation and regulatory restrictions. Targeted keywords such as BHC, HCH, lindane, structure, uses, toxicity, environmental persistence and analytical methods are integrated to aid exam preparation and SEO visibility. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the molecular formula of BHC (benzene hexachloride / HCH)?

• C6H6Cl6
• C6H12Cl6
• C6Cl6
• C6H6Cl2

Correct Answer: C6H6Cl6

Q2. In pesticide and pharmaceutical literature, BHC is synonymous with which compound name?

• Hexachlorocyclohexane (HCH)
• Hexachlorobenzene (HCB)
• Hexachloroethane (HCE)
• Chlorobenzene

Correct Answer: Hexachlorocyclohexane (HCH)

Q3. Which HCH isomer is commonly known as lindane and is the primary insecticidal isomer?

• Alpha-HCH
• Beta-HCH
• Gamma-HCH
• Delta-HCH

Correct Answer: Gamma-HCH

Q4. The structure of BHC consists of which core ring with chlorine substituents?

• Benzene ring with six chlorines
• Cyclohexane ring with six chlorines
• Cyclopentane ring with five chlorines
• Hexane chain with six chlorines

Correct Answer: Cyclohexane ring with six chlorines

Q5. How many stereoisomers are typically described for hexachlorocyclohexane (HCH)?

• Three
• Five
• Eight
• Sixteen

Correct Answer: Eight

Q6. What is the primary pharmacological mechanism by which lindane exerts insecticidal and toxic effects?

• Activation of acetylcholine receptors
• Antagonism of GABA-gated chloride channels
• Inhibition of monoamine oxidase
• Blocking voltage-gated sodium channels

Correct Answer: Antagonism of GABA-gated chloride channels

Q7. Which clinical dermatological uses have lindane formulations historically served?

• Topical antibiotic for impetigo
• Topical antihistamine for urticaria
• Topical scabicide and pediculicide
• Topical antifungal for tinea infections

Correct Answer: Topical scabicide and pediculicide

Q8. Which analytical technique is most commonly used for sensitive detection of BHC isomers in biological and environmental samples?

• Ultraviolet-visible spectrophotometry
• Gas chromatography with electron capture detector (GC-ECD)
• Ion-selective electrode analysis
• Gravimetric titration

Correct Answer: Gas chromatography with electron capture detector (GC-ECD)

Q9. Which BHC isomer is known to be the most environmentally persistent and prone to bioaccumulation?

• Alpha-HCH
• Beta-HCH
• Gamma-HCH
• Delta-HCH

Correct Answer: Beta-HCH

Q10. Which property of BHC best explains its tendency to bioaccumulate in adipose tissue?

• High water solubility
• High lipophilicity (hydrophobicity)
• High volatility
• Strong ionic character

Correct Answer: High lipophilicity (hydrophobicity)

Q11. Technical BHC preparations typically contain which predominant isomer by proportion?

• Predominantly gamma-HCH
• Predominantly alpha-HCH
• Predominantly delta-HCH
• Pure beta-HCH only

Correct Answer: Predominantly alpha-HCH

Q12. Which organ is primarily responsible for hepatic metabolism of lindane in humans?

• Kidney
• Liver
• Lungs
• Skin

Correct Answer: Liver

Q13. The main elimination route for BHC and its metabolites in humans is via which pathway?

• Exhalation as unchanged gas
• Urinary excretion only
• Biliary secretion and fecal elimination
• Excretion through sweat glands

Correct Answer: Biliary secretion and fecal elimination

Q14. Occupational exposure to BHC most commonly results from which route of entry?

• Oral ingestion of tablets
• Dermal absorption and inhalation of aerosols
• Intravenous injection
• Ingestion via breastfeeding only

Correct Answer: Dermal absorption and inhalation of aerosols

Q15. Which patient population should avoid lindane-containing topical products due to increased risk of neurotoxicity?

• Patients with heart disease
• Patients with seizure disorders
• Patients with hypertension
• Patients with hyperthyroidism

Correct Answer: Patients with seizure disorders

Q16. What is a primary clinical manifestation of acute lindane poisoning?

• Hypotension without neurological signs
• Respiratory paralysis only
• Neurological excitation progressing to tremors and seizures
• Severe allergic dermatitis only

Correct Answer: Neurological excitation progressing to tremors and seizures

Q17. Which environmental degradation pathway contributes to transformation of HCH isomers in anaerobic soils?

• Photolysis only
• Anaerobic reductive dechlorination by microbes
• Hydrolysis by water alone
• Complete mineralization to CO2 within days

Correct Answer: Anaerobic reductive dechlorination by microbes

Q18. Which detector paired with gas chromatography gives high selectivity for organochlorine insecticides like BHC?

• Flame ionization detector (FID)
• Electron capture detector (ECD)
• Refractive index detector (RID)
• Turbidimetric detector

Correct Answer: Electron capture detector (ECD)

Q19. Which characteristic is true for lindane formulations used in medicine?

• Oral tablet formulations are standard
• Topical lotions and shampoos are common
• Intravenous injections are routine
• Nasal sprays are recommended

Correct Answer: Topical lotions and shampoos are common

Q20. Which statement best describes global regulatory trends for lindane (gamma-HCH)?

• Widely promoted as first-line systemic therapy
• Banned or restricted in many countries due to persistence and toxicity
• Unregulated and considered completely safe
• Required in all agricultural crops worldwide

Correct Answer: Banned or restricted in many countries due to persistence and toxicity

Q21. Which HCH isomer is most associated with long-term storage in fat and prolonged human body burden?

• Gamma-HCH
• Alpha-HCH
• Beta-HCH
• Delta-HCH

Correct Answer: Beta-HCH

Q22. A primary reason lindane can cause seizures is its antagonistic effect on which inhibitory neurotransmitter system?

• Serotonergic transmission
• GABAergic chloride influx
• Noradrenergic reuptake
• Dopaminergic signaling

Correct Answer: GABAergic chloride influx

Q23. Which sampling matrix is frequently analyzed to assess human exposure to BHC in biomonitoring studies?

• Urine with rapid excretion of unchanged BHC
• Blood/plasma and adipose tissue for persistent residues
• Exhaled breath condensate only
• Hair exclusively

Correct Answer: Blood/plasma and adipose tissue for persistent residues

Q24. Which physical-chemical property makes BHC amenable to long-range environmental transport?

• High water solubility
• High vapor pressure and semi-volatility combined with lipophilicity
• Strong ionic charge in water
• Rapid biodegradability

Correct Answer: High vapor pressure and semi-volatility combined with lipophilicity

Q25. Which of the following best describes the production route for technical BHC?

• Electrophilic aromatic substitution on phenol
• Photochemical or radical chlorination/addition to benzene producing HCH isomers
• Direct chlorination of methane only
• Synthesis from polychlorinated biphenyl precursors

Correct Answer: Photochemical or radical chlorination/addition to benzene producing HCH isomers

Q26. What is the recommended general approach to management of acute lindane-induced seizures?

• Administration of stimulants to counteract CNS depression
• No treatment needed; spontaneous resolution is guaranteed
• Supportive care and rapid control of seizures with benzodiazepines
• Immediate exchange transfusion only

Correct Answer: Supportive care and rapid control of seizures with benzodiazepines

Q27. Which statement about technical BHC mixture vs purified lindane is correct?

• Technical BHC is enriched in gamma isomer only
• Technical BHC is a mixture of several isomers; lindane is the purified gamma isomer
• They are chemically identical preparations
• Technical BHC contains only beta isomer

Correct Answer: Technical BHC is a mixture of several isomers; lindane is the purified gamma isomer

Q28. Which bioremediation strategy is most applicable for treatment of HCH-contaminated soils?

• Aerobic biodegradation is always rapid and complete
• Use of reductive dechlorinating microbes under anaerobic conditions
• Simple dilution in surface water
• Bioremediation is ineffective for organochlorines

Correct Answer: Use of reductive dechlorinating microbes under anaerobic conditions

Q29. Which human health concern is associated with chronic low-level exposure to HCH isomers?

• Only acute gastrointestinal irritation
• Potential neurodevelopmental effects and endocrine disruption
• Guaranteed immunity to insect bites
• Instant permanent skin depigmentation

Correct Answer: Potential neurodevelopmental effects and endocrine disruption

Q30. Which analytical preparation solvent is commonly used to extract BHC residues from environmental samples for GC analysis?

• Water
• n-Hexane or dichloromethane (non-polar organic solvents)
• Acetic acid
• Ethanol-water mixture only

Correct Answer: n-Hexane or dichloromethane (non-polar organic solvents)

Q31. Which class of insecticides does BHC/lindane belong to?

• Organophosphate insecticides
• Carbamate insecticides
• Organochlorine insecticides
• Pyrethroid insecticides

Correct Answer: Organochlorine insecticides

Q32. Which isomer of HCH is typically least volatile and most likely to persist in soils and sediments?

• Alpha-HCH
• Beta-HCH
• Gamma-HCH
• Gamma-HCH is least persistent

Correct Answer: Beta-HCH

Q33. Why is monitoring of BHC residues important in pharmaceutical contexts?

• BHC has no biological effects
• Residual BHC in formulations can pose toxicity risks and residual contamination concerns
• To ensure BHC enhances drug efficacy
• Monitoring is unnecessary due to rapid degradation in formulations

Correct Answer: Residual BHC in formulations can pose toxicity risks and residual contamination concerns

Q34. Which international instrument addresses persistent organic pollutants that include organochlorine pesticides?

• The Montreal Protocol
• The Stockholm Convention on Persistent Organic Pollutants
• The Kyoto Protocol
• The Hague Convention

Correct Answer: The Stockholm Convention on Persistent Organic Pollutants

Q35. In formulation science, why must lindane be used with caution in topical products?

• Because it is water-soluble and washes off immediately
• Because of dermal absorption, systemic toxicity and low therapeutic index
• Because it is inert and ineffective topically
• Because it converts to harmless products on skin contact

Correct Answer: Because of dermal absorption, systemic toxicity and low therapeutic index

Q36. Which laboratory method provides both qualitative and quantitative confirmation of HCH isomers?

• TLC without standards
• GC-MS (gas chromatography–mass spectrometry)
• Paper chromatography only
• Colorimetric strip test

Correct Answer: GC-MS (gas chromatography–mass spectrometry)

Q37. Which factor most contributes to inter-isomer differences in toxicity among HCH stereoisomers?

• Differences in chlorine atomic number
• Differences in three-dimensional stereochemistry and receptor interactions
• Differences in metal content
• Differences in protein content

Correct Answer: Differences in three-dimensional stereochemistry and receptor interactions

Q38. Which occupational control measure is most effective to reduce dermal exposure to BHC in manufacturing settings?

• Wearing impermeable gloves and protective clothing
• Using only sunglasses
• Relying solely on ventilation without PPE
• Wearing cotton gloves only

Correct Answer: Wearing impermeable gloves and protective clothing

Q39. Which of the following statements about lindane and pregnancy is most appropriate for pharmacists to counsel on?

• Lindane is recommended as a first-line systemic therapy during pregnancy
• Lindane should be used with caution; it may be avoided in pregnancy unless benefits outweigh risks
• Lindane has no ability to cross the placenta
• There are no safety considerations for use in pregnancy

Correct Answer: Lindane should be used with caution; it may be avoided in pregnancy unless benefits outweigh risks

Q40. For regulatory compliance, which agency or standard commonly sets maximum residue limits (MRLs) for pesticides in food?

• Codex Alimentarius
• World Meteorological Organization
• International Olympic Committee
• National Highway Traffic Safety Administration

Correct Answer: Codex Alimentarius

Q41. Which structural description correctly reflects the chlorine substituent pattern on HCH ring carbons?

• All six chlorines are equivalent due to high symmetry in all isomers
• Chlorine substituents occupy axial or equatorial positions creating distinct stereochemistry
• Chlorines attach as side chains off a benzene double bond
• Chlorines are not covalently bound in HCH

Correct Answer: Chlorine substituents occupy axial or equatorial positions creating distinct stereochemistry

Q42. Which statement about resistance to BHC in insect populations is correct?

• Resistance cannot develop to organochlorines
• Resistance may develop via enhanced metabolic detoxification or target-site changes
• Resistance is solely due to changes in water availability
• Resistance always makes insects more susceptible to BHC

Correct Answer: Resistance may develop via enhanced metabolic detoxification or target-site changes

Q43. Which environmental compartment often acts as a long-term reservoir for BHC contamination?

• Air only for a few hours
• Soil and sediment due to sorption and persistence
• Surface water with immediate breakdown
• Glass surfaces only

Correct Answer: Soil and sediment due to sorption and persistence

Q44. Which clinical laboratory finding might be monitored in suspected chronic lindane exposure?

• Blood glucose trending only
• Liver function tests and neurological assessment
• Serum sodium only
• Urinary ketones only

Correct Answer: Liver function tests and neurological assessment

Q45. Disposal of BHC-contaminated wastes should preferably be performed by which method to minimize environmental release?

• Open dumping on land
• High-temperature incineration with appropriate scrubbing
• Pouring into municipal sewers
• Dilution in rivers

Correct Answer: High-temperature incineration with appropriate scrubbing

Q46. Which pharmacokinetic property explains why lindane residues can persist in humans long after exposure?

• Rapid renal clearance
• Extensive distribution into adipose tissue and slow release
• Immediate metabolic conversion to CO2
• Excretion unchanged in sweat

Correct Answer: Extensive distribution into adipose tissue and slow release

Q47. Which precaution should pharmacists emphasize to patients using topical lindane products?

• Apply liberally to large open wounds
• Avoid excessive skin exposure, follow label directions and avoid use on inflamed skin or near mucous membranes
• Use daily systemic doses in addition to topical therapy
• Ingest a portion to improve efficacy

Correct Answer: Avoid excessive skin exposure, follow label directions and avoid use on inflamed skin or near mucous membranes

Q48. Which co-exposure scenario can increase the risk of lindane neurotoxicity?

• Concurrent use of anticonvulsants only
• Co-exposure with other neurotoxicants or agents that lower seizure threshold
• Exposure to vitamin supplements only
• Concurrent topical emollients always reduce toxicity

Correct Answer: Co-exposure with other neurotoxicants or agents that lower seizure threshold

Q49. Which statement best describes why gamma-HCH (lindane) was historically favored over technical BHC in medical use?

• Gamma-HCH is the least insecticidal isomer but the cheapest
• Gamma-HCH (lindane) is the most insecticidal isomer and was purified for therapeutic use
• Technical BHC is a single pure compound superior to lindane
• Gamma-HCH is nontoxic and inert

Correct Answer: Gamma-HCH (lindane) is the most insecticidal isomer and was purified for therapeutic use

Q50. For a B. Pharm student, which concept is most critical when studying BHC for safe pharmaceutical practice?

• Only the chemical name matters; therapeutic considerations are irrelevant
• Understanding stereochemistry, toxicology, routes of exposure, safe formulation and regulatory restrictions
• Assuming all organochlorines are interchangeable and safe
• Focusing solely on odor and color of the compound

Correct Answer: Understanding stereochemistry, toxicology, routes of exposure, safe formulation and regulatory restrictions

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