Structure and uses of ethyl chloride MCQs With Answer

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This set of 50 multiple-choice questions on the structure and uses of ethyl chloride MCQs with answer is tailored for B. Pharm students seeking deeper mastery. Covering ethyl chloride (chloroethane) molecular structure, bonding, physical properties, synthesis routes, reaction mechanisms (SN2, radical processes), analytical identification (GC, NMR, IR), pharmaceutical and industrial uses, and safety/handling, these MCQs integrate medicinal chemistry, pharmacology, and laboratory aspects. Questions emphasize conceptual reasoning, problem-solving, and exam readiness with focused attention on reagents, mechanisms, spectral interpretation, and regulatory precautions relevant to ethyl chloride. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the molecular formula of ethyl chloride (chloroethane)?

  • C2H5Cl
  • C2H4Cl2
  • C3H7Cl
  • CH3Cl

Correct Answer: C2H5Cl

Q2. Which structural formula correctly represents ethyl chloride?

  • Cl-CH2-CH3
  • CH3-CH2-Cl
  • Both Cl-CH2-CH3 and CH3-CH2-Cl
  • CH2=CH-Cl

Correct Answer: Both Cl-CH2-CH3 and CH3-CH2-Cl

Q3. What is the approximate molar mass of ethyl chloride?

  • 46.07 g/mol
  • 64.51 g/mol
  • 78.11 g/mol
  • 50.49 g/mol

Correct Answer: 64.51 g/mol

Q4. Which hybridization state does the carbon bonded to chlorine in ethyl chloride exhibit?

  • sp
  • sp2
  • sp3
  • sp3d

Correct Answer: sp3

Q5. What is the approximate boiling point of ethyl chloride at atmospheric pressure?

  • 12 °C
  • 78 °C
  • −24 °C
  • 40 °C

Correct Answer: 12 °C

Q6. Which type of NMR proton splitting pattern is expected for the CH3 group in ethyl chloride?

  • Singlet
  • Triplet
  • Quartet
  • Multiplet with large coupling to chlorine

Correct Answer: Triplet

Q7. Where does the CH2 group adjacent to chlorine typically appear in 1H NMR for ethyl chloride?

  • ~0.9 ppm
  • ~1.2 ppm
  • ~3.4 ppm
  • ~7.2 ppm

Correct Answer: ~3.4 ppm

Q8. Which IR absorption is characteristic of the C–Cl bond in ethyl chloride?

  • ~1700 cm−1 (C=O stretch)
  • ~3000 cm−1 (C–H stretch)
  • ~700–800 cm−1 (C–Cl stretch)
  • ~2200 cm−1 (C≡N stretch)

Correct Answer: ~700–800 cm−1 (C–Cl stretch)

Q9. Which reaction mechanism is most likely for nucleophilic substitution on ethyl chloride under typical conditions?

  • SN1
  • SN2
  • E1
  • Electrophilic aromatic substitution

Correct Answer: SN2

Q10. Ethyl chloride formation from ethanol and HCl typically requires which catalyst or reagent to proceed efficiently?

  • Pd/C
  • ZnCl2 (Lucas reagent)
  • Grignard reagent
  • H2SO4 only

Correct Answer: ZnCl2 (Lucas reagent)

Q11. Industrial synthesis of ethyl chloride commonly involves addition of HCl to which feedstock?

  • Ethylene
  • Propane
  • Methanol
  • Acetylene

Correct Answer: Ethylene

Q12. Which property makes ethyl chloride a volatile topical anesthetic historically used in minor procedures?

  • High water solubility
  • Rapid evaporation producing cooling and local numbness
  • Strong analgesic receptor agonism
  • High boiling point

Correct Answer: Rapid evaporation producing cooling and local numbness

Q13. Ethyl chloride is classified primarily as which hazard in the laboratory?

  • Oxidizer
  • Flammable and volatile inhalation hazard
  • Strong corrosive acid
  • Non-hazardous solvent

Correct Answer: Flammable and volatile inhalation hazard

Q14. Reaction of ethyl chloride with aqueous AgNO3 is a classical test for halide type. What is the expected result compared to tertiary alkyl halides?

  • Immediate precipitate formation like tertiary halides
  • No reaction or very slow reaction due to primary nature
  • Formation of silver chloride gas
  • Formation of an insoluble silver ether

Correct Answer: No reaction or very slow reaction due to primary nature

Q15. Which reagent will convert ethyl chloride to ethanol via nucleophilic substitution?

  • KCN
  • NaOH (aqueous)
  • LiAlH4
  • PBr3

Correct Answer: NaOH (aqueous)

Q16. Reaction of ethyl chloride with KCN primarily yields which organic product?

  • Ethyl alcohol
  • Propionitrile (ethyl cyanide)
  • Ethene
  • Acetaldehyde

Correct Answer: Propionitrile (ethyl cyanide)

Q17. Which of the following best describes ethyl chloride’s solubility in water?

  • Completely miscible
  • Highly soluble (over 500 g/L)
  • Poorly soluble (limited solubility)
  • Reacts vigorously with water

Correct Answer: Poorly soluble (limited solubility)

Q18. Which statement about the polarity of ethyl chloride is correct?

  • It is highly polar and miscible with water
  • It is nonpolar and insoluble in most organics
  • It is moderately polar due to the C–Cl bond but still lipophilic
  • It is ionic

Correct Answer: It is moderately polar due to the C–Cl bond but still lipophilic

Q19. In free radical chlorination of ethane, which product is formed primarily?

  • Ethyl chloride (chloroethane)
  • Chloroform
  • Chloroacetone
  • 1,2-Dichloroethane

Correct Answer: Ethyl chloride (chloroethane)

Q20. Which reagent and condition favor elimination (E2) from ethyl chloride to give ethylene?

  • Weak nucleophile at low temperature
  • Strong base like KOH (high temperature)
  • HCl in water
  • Neutral aqueous ethanol

Correct Answer: Strong base like KOH (high temperature)

Q21. Which analytical technique is most suitable for quantifying ethyl chloride in a pharmaceutical solvent residue study?

  • Infrared spectroscopy (IR) only
  • Gas chromatography (GC) with appropriate detector
  • Thin-layer chromatography (TLC)
  • Polarimetry

Correct Answer: Gas chromatography (GC) with appropriate detector

Q22. The carbon–chlorine bond in ethyl chloride has what approximate bond polarity?

  • Highly polarized with positive chlorine
  • Moderately polarized with δ+ on carbon and δ− on chlorine
  • Nonpolar covalent
  • Ionic bond with Cl−

Correct Answer: Moderately polarized with δ+ on carbon and δ− on chlorine

Q23. Why is ethyl chloride less likely to undergo SN1 substitution compared to tertiary alkyl halides?

  • Because primary carbocations are unstable
  • Because chloride is a poor leaving group
  • Because ethyl chloride is aromatic
  • Because SN1 requires radical initiators

Correct Answer: Because primary carbocations are unstable

Q24. Which safety precaution is most important when handling ethyl chloride in the laboratory?

  • Store in open containers to dissipate vapors
  • Use in a well-ventilated fume hood and avoid ignition sources
  • Mix with strong oxidizers for safe disposal
  • Always heat to boiling before disposal

Correct Answer: Use in a well-ventilated fume hood and avoid ignition sources

Q25. Ethyl chloride acts as which kind of reagent in Friedel–Crafts alkylation?

  • Strong electrophile without catalyst
  • Typical alkyl halide that can form carbocation with Lewis acid catalyst like AlCl3
  • Deactivating agent for aromatic rings
  • Lewis base

Correct Answer: Typical alkyl halide that can form carbocation with Lewis acid catalyst like AlCl3

Q26. Which environmental concern is associated with widespread release of ethyl chloride?

  • Ozone depletion (major contributor)
  • Direct contribution to global warming as a greenhouse gas
  • VOC emission contributing to ground-level ozone and smog
  • Heavy metal contamination

Correct Answer: VOC emission contributing to ground-level ozone and smog

Q27. Which product results from the reaction of ethyl chloride with magnesium in dry ether?

  • Ethyl alcohol
  • Ethylmagnesium chloride (a Grignard reagent)
  • Ethene
  • Magnesium chloride salt only

Correct Answer: Ethylmagnesium chloride (a Grignard reagent)

Q28. Which of the following best describes the stereochemistry of nucleophilic substitution (SN2) on ethyl chloride?

  • Racemization at the reactive center
  • Retention of configuration
  • Inversion of configuration at the reactive carbon (if chiral)
  • Formation of planar carbocation intermediate

Correct Answer: Inversion of configuration at the reactive carbon (if chiral)

Q29. Which pharmaceutical application historically involved ethyl chloride?

  • Systemic oral antibiotic
  • Topical vapocoolant anesthetic
  • Long-acting inhalational anesthetic for surgery
  • Oral antacid

Correct Answer: Topical vapocoolant anesthetic

Q30. Which physical property explains ethyl chloride’s rapid cooling effect when sprayed on skin?

  • High heat capacity
  • Low vapor pressure
  • High enthalpy of vaporization and volatility
  • Strong endothermic dissolution in water

Correct Answer: High enthalpy of vaporization and volatility

Q31. In mass spectrometry, the molecular ion peak (M+) for ethyl chloride will be approximately at which m/z value for the most abundant isotope combination?

  • 46
  • 64
  • 78
  • 35

Correct Answer: 64

Q32. Reaction of ethyl chloride with silver nitrate in ethanol proceeds faster if the mechanism goes through which intermediate?

  • Free radical
  • Carbocation
  • Carbanion
  • Diels–Alder adduct

Correct Answer: Carbocation

Q33. The presence of which substituent on ethyl chloride would increase the rate of SN1 reactions substantially?

  • Electron-donating alkyl groups to form tertiary center
  • Electron-withdrawing halogens on the same carbon
  • Replacement of chlorine with fluorine
  • Replacing ethyl with methyl

Correct Answer: Electron-donating alkyl groups to form tertiary center

Q34. Which reagent selectively replaces chlorine in ethyl chloride with a thiolate to give an ethyl thioether?

  • NaSH in ethanol
  • KMnO4 in water
  • H2, Pd/C
  • OsO4

Correct Answer: NaSH in ethanol

Q35. When stored, ethyl chloride should be kept in which type of container?

  • Open beaker at room temperature
  • Flammable liquids cabinet in tightly closed containers away from heat
  • Direct sunlight to prevent freezing
  • Mixed with oxidizers to stabilize

Correct Answer: Flammable liquids cabinet in tightly closed containers away from heat

Q36. Which of the following reactions will convert ethyl chloride to ethyl acetate (via two steps)?

  • Reaction with NaOH then acidification
  • Reaction with KCN then hydrolysis
  • Formation of Grignard reagent then reaction with CO2 followed by esterification
  • Direct oxidation with KMnO4 to ester

Correct Answer: Formation of Grignard reagent then reaction with CO2 followed by esterification

Q37. Which gas-phase process may lead to formation of ethyl chloride in the atmosphere?

  • Photochemical reaction of ethylene with chlorine radicals
  • Direct emission from volcanic activity
  • Conversion of methane by ozone
  • Oxidation of CO2

Correct Answer: Photochemical reaction of ethylene with chlorine radicals

Q38. Which factor most increases the reactivity of ethyl chloride toward SN2 nucleophiles?

  • Steric hindrance at the α-carbon
  • Polar aprotic solvent to enhance nucleophilicity
  • Presence of excess water
  • High concentration of weak base

Correct Answer: Polar aprotic solvent to enhance nucleophilicity

Q39. In qualitative analysis, which halide gives the most rapid precipitation with AgNO3, and how does ethyl chloride compare?

  • Fluoride is fastest; ethyl chloride reacts faster than fluoride
  • Bromide is fastest; ethyl chloride reacts similarly
  • Chloride precipitates moderately fast; ethyl chloride (alkyl chloride) is slower due to primary nature
  • Iodide is slowest; ethyl chloride reacts fastest

Correct Answer: Chloride precipitates moderately fast; ethyl chloride (alkyl chloride) is slower due to primary nature

Q40. Which product results from hydrolysis of ethyl chloride under strongly acidic conditions?

  • Ethyl chloride remains unchanged
  • Ethyl alcohol (ethanol)
  • Ethyl chloride oxidizes to acetic acid
  • Chloroacetic acid

Correct Answer: Ethyl alcohol (ethanol)

Q41. Which statement about ethyl chloride toxicity is correct?

  • It is non-toxic at any exposure level
  • High inhalation exposure can cause CNS depression and cardiac sensitization
  • It causes immediate severe burns on skin contact
  • It is a strong mutagen at trace concentrations

Correct Answer: High inhalation exposure can cause CNS depression and cardiac sensitization

Q42. In synthetic organic chemistry, ethyl chloride is commonly used as which of the following?

  • Nucleophile in SN2 reactions where ethyl group is transferred
  • Electrophilic alkylating agent under activation
  • Oxidizing agent
  • Chelating ligand

Correct Answer: Electrophilic alkylating agent under activation

Q43. Which laboratory method is most appropriate to remove traces of ethyl chloride from glassware before sensitive assays?

  • Rinse with water only
  • Evaporate under fume hood and solvent exchange with a higher-boiling inert solvent followed by drying
  • Soak in concentrated HCl
  • Immediate flame sterilization

Correct Answer: Evaporate under fume hood and solvent exchange with a higher-boiling inert solvent followed by drying

Q44. Which structural feature explains why ethyl chloride is achiral?

  • It has a plane of symmetry through the C–Cl bond
  • Both carbons are sp hybridized
  • The carbon bearing chlorine is bonded to two identical hydrogen atoms making it not stereogenic
  • Presence of a double bond enforces achirality

Correct Answer: The carbon bearing chlorine is bonded to two identical hydrogen atoms making it not stereogenic

Q45. A student observes in 13C NMR two carbon signals for ethyl chloride. Which chemical shift regions correspond to CH3 and CH2Cl carbons respectively?

  • CH3 ~15–25 ppm; CH2Cl ~40–50 ppm
  • CH3 ~60–80 ppm; CH2Cl ~170–180 ppm
  • CH3 ~100–120 ppm; CH2Cl ~150–160 ppm
  • CH3 ~200–220 ppm; CH2Cl ~0–10 ppm

Correct Answer: CH3 ~15–25 ppm; CH2Cl ~40–50 ppm

Q46. Ethyl chloride can act as a precursor to which carboxylic acid after oxidation and hydrolysis steps?

  • Acetic acid
  • Benzoic acid
  • Formic acid
  • Propionic acid

Correct Answer: Acetic acid

Q47. Which reagent will convert ethyl chloride to ethane via reduction?

  • H2 with Pd/C catalysis
  • NaBH4 in methanol
  • LiAlH4 in dry ether
  • Zn dust and acid (reductive dehalogenation)

Correct Answer: Zn dust and acid (reductive dehalogenation)

Q48. Which factor differentiates reactivity of ethyl chloride from ethyl bromide in SN2 reactions?

  • Ethyl chloride has a better leaving group than bromide
  • Ethyl bromide is typically more reactive due to a weaker C–Br bond and better leaving group
  • Both have identical reactivity always
  • Ethyl chloride is more polar and therefore always faster

Correct Answer: Ethyl bromide is typically more reactive due to a weaker C–Br bond and better leaving group

Q49. Which occupational exposure control is most effective to limit worker inhalation of ethyl chloride in manufacturing?

  • Personal cooling vests
  • Local exhaust ventilation and closed systems
  • Wearing cotton lab coats only
  • Storing in open drums in the work area

Correct Answer: Local exhaust ventilation and closed systems

Q50. In a retrosynthetic analysis, ethyl chloride is a suitable alkylating agent to introduce which fragment into a molecule?

  • Phenyl fragment
  • Ethyl fragment (–CH2CH3)
  • Isopropyl fragment
  • Vinyl fragment

Correct Answer: Ethyl fragment (–CH2CH3)

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