Basic tests for pharmaceutical substances MCQs With Answer provide essential practice in pharmaceutical analysis, quality control, and pharmacopoeial methods for B.Pharm students. This concise review covers identity tests, purity assays, chromatographic and spectroscopic techniques (TLC, HPLC, UV, IR), limit tests for chloride, sulfate and heavy metals, loss on drying, residue on ignition, melting point, and chemical spot tests for functional groups. Emphasis on assay validation, sample preparation and interpretation of results builds competence in drug analysis, quality assurance, and regulatory compliance. These MCQs strengthen problem-solving for laboratory and exam situations. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the primary purpose of basic tests for pharmaceutical substances?
- To determine color and odor only
- To establish identity, purity and assay of pharmaceutical substances
- To measure only microbial contamination
- To test packaging integrity
Correct Answer: To establish identity, purity and assay of pharmaceutical substances
Q2. Which technique is most specific for confirming functional groups in a drug substance?
- Melting point determination
- Thin layer chromatography (TLC)
- Infrared (IR) spectroscopy
- Loss on drying
Correct Answer: Infrared (IR) spectroscopy
Q3. Which reagent is commonly used in the limit test for chloride in pharmaceutical substances?
- Barium chloride solution
- Silver nitrate solution
- Lead acetate solution
- Potassium permanganate solution
Correct Answer: Silver nitrate solution
Q4. The ferric chloride test is widely used to detect which functional group?
- Amine
- Phenol
- Ester
- Nitrate
Correct Answer: Phenol
Q5. Which stationary phase is most commonly used for routine silica-gel TLC in drug analysis?
- Silica gel
- C18 reversed-phase
- Ion exchange resin
- Polyethylene
Correct Answer: Silica gel
Q6. Which detector is commonly used in HPLC for pharmaceutical compounds with aromatic chromophores?
- Refractive index detector
- UV-Visible detector
- Electrochemical detector
- Flame ionization detector
Correct Answer: UV-Visible detector
Q7. Which assay technique is based on a stoichiometric chemical reaction?
- Titrimetric (titration) assay
- Spectrophotometric assay
- Chromatographic assay
- Gravimetric assay
Correct Answer: Titrimetric (titration) assay
Q8. What does the loss on drying test determine for a pharmaceutical substance?
- Total ash content
- Moisture content (water loss on heating)
- Residual solvents
- Particle size distribution
Correct Answer: Moisture content (water loss on heating)
Q9. What is measured by the residue on ignition (ash) test?
- Organic volatile impurities
- Inorganic residue (total ash) after combustion
- Purity by melting point
- Optical rotation
Correct Answer: Inorganic residue (total ash) after combustion
Q10. A sharp and narrow melting point range of a crystalline drug generally indicates:
- High hygroscopicity
- High purity of the substance
- High microbial contamination
- Presence of heavy metals
Correct Answer: High purity of the substance
Q11. Specific rotation measurement is used to assess what property of a drug substance?
- Optical activity (chirality)
- Molecular weight
- pH
- Surface area
Correct Answer: Optical activity (chirality)
Q12. In a simple qualitative flame test, which color indicates presence of sodium ions?
- Blue
- Yellow
- Crimson
- Violet
Correct Answer: Yellow
Q13. The pharmacopoeial limit test for sulfate ions commonly uses which reagent?
- Silver nitrate
- Barium chloride
- Lead acetate
- Ferric chloride
Correct Answer: Barium chloride
Q14. Which instrument directly measures the hydrogen ion concentration of a pharmaceutical solution?
- Conductivity meter
- pH meter
- Turbidimeter
- Refractometer
Correct Answer: pH meter
Q15. In UV-Visible spectrophotometry, the wavelength at which maximum absorbance occurs is called:
- Retention time
- Lambda max (λmax)
- Baseline
- Absorbance unit
Correct Answer: Lambda max (λmax)
Q16. How is the Rf value in TLC calculated?
- Distance solvent front / distance spot
- Distance spot / distance solvent front
- Distance spot × distance solvent front
- Distance spot − distance solvent front
Correct Answer: Distance spot / distance solvent front
Q17. Which reagent produces a silver mirror with aldehydes (positive identification test)?
- Tollens’ reagent
- Benedict’s reagent
- Biuret reagent
- Ninhydrin reagent
Correct Answer: Tollens’ reagent
Q18. The Griess reagent is used to detect which inorganic impurity in pharmaceutical samples?
- Chloride
- Nitrite
- Sulfate
- Iron
Correct Answer: Nitrite
Q19. Which analytical technique is most suitable for quantifying volatile organic impurities in a drug substance?
- Gas chromatography (GC)
- High performance liquid chromatography (HPLC)
- Thin layer chromatography (TLC)
- Infrared spectroscopy (IR)
Correct Answer: Gas chromatography (GC)
Q20. The Hinsberg test helps distinguish which class of organic compounds?
- Carboxylic acids
- Amines (primary, secondary, tertiary)
- Alcohols
- Ketones
Correct Answer: Amines (primary, secondary, tertiary)
Q21. Which reagent is commonly used as a general test for alkaloids in crude extracts?
- Mayer’s reagent
- Fehling’s solution
- Bromine water
- Schiff reagent
Correct Answer: Mayer’s reagent
Q22. Headspace gas chromatography is especially used for determining which class of impurities?
- Residual solvents
- Heavy metals
- Inorganic anions
- Microbial endotoxins
Correct Answer: Residual solvents
Q23. Which HPLC column type is most commonly used in reversed-phase chromatography for drug analysis?
- Silica gel normal phase
- Cation exchange column
- C18 (octadecylsilane) reversed-phase column
- Size-exclusion column
Correct Answer: C18 (octadecylsilane) reversed-phase column
Q24. The Beer–Lambert law in spectrophotometry relates absorbance to which parameter?
- Particle size distribution
- Concentration of analyte
- Retention time
- Viscosity of solution
Correct Answer: Concentration of analyte
Q25. What is a primary standard in analytical chemistry?
- A reagent with known high purity used to prepare standard solutions
- An in-house sample with unknown purity
- A diluted solution for routine cleaning
- A detector calibration gas
Correct Answer: A reagent with known high purity used to prepare standard solutions
Q26. Which basic test is used to determine particle size distribution of a powdered drug?
- Sieve analysis
- IR spectroscopy
- TLC
- pH measurement
Correct Answer: Sieve analysis
Q27. Which technique identifies compounds by their mass-to-charge ratio (m/z)?
- Infrared spectroscopy (IR)
- Mass spectrometry (MS)
- Ultraviolet-visible spectroscopy (UV-Vis)
- Polarimetry
Correct Answer: Mass spectrometry (MS)
Q28. Decolorization of bromine water is a simple qualitative test for:
- Carboxylic acids
- Unsaturation (double bonds) or phenolic compounds
- Alkaloids
- Proteins
Correct Answer: Unsaturation (double bonds) or phenolic compounds
Q29. Which reagent gives a red complex with ferric ions and is used in iron determination?
- Potassium permanganate
- Potassium thiocyanate
- Sodium nitroprusside
- 1,10-phenanthroline
Correct Answer: Potassium thiocyanate
Q30. Which method is preferred for quantitative determination of residual solvents according to pharmacopeial guidelines?
- Gravimetric analysis
- Headspace gas chromatography (HS-GC)
- Thin layer chromatography (TLC)
- UV spectrophotometry
Correct Answer: Headspace gas chromatography (HS-GC)
