KAPS Pharmaceutical Chemistry and Analysis 2 — Questions and Answers
Question 1: Which spectroscopic technique measures the absorption of infrared radiation to identify functional groups in a drug molecule?
- Mass spectrometry
- Infrared spectroscopy (Correct answer)
- Atomic absorption spectroscopy
- X-ray crystallography
Correct answer: Infrared spectroscopy
Infrared spectroscopy identifies functional groups based on characteristic bond vibration frequencies in the IR region.
Question 2: The Henderson-Hasselbalch equation is used to calculate which property of a drug?
- Melting point
- Molecular weight
- Degree of ionization at a given pH (Correct answer)
- Log P value
Correct answer: Degree of ionization at a given pH
The Henderson-Hasselbalch equation relates pH, pKa, and the ratio of ionized to unionized drug forms.
Question 3: Which type of isomerism occurs when two compounds have the same molecular formula but differ in the connectivity of atoms?
- Stereoisomerism
- Enantiomerism
- Constitutional isomerism (Correct answer)
- Conformational isomerism
Correct answer: Constitutional isomerism
Constitutional (structural) isomers share the same molecular formula but have different atom connectivity.
Question 4: In HPLC, what does the term 'resolution' describe?
- The speed of separation
- The degree of separation between two adjacent peaks (Correct answer)
- The detector sensitivity
- The column temperature
Correct answer: The degree of separation between two adjacent peaks
Resolution quantifies how well two adjacent chromatographic peaks are separated from each other.
Question 5: Which bond type is primarily responsible for the double-helix stability of DNA and is also important in drug-receptor interactions?
- Covalent bonds
- Ionic bonds
- Hydrogen bonds (Correct answer)
- Metallic bonds
Correct answer: Hydrogen bonds
Hydrogen bonds stabilize the DNA double helix between base pairs and are critical in many drug-receptor binding events.
Question 6: The optical rotation of a chiral drug is measured using which instrument?
- Refractometer
- Polarimeter (Correct answer)
- Colorimeter
- Viscometer
Correct answer: Polarimeter
A polarimeter measures the rotation of plane-polarized light by chiral (optically active) substances.
Question 7: Which reagent is commonly used in the Karl Fischer titration method for water determination in pharmaceuticals?
- Potassium permanganate
- Iodine and sulfur dioxide (Correct answer)
- Sodium hydroxide
- Silver nitrate
Correct answer: Iodine and sulfur dioxide
Karl Fischer titration uses iodine and sulfur dioxide (with methanol and pyridine) to react stoichiometrically with water.
KAPS Pharmaceutical Chemistry and Analysis 2
Which spectroscopic technique measures the absorption of infrared radiation to identify functional groups in a drug molecule?