Unit 4 MCQ Chemistry PDF

unit 4 mcq chemistry 1. UV-Visible Spectroscopy 1. What is the principle of UV-Visible Spectroscopy? a) Absorption of UV and visible light by molecules b) Emission of UV and visible light by molecules c) Transmission of UV and visible light through molecules d) Scattering of UV and visible light b...

unit 4 mcq chemistry 1. UV-Visible Spectroscopy 1. What is the principle of UV-Visible Spectroscopy? a) Absorption of UV and visible light by molecules b) Emission of UV and visible light by molecules c) Transmission of UV and visible light through molecules d) Scattering of UV and visible light by molecules Answer: a) Absorption of UV and visible light by molecules 2. Which law defines the relationship between absorbance and concentration of a solute? a) Coulomb’s Law b) Lambert’s Beer’s Law c) Planck’s Law d) Hooke’s Law Answer: b) Lambert’s Beer’s Law 3. The absorbance of a substance is measured at which point? a) The wavelength at maximum absorbance b) The wavelength at maximum transmittance c) At any random wavelength d) All of the above Answer: a) The wavelength at maximum absorbance 4. The UV-Visible spectrophotometer mainly measures which property of light? a) Intensity b) Frequency c) Wavelength d) Polarization Answer: a) Intensity 5. Which of the following is the main advantage of a double beam spectrophotometer? a) Simultaneous measurement of reference and sample b) Low cost c) Higher wavelength accuracy d) High sensitivity Answer: a) Simultaneous measurement of reference and sample 2. Flame Photometry 6. Flame Photometry is based on the principle of: a) Atomic absorption b) Atomic emission c) UV absorption d) Fluorescence Answer: b) Atomic emission 7. In flame photometry, which part of the flame excites the atoms of the sample? a) Combustion zone b) Photometric zone c) Heating zone d) Ionization zone Answer: a) Combustion zone 8. Which of the following elements can be determined using Flame Photometry? a) Sodium b) Potassium c) Calcium d) All of the above Answer: d) All of the above 9. In Flame Photometry, the intensity of emitted light is proportional to: a) Concentration of the element b) Flame temperature c) Wavelength d) All of the above Answer: a) Concentration of the element 10. What type of lamp is used as a light source in Flame Photometry? a) Incandescent lamp b) Mercury vapor lamp c) Tungsten lamp d) None of the above Answer: d) None of the above (usually a flame or atomic source is used) 3. Chromatography 11. Chromatography is used for: a) Separation of components in a mixture b) Purification of compounds c) Identification of substances d) All of the above Answer: d) All of the above 12. Which of the following is a type of chromatography? a) Thin Layer Chromatography (TLC) b) Gas Chromatography (GC) c) Liquid Chromatography (LC) d) All of the above Answer: d) All of the above 13. What is the stationary phase in Thin Layer Chromatography (TLC)? a) A liquid b) A solid adsorbent c) A gas d) A mixture Answer: b) A solid adsorbent 14. The mobile phase in TLC typically consists of: a) A solid material b) A liquid solvent or mixture of solvents c) A gas d) An electromagnetic field Answer: b) A liquid solvent or mixture of solvents 15. What is the main advantage of Thin Layer Chromatography (TLC)? a) It is highly accurate b) It allows separation of large sample sizes c) It requires minimal sample and is inexpensive d) It provides quantitative analysis Answer: c) It requires minimal sample and is inexpensive 16. What is the typical application of TLC? a) Pharmaceutical analysis b) Food industry analysis c) Environmental monitoring d) All of the above Answer: d) All of the above 17. Which of the following can be used as the mobile phase in TLC? a) Water b) Ethanol c) Acetone d) All of the above Answer: d) All of the above 18. In TLC, the Rf value is calculated as: a) Distance travelled by the solvent / Distance travelled by the sample b) Distance travelled by the sample / Distance travelled by the solvent c) Distance travelled by the sample d) Distance travelled by the solvent Answer: b) Distance travelled by the sample / Distance travelled by the solvent 19. In TLC, a higher Rf value indicates: a) A lower affinity for the stationary phase b) A higher affinity for the stationary phase c) A more polar compound d) A less volatile compound Answer: a) A lower affinity for the stationary phase 4. IR Spectroscopy 20. The principle of IR spectroscopy is based on: a) The absorption of infrared light by molecules b) The emission of infrared light by molecules c) Scattering of infrared light by molecules d) Refraction of infrared light by molecules Answer: a) The absorption of infrared light by molecules 21. Which region of the IR spectrum is typically used for the analysis of organic compounds? a) Near-infrared region b) Mid-infrared region c) Far-infrared region d) Visible region Answer: b) Mid-infrared region 22. What is the typical range of IR radiation? a) 200-400 nm b) 400-800 nm c) 2500-25,000 nm d) 10,000-50,000 nm Answer: c) 2500-25,000 nm 23. Which of the following is a typical application of IR spectroscopy? a) Identification of functional groups b) Quantification of unknown substances c) Determining molecular structure d) All of the above Answer: d) All of the above 24. In IR spectroscopy, which part of the molecule absorbs IR radiation? a) Electrons b) Atomic nuclei c) Vibrational modes of bonds d) All of the above Answer: c) Vibrational modes of bonds 25. A sharp, strong peak around 1700 cm⁻¹ in an IR spectrum is typically indicative of: a) C=O bond b) O-H bond c) C-H bond d) N-H bond Answer: a) C=O bond 26. Which of the following is used as a light source in IR spectroscopy? a) Tungsten lamp b) Mercury vapor lamp c) Globar (silicon carbide) d) Xenon lamp Answer: c) Globar (silicon carbide) 27. In a double-beam IR spectrophotometer, what is the role of the reference beam? a) To compare the absorbance of the sample b) To maintain a constant light intensity c) To calibrate the detector d) To focus the light on the sample Answer: b) To maintain a constant light intensity 28. Which of the following cannot be analyzed by IR spectroscopy? a) Simple inorganic molecules b) Organic compounds c) Polymers d) Mixtures Answer: a) Simple inorganic molecules 29. In IR spectroscopy, which of the following is a characteristic of a broad O-H stretch? a) It appears around 2200 cm⁻¹ b) It appears around 3400-3550 cm⁻¹ c) It appears around 1600 cm⁻¹ d) It appears around 3000 cm⁻¹ Answer: b) It appears around 3400-3550 cm⁻¹ 30. Which detector is commonly used in IR spectroscopy? a) Photomultiplier tube b) Photodiode array c) Thermocouple detector d) Pyroelectric detector Answer: d) Pyroelectric detector General Questions 31. Which technique is commonly used for the analysis of elemental composition? a) UV-Visible Spectroscopy b) Flame Photometry c) Gas Chromatography d) Nuclear Magnetic Resonance (NMR) Answer: b) Flame Photometry 32. Which of the following methods is used for qualitative analysis? a) UV-Visible Spectroscopy b) Flame Photometry c) Chromatography d) All of the above Answer: d) All of the above 33. The primary application of Flame Photometry is in the analysis of: a) Organic compounds b) Inorganic ions c) Proteins d) Peptides Answer: b) Inorganic ions 34. Which of the following solvents is not typically used in TLC? a) Methanol b) Acetone c) Water d) Benzene Answer: c) Water 35. In IR spectroscopy, which of the following functional groups exhibits a strong, sharp absorption around 1750 cm⁻¹? a) C=O (carbonyl) b) O-H (hydroxyl) c) N-H (amine) d) C-H (alkyl) Answer: a) C=O (carbonyl) 36. Which of the following is not typically analyzed by UV-Visible Spectroscopy? a) Proteins b) Nucleic acids c) Organic molecules with conjugated systems d) Noble gases Answer: d) Noble gases 37. What type of light source is typically used in UV-Visible Spectroscopy? a) Deuterium lamp b) Xenon lamp c) Tungsten lamp d) Both a and c Answer: d) Both a and c 38. In Flame Photometry, what is used to convert the emitted light into a measurable signal? a) Spectrophotometer b) Photomultiplier tube c) Flame detector d) Microbalance Answer: b) Photomultiplier tube 39. Which region of the electromagnetic spectrum is most commonly used in IR spectroscopy? a) Ultraviolet b) Visible c) Infrared d) Microwaves Answer: c) Infrared 40. What is the typical sample size required for UV-Visible Spectroscopy? a) Microscopic b) Small volume of liquid (few milliliters) c) Large solid samples d) Any size Answer: b) Small volume of liquid (few milliliters)