Free Analytical Chemistry MCQs with Answers
105 Analytical Chemistry MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Analytical chemistry identifies and measures substances using separation and instrumental methods. Chromatography is studied through stationary and mobile phases, retention and Rf values, while spectroscopy connects absorption of electromagnetic radiation with molecular structure and supports qualitative and quantitative analysis through techniques such as UV-visible and infrared spectroscopy.
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105 questions · page 11 of 11
101. The functional group region in infra-red spectrum lies between:
- A. 500 - 1300 cm-1
- B. 600 - 1500 cm-1
- C. 1500 - 4000 cm-1
- D. 2500 - 3500 cm-1
Explanation: The functional group region in an infrared spectrum ranges from 1500 to 4000 cm-1. This is where the characteristic absorption peaks of various functional groups, such as -OH, -NH, and C=O, are typically observed. Option A (500 - 1300 cm-1) and Option B (600 - 1500 cm-1) fall within the fingerprint region, which is known for the unique absorption patterns of entire molecules rather than specific functional groups. Option D (2500 - 3500 cm-1) is a subset of the functional group region, but it doesn't cover the entire range where functional groups can be detected, making Option C the most accurate choice.
Correct answer: 1500 - 4000 cm-1102. The infrared spectra commonly referred to as IR spectra is usually expressed as:
- A. Wavelength
- B. Wavenumber
- C. Frequency
- D. All of the above
Explanation: The correct answer is All of the above. Infrared spectra can be expressed in terms of wavelength, wavenumber, or frequency, each offering distinct advantages in different contexts:Wavelength: Useful for comparing spectra from different sources or under varying conditions.Wavenumber: Ideal for calculations related to molecular vibrations, providing a unit independent of sample physical properties.Frequency: Relevant for speed-related calculations of IR radiation.While each unit is valid, the context and specific requirements of the analysis determine the most appropriate choice. Hence, IR spectra are commonly expressed using any of these units.
Correct answer: All of the above103. Which of the following radiations cannot cause excitation in the molecule ?
- A. Red Colour
- B. Green Colour
- C. Ultra Voilet
- D. None of the above
Explanation: The answer is D as all the mentioned radiations can excite molecules.All electromagnetic radiation, including red and green colours of visible light, have the potential to cause excitation in molecules, although the likelihood of excitation increases with higher-energy radiation such as ultraviolet (UV) and X-rays. Therefore, all the options given in the question can cause excitation in molecules to some extent, and hence the correct answer is D) None of the above.
Correct answer: None of the above104. How many types of "NMR" protons are there in Isopropyl chloride?
- A. 2
- B. 6
- C. 4
- D. 8
Explanation: In isopropyl chloride, there are 6 different types of "NMR" protons. This means that there are 6 unique environments for the protons in the molecule, leading to distinct signals in the nuclear magnetic resonance (NMR) spectrum. Each type of proton corresponds to a specific chemical environment within the molecule.
Correct answer: 6105. Which of the following methods, relatively gives more information about the structure of an organic compound:
- A. Mass Spectroscopy
- B. NMR Spectroscopy
- C. IR Spectroscopy
- D. U.V Visible Spectroscopy
Explanation: Among the options provided, NMR (Nuclear Magnetic Resonance) Spectroscopy gives more detailed information about the structure of an organic compound. It provides insights into the connectivity of atoms, the arrangement of functional groups, and the environment around specific nuclei (like hydrogen and carbon). This technique is especially powerful in elucidating the stereochemistry of molecules. Therefore, option b is correct.
Correct answer: NMR Spectroscopy