Lesson 4.2.4

4.2.4 Analytical techniques Quiz: OCR Chemistry, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

In partnership with Revision Ninja

Lesson 4.2.4, Analytical techniques: 20 multiple choice questions for the OCR Chemistry (H432), Unit 3: Core organic chemistry, written with Revision Ninja.

Host it live on the board and students join with a game code on their own devices, or revise alone with Free Play. The answers are revealed in the game.

Host this setFree Play

The 20 questions

  1. What effect does infrared radiation have on covalent bonds in molecules?

    • Ionise completely
    • Break heterolytically
    • Vibrate more
    • Rotate freely

  2. Which two absorption peaks in an IR spectrum identify a carboxylic acid?

    • C=O and C-H
    • C=C and O-H
    • O-H and C-N
    • C=O and O-H

  3. Which broad IR absorption peak is used to identify an alcohol?

    • C-H bond peak
    • C-O bond peak
    • O-H bond peak
    • C=O bond peak

  4. Which bond causes the IR absorption peak found at approximately 3000 cm⁻¹ in most organic compounds?

    • C-C bond
    • C=O bond
    • C-H bond
    • O-H bond

  5. What quantity does the mass-to-charge ratio of the molecular ion peak give?

    • Molar gas volume
    • Relative molecular mass
    • Empirical formula mass
    • Relative atomic mass

  6. A small M+1 peak in a mass spectrum of an organic compound is mainly caused by which isotope?

    • Hydrogen-2 (deuterium)
    • Carbon-13
    • Oxygen-18
    • Nitrogen-15

  7. Which gas in the atmosphere absorbs infrared radiation through its C-H bonds and contributes to global warming?

    • Argon, Ar
    • Methane, CH4
    • Nitrogen, N2
    • Oxygen, O2

  8. The molecular ion peak of a compound appears at m/z = 46. What is the relative molecular mass of the compound?

    • 47
    • 46
    • 92
    • 45

  9. A mass spectrum of an unknown organic compound shows a fragment at m/z = 15. Which ion is most likely responsible?

    • CO+
    • CH3+
    • C2H5+
    • COOH+

  10. A compound has 6 carbon atoms. Approximately what is the size of its M+1 peak relative to its M peak?

    • About 11 per cent
    • About 0.6 per cent
    • About 6.6 per cent
    • About 1.1 per cent

  11. A compound is found by elemental analysis to contain 40.0% C, 6.7% H and 53.3% O by mass. What is its empirical formula?

    • C2H4O2
    • C2H5O
    • CH2O
    • CHO

  12. An IR spectrum has absorptions at 2500–3300 cm⁻¹ and 1710 cm⁻¹. Which functional group is present?

    • Ester
    • Alcohol
    • Aldehyde
    • Carboxylic acid

  13. A compound with Mr 88 shows a strong IR absorption near 1740 cm^-1 but no broad O-H absorption. Which functional group is most likely present?

    • An ester
    • A primary alcohol
    • A carboxylic acid
    • An amine

  14. An IR spectrum of a compound shows only a broad absorption between 3200 and 3550 cm^-1 and no C=O absorption. Which type of compound is most likely?

    • An alcohol
    • An aldehyde
    • A carboxylic acid
    • A ketone

  15. Why can carbon monoxide and nitrogen monoxide pollutants in exhaust fumes be detected using IR spectroscopy?

    • Ions scatter radiation
    • Gases are coloured
    • Bonds absorb IR
    • Molecules emit IR

  16. A compound has a molecular ion peak at m/z = 58 and a strong IR absorption at about 1715 cm^-1 with no O-H absorption. Which compound fits best?

    • Propanone, CH3COCH3
    • Propan-1-ol, CH3CH2CH2OH
    • Propan-2-ol, CH3CH(OH)CH3
    • Propenoic acid, CH2=CHCOOH

  17. Which isotope causes the M+1 peak in an organic mass spectrum?

    • Carbon-14
    • Carbon-12
    • Carbon-13
    • Hydrogen-2

  18. What chemical formula is determined directly from elemental analysis percentage data?

    • Molecular formula
    • Displayed formula
    • Empirical formula
    • Structural formula

  19. Which wavenumber range is typical for the C=O absorption in an IR spectrum?

    • About 1680-1750 cm^-1
    • About 3200-3550 cm^-1
    • About 600-800 cm^-1
    • About 2100-2260 cm^-1

  20. A compound contains 85.7% carbon and 14.3% hydrogen by mass. What is its empirical formula?

    • C2H4
    • CH
    • CH2
    • C3H7

All OCR Chemistry quizzes