13. Which of the following pieces of information can be obtained from colorimetry?

• The relative molecular mass of an unknown compound

• The concentration of a coloured solution

• The structure of a compound

• The functional group(s) present in a compound

Questions 14 and 15 refer to the determination of the concentration of a red food colouring by colorimetry.

14. Which of the following statements about colorimetry are correct?

(1) The sample solution under investigation must be coloured.

(2) Colorimeter is the instrument used in colorimetry.

(3) The calibration curve is plotted by measuring the absorbance of a series of standard solutions of different concentrations.

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

15. The following diagram shows a calibration curve of a red food colouring. If a sample containing an unknown concentration of red food colouring has an absorbance of 0.40, what is the concentration of the red food colouring?

• 3.0 g dm^–3

• 3.5 g dm^–3

• 4.0 g dm^–3

• 4.5 g dm^–3

16. Which of the following pieces of information can be obtained from infrared spectroscopy?

• The relative atomic mass of an element

• The functional group(s) present in an unknown compound

• The empirical formula of an unknown compound

• The structural formula of an unknown compound

17. Consider the following infrared spectrum:

Which of the following compounds gives this spectrum?

• CH₃CH₂CH₃

• CH₃C≡CH

• CH₃CH=CH₂

• CH₃COCH₃

18. Consider the following infrared spectrum:

Which of the following compounds gives the above spectrum?

• Ethyl ethanoate

• Ethanol

• Ethane

• Ethene

19. A student performed an experiment to oxidize propan-1-ol to propanal. By using infrared spectroscopy, how could he check that all propan-1-ol has reacted?

• The presence of absorption peaks at 1680– 1800 cm^–1

• The absence of absorption peaks at 1680– 1800 cm^–1

• The presence of broad absorption peaks at 3230–3670 cm^–1

• The absence of broad absorption peaks at 3230–3670 cm^–1

20. Which of the following pieces of information can be obtained from mass spectrometry?

(1) The relative molecular mass of a molecular compound

(2) The molecular structure of a carbon compound

(3) The relative abundance of isotopes of an element

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

21. Which of the following ions will be deflected to the greatest extent in a mass spectrometer?

• ³⁵Cl⁺

• ³⁷Cl⁺

• ³⁵Cl²⁺

• ³⁷Cl²⁺

22. Which of the following statements concerning the mass spectrum of CH₃Cl is/are correct?

(1) There is a peak generated by the molecular ion at m/e = 50.

(2) There is a peak generated by the molecular ion at m/e = 50.5.

(3) There is a peak generated by the molecular ion at m/e = 52.

• (1) only

• (2) only

• (1) and (3) only

• (2) and (3) only