Mass Spectrometry Practice Questions PDF - WJEC

WJEC Okay, here are 20 multiple-choice questions based on the provided knowledge base documents, focusing on the mass spectrometer and relative atomic mass (Ar) calculations: Questions 1. What is the "m/z" value in mass spectrometry an abbreviation for? * (A) Mass * (B) Mass to size ratio * (C) Ma...

WJEC Okay, here are 20 multiple-choice questions based on the provided knowledge base documents, focusing on the mass spectrometer and relative atomic mass (Ar) calculations: Questions 1. What is the "m/z" value in mass spectrometry an abbreviation for? * (A) Mass * (B) Mass to size ratio * (C) Mass to charge ratio * (D) Charge 2. In a mass spectrum, what does the height of a peak generally represent? * (A) The mass of the ion * (B) The charge of the ion * (C) The relative abundance of the ion * (D) The speed of the ion 3. Which species would cause a peak at m/z = 28 in a mass spectrum of silicon? * (A) 28Si * (B) 28Si2+ * (C) 28Si+ * (D) 28Si- 4. A sample of element X contains two isotopes: 63X (69.2% abundance) and 65X (30.8% abundance). What is the approximate Ar of element X? * (A) 63.0 * (B) 63.6 * (C) 64.0 * (D) 65.0 5. The Ar value tends to be given to how many decimal places? * (A) 0 * (B) 1 * (C) 2 * (D) 3 6. Chlorine has two main isotopes, 35Cl and 37Cl. In a mass spectrum of chlorine gas (Cl2), what is the m/z value of the peak corresponding to the (35Cl-37Cl)+ ion? * (A) 35 * (B) 37 * (C) 70 * (D) 72 7. In a mass spectrum of Cl2, the ratio of peaks for (35Cl-35Cl)+, (35Cl-37Cl)+, and (37Cl-37Cl)+ is: * (A) 1:1:1 * (B) 3:2:1 * (C) 9:6:1 * (D) 6:9:1 8. Bromine has two isotopes, 79Br and 81Br, in approximately a 1:1 ratio. Which molecular ion peak pattern would you expect in a mass spectrum of Br2? * (A) One peak * (B) Two peaks of equal height * (C) Three peaks in a 1:2:1 ratio * (D) Three peaks in a 1:1:1 ratio 9. If the abundance of isotopes is given as relative values and *not* percentages, what should you divide by when calculating Ar? * (A) 100 * (B) The sum total of the abundances * (C) The largest abundance value * (D) 1 10. True or false, isotopic masses are always whole numbers. * (A) True * (B) False 11. Element Z has two isotopes. Z-120 has a relative abundance of 60. Z-x has a relative abundance of 40. The Ar of element Z is 121.2, nd x. * (A) 120 * (B) 121 * (C) 122 fi *(D) 123 12. Which of the following is NOT a stage in mass spectrometry? * (A) Ionisation * (B) Acceleration * (C) Condensation * (D) Detection 13. During the ionisation stage... * (A) the sample is dissolved in a volatile solvent * (B) the sample is vaporised and bombarded with high energy electrons. * (C) the sample is passed through a magnetic eld. * (D) the sample is detected. 14. During the acceleration stage... * (A) the sample is passed through a magnetic eld. * (B) the positive ions are attracted to negatively charged plates. *(C) a detector measures the current. *(D) the ions are made. 15. During the de ection stage... * (A) ions are separated based on their mass to charge ratio. * (B) ions are separated based on their charge. * (C) ions are detected. * (D) ions are accelerated. 16. During the detection stage... * (A) The abundance of each ion is recorded. * (B) The ions are de ected. * (C) The sample is ionised. * (D) The ions are accelerated. 17. A sample of boron contains 20% 10B and 80% 11B. What is the relative atomic mass of boron in this sample? * (A) 10.5 * (B) 10.8 * (C) 10.2 * (D) 10.6 fl fl fi fi 18. If a molecule fragments in a mass spectrometer, the fragments detected will always be... * (A) Neutral molecules * (B) Positively charged ions * (C) Negatively charged ions * (D) Atoms 19. True or False: In a mass spectrum of a diatomic molecule, peaks corresponding to individual atoms are never observed, only molecular ions. * (A) True * (B) False 20. Magnesium contains 3 isotopes. 24Mg = 78.99%, 25Mg = 10.00%. If the relative atomic mass is 24.31, nd the percentage abundance of 26Mg. * (A) 21.01% * (B) 11.01% * (C) 10.00% * (D) 13.01% fi