2.3 Past Paper Questions

IB Chemistry – SL

Topic 2 Questions

1. Consider the composition of the species W, X, Y and Z below. Which species is an anion?

A. W

B. X

C. Y

D. Z

(Total 1 mark)

2. Energy levels for an electron in a Hydrogen atom are

A. evenly spaced.

B. farther apart near the nucleus.

C. closer together near the nucleus.

D. arranged randomly.

(Total 1 mark)

3. Which is related to the number of electrons in the outer main energy level of the elements from the alkali metals to the halogens?

I. Group number

II. Period number

A. I only

B. II only

C. Both I and II

D. Neither I nor II

(Total 1 mark)

7. What is the correct number of each particle in a fluoride ion, ₁₉F^–?

(Total 1 mark)

8. Which statement is correct for the emission spectrum of the hydrogen atom?

A. The lines converge at lower energies.

B. The lines are produced when electrons move from lower to higher energy levels.

C. The lines in the visible region involve electron transitions into the energy level closest to the nucleus.

D. The line corresponding to the greatest emission of energy is in the ultraviolet region.

12. How many valence electrons are present in an atom of an element with atomic number 16?

A. 2

B. 4

C. 6

D. 8

(Total 1 mark)

13. A certain sample of element Z contains 60% of ₆₉Z and 40% of ₇₁Z. What is the relative atomic mass of element Z in this sample?

A. 69.2

B. 69.8

C. 70.0

D. 70.2

(Total 1 mark)

14. What is the difference between two neutral atoms represented by the symbols ⁵⁹₂₇Co and ²⁸Ni?

A. The number of neutrons only.

B. The number of protons and electrons only.

C. The number of protons and neutrons only.

D. The number of protons, neutrons and electrons.

(Total 1 mark)

15. How many electrons are there in one ²⁴₁₂Mg²⁺ ion?

A. 10

B. 12

C. 14

D. 22

(Total 1 mark)

16. The electron arrangement of sodium is 2.8.1. How many occupied main electron energy levels are there in an atom of sodium?

A. 1

B. 3

C. 10

D. 11

(Total 1 mark)

17. Information is given about four different atoms:

Which two atoms are isotopes?

A. W and Y

B. W and Z

C. X and Z

D. X and Y

(Total 1 mark)

18. Which statement is correct about a line emission spectrum?

A. Electrons absorb energy as they move from low to high energy levels.

B. Electrons absorb energy as they move from high to low energy levels.

C. Electrons release energy as they move from low to high energy levels.

D. Electrons release energy as they move from high to low energy levels.

(Total 1 mark)

19. How many neutrons are there in the ion ₁₈O^2–?

A. 8

B. 10

C. 16

D. 20

(Total 1 mark)

20. What is the electron arrangement of Silicon?

A. 2.4

B. 2.8

C. 2.8.4

D. 2.8.8

(Total 1 mark)

21. Which statement is correct about the isotopes of an element?

A. They have the same mass number

B. They have the same electron arrangement

C. They have more protons than neutrons

D. They have the same numbers of protons and neutrons

(Total 1 mark)

22. What’s the difference between 2 atoms represented by the symbols ²¹⁰₈₄Po and ²¹⁰₈₅At?

A. The number of neutrons only.

B. The number of protons and electrons only.

C. The number of protons and neutrons only.

D. The number of protons, neutrons and electrons.

(Total 1 mark)

23. Which statements are correct for the emission spectrum of the Hydrogen atom?

I. The lines converge at lower energies.

II. Electron transition to n =1 are responsible for lines in the UV region.

III. Lines are produced when electrons move from higher to lower energy levels.

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

(Total 1 mark)

24. What is the symbol for a species that contains 15 protons, 16 neutrons and 18 electrons?

A. ³¹ ₁₆S

B. ³¹ ₁₆S^3-

C. ³¹ ₁₅P

D. ³¹ ₁₅P^3-

(Total 1 mark)

25. What is the electron arrangement of an Al³⁺ ion?

A. 2, 8

B. 2, 3

C. 2, 8, 3

D. 2, 8, 8

(Total 1 mark)

26. What will happen to the volume of a fixed mass of gas if the pressure and the Kelvin temperature are both doubled?

A. It will remain the same.

B. It will be double its initial volume.

C. It will be one-half its initial volume.

D. It will be four times its initial volume.

(Total 1 mark)

27. Which species has 54 electrons and 52 protons?

A. ¹²⁸ ₅₂ Te^2-

B. ¹³² ₅₄ Xe²⁺

C. ¹³² ₅₄ Xe^2-

D. ¹²⁸ ₅₂ Te²⁺

(Total 1 mark)

28. What is the correct sequence for the processes occurring in a mass spectrometer?

A. vaporization, ionization, acceleration, deflection

B. vaporization, acceleration, ionization, deflection

C. ionization, vaporization, acceleration, deflection

D. ionization, vaporization, deflection, acceleration

(Total 1 mark)

30. State the number of protons, electrons and neutrons in the ion ¹⁵ ₇N^3–.

…………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………(Total 2 marks)

31. A sample of germanium is analysed in a mass spectrometer. The first and last processes in mass spectrometry are vaporization and detection.

(a) (i) State the names of the other three processes in the order in which they occur in a mass spectrometer.

.........................................................................................................................

......................................................................................................................(2)

(ii) For each of the processes named in (a) (i), outline how the process occurs.

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......................................................................................................................(3)

(b) The sample of Germanium is found to have the following composition:

(i) Define the term relative atomic mass.

.........................................................................................................................

(2)

(ii) Calculate the relative atomic mass of this sample of Germanium, giving your answer to two decimal places.

.........................................................................................................................

(2)

(Total 9 marks)

32. Define the following terms.

(i) atomic number

....................................................................................................................................

(1)

(ii) mass number

....................................................................................................................................

(1)

(Total 2 marks)

33. State the electron arrangements of the following species:

Si ........................................................................................................................................

P^3– ........................................................................................................................................

(Total 2 marks)

34. Identify the numbers of protons, neutrons and electrons in the species ₃₃S^2–.

..............................................................................................................................................

(Total 1 mark)

35. State the electron arrangement for atoms of Aluminium, Nitrogen and Fluorine.

(Total 2 marks)

36. The relative atomic mass of Chlorine is 35.45. Calculate the percentage abundance of the two isotopes of Chlorine, ₃₅Cl and ₃₇Cl in a sample of chlorine gas.

(Total 2 marks)

37. (a) Describe the following stages in the operation of the mass spectrometer.

(i) ionization

(2)

(ii) deflection

(2)

(iii) acceleration

(1)

(b) (i) State the meaning of the term isotopes of an element.

(1)

(ii) Calculate the percentage abundance of the two isotopes of Rubidium ₈₅Rb and ₈₇Rb.

(2)

(iii) State two physical properties that would differ for each of the rubidium isotopes.

(1)

(iv) Determine the full electron configuration of an atom of Si, an Fe³⁺ ion and a P^3– ion.

(3)

(Total 12 marks)

38. Naturally occurring copper has a relative atomic mass, (A_r), of 63.55 and consists of two isotopes ₆₃Cu and ₆₅Cu.

(i) Define the term relative atomic mass, A_r.

....................................................................................................................................

(1)

(ii) State and explain which is the more abundant isotope.

....................................................................................................................................

(1)

(Total 2 marks)

39. The element vanadium has two isotopes, ⁵⁰ ₂₃V and ⁵¹ ₂₃V and a relative atomic mass of 50.94.

(a) Define the term isotope.

……………………………………………………………………………………….

(1)

(b) State the number of protons, electrons and neutrons in ⁵⁰ ₂₃V

……………………………………………………………………………………….

(2)

(c) State and explain which is the more abundant isotope.

……………………………………………………………………………………….

(1)

(d) State the name and the mass number of the isotope relative to which all atomic masses are measured.

……………………………………………………………………………………….

(1)

(Total 5 marks)

40. (a) State a physical property that is different for isotopes of an element.

.....................................................................................................................................

(1)

(b) Chlorine exists as two isotopes, ₃₅Cl and ₃₇Cl. The relative atomic mass of Chlorine is 35.45. Calculate the percentage abundance of each isotope.

.....................................................................................................................................

(2)

(Total 3 marks)

41. (a) Define the term isotope.

.....................................................................................................................................

(2)

(b) A sample of Argon exists as a mixture of three isotopes.

mass number 36, relative abundance 0.337%

mass number 38, relative abundance 0.0630%

mass number 40, relative abundance 99.6%

Calculate the relative atomic mass of Argon.

.....................................................................................................................................

(2)

(c) State the number of electrons, protons and neutrons in the ion ₅₆Fe³⁺.

electrons: ............................ protons: ............................. neutrons: ...........................

(2)

(Total 6 marks)

42. The element Bromine exists as the isotopes ₇₉Br and ₈₁Br, and has a relative atomic mass of 79.90.

(a) Complete the following table to show the numbers of sub-atomic particles in the species shown.

(3)

(b) State and explain which of the two isotopes 79Br and 81Br is more common in the element bromine.

...................................................................................................................................

(1)

(c) The element Calcium is in the same period of the Periodic Table as Bromine.

(i) Write the electron arrangement for an atom of Calcium.

.........................................................................................................................

(1)

(ii) Deduce the formula of the compound Calcium Bromide.

.........................................................................................................................

(1)

(Total 6 marks)

43. Some vaporized magnesium is introduced into a mass spectrometer. One of the ions that reaches the detector is ₂₅Mg⁺.

(a) Identify the number of protons, neutrons and electrons in the ₂₅Mg⁺ ion.

....................................................................................................................................

(1)

(b) State how this ion is accelerated in the mass spectrometer.

....................................................................................................................................

(1)

(c) The ₂₅Mg²⁺ ion is also detected in this mass spectrometer by changing the magnetic field. Deduce and explain, by reference to the m/z values of these two ions of magnesium, which of the ions ₂₅Mg²⁺ and₂₅Mg⁺ is detected using a stronger magnetic field.

....................................................................................................................................

(2)

(Total 4 marks)

44. (a) List the following types of electromagnetic radiation in order of increasing wavelength (shortest first).

I. Yellow light

II. Red light

III. Infrared radiation

IV. Ultraviolet radiation

.....................................................................................................................................

(1)

(b) Distinguish between a continuous spectrum and a line spectrum.

.....................................................................................................................................

(1)

(c) The thinning of the ozone layer increases the amount of UV-B radiation that reaches the Earth’s surface.

Type of Radiation

UV-A

UV-B

Wavelength / nm

320–380

290–320

Based on the information in the table above explain why UV-B rays are more dangerous than UV-A.

.....................................................................................................................................

(3)

(Total 5 marks)