1. 1
   A lighting engineer designs advertising signs that glow with different colours when an electric current passes through tubes filled with different noble gases, such as neon and argon.

   (a)

   Why are noble gases such as neon suitable for use in gas discharge tubes without reacting with the tube or other gases?

   [1 mark]

   • AThey have a full outer shell of electrons
   • BThey have one electron in their outer shell
   • CThey readily form ions
   • DThey are highly reactive metals

   (b)

   How is the atomic structure of noble gases best described?

   [1 mark]

   • ADiatomic molecules
   • BMonatomic gases
   • CGiant ionic lattices
   • DGiant covalent structures

   (c)

   State two general properties of noble gases (Group VIII) illustrated by their use in lighting.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A diving equipment manufacturer investigates using helium mixed with oxygen in breathing gas for deep-sea divers, instead of nitrogen, because helium does not react with other substances in the body under pressure.

   (a)

   Helium is in Group VIII (0) of the Periodic Table. How many electrons does a helium atom have in its outer shell?

   [1 mark]

   • A8
   • B4
   • C1
   • D2

   (b)

   Why is helium chosen instead of nitrogen for deep-sea diving gas mixtures, in terms of reactivity?

   [1 mark]

   • AHelium has an incomplete outer shell so bonds easily
   • BHelium is a Group I metal
   • CHelium has a full outer shell of electrons so does not react with other substances
   • DHelium readily forms compounds under pressure

   (c)

   Explain, in terms of electronic configuration, why helium and other noble gases are unreactive.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student studies the Periodic Table and notices a pattern: argon is in Period 3 and Group VIII (0), while krypton is in Period 4 and Group VIII (0).

   (a)

   Explain how the group number of an element in Groups I to VII is related to the number of electrons in its outer shell, and describe how the noble gases fit this pattern.

   [3 marks]

   (b)

   Argon is in Period 3 and krypton is in Period 4. Explain what the period number tells you about the electronic structure of these atoms, and state the number of occupied electron shells in an atom of krypton.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A materials scientist investigates why certain gases are used to fill welding equipment and protect metals from reacting with the surrounding air during high-temperature processes.

   (a)

   Explain, using ideas about electronic configuration, why noble gases are unreactive monatomic gases, and describe how this property relates to their position in the Periodic Table.

   [6 marks]

   (b)

   Explain why noble gases are suitable for protecting hot metals from reacting with air during welding, and describe how the number of occupied electron shells changes as you move down Group VIII from helium to krypton.

   [6 marks]

   Total for question 4: 12 marks

End of questions