The structures of graphite and boron nitride are shown below. [Figure B7.1: Diagram showing the layered structures of graphite and boron nitride. Key for graphite: • = carbon atom. Key for boron nitride: • nitrogen atom, O boron atom.]

1. (a)Like graphite, boron nitride feels slippery to the touch. Explain, in terms of structure and bonding, why boron nitride feels slippery to the touch.[2]
2. (b)An isotope of boron is represented by the symbol 11B. 5 Deduce the number of protons and neutrons in this isotope of boron. number of protons number of neutrons[1]
3. (c)Explain why graphite has a high melting point.[2]
4. (d)(i)Dilute sulfuric acid can be electrolysed using graphite electrodes. [Figure B7.2: Diagram showing an electrolysis setup with two graphite electrodes immersed in dilute sulfuric acid. Oxygen gas collects at the positive electrode (anode) and hydrogen gas at the negative electrode (cathode).] Graphite is a good electrical conductor. Explain why graphite conducts electricity.[1]
5. (d)(ii)Give another property of graphite that makes it useful as an electrode in this electrolysis.[1]
6. (e)(i)During the electrolysis of dilute sulfuric acid, oxygen is released at the anode (positive electrode) and hydrogen is released at the cathode (negative electrode). Complete the equation for the reaction at the anode. 4OH- → O₂ + ..... + .....[1]
7. (e)(ii)Construct the equation for the reaction at the cathode.[1]
8. (e)(iii)Explain why the volume of hydrogen produced is approximately double that of the oxygen.[1]

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