[MnCl₄]²⁻ is a complex ion.

1. (a)(i)Deduce the oxidation state of manganese in [MnCl₄]²⁻.[1]
2. (a)(ii)The [MnCl₄]²⁻ complex does not contain any 180° bond angles. Draw a three-dimensional diagram to show the shape of the [MnCl₄]²⁻ complex. State one bond angle on your diagram.[2]
3. (b)(i)A solution of cobalt(II) sulfate contains the complex ion [Co(H₂O)₆]²⁺. A solution containing [Co(H₂O)₆]²⁺ is reacted separately with an excess of each of NaOH(aq), NH₃(aq) and NaCl(aq). Write an equation for each of these reactions. State one observation that can be made immediately after the reaction, include the colour and state of the cobalt-containing product. [Co(H₂O)₆]²⁺ and an excess of NaOH(aq) equation observation[2]
4. (b)(ii)[Co(H₂O)₆]²⁺ and an excess of NH₃(aq) equation observation[2]
5. (b)(iii)[Co(H₂O)₆]²⁺ and an excess of NaCl(aq) equation observation[2]
6. (b)(iv)Name the type of reaction that occurs in (b)(iii).[1]
7. (c)(i)Cobalt forms the complex ion [Co(NH₃)₂(en)₂]²⁺. The abbreviation en is used for the bidentate ligand 1,2-diaminoethane, H₂NCH₂CH₂NH₂. The complex ion shows both geometrical and optical isomerism. Define the term bidentate ligand.[2]
8. (c)(ii)Draw three-dimensional diagrams for the two optical isomers of [Co(NH₃)₂(en)₂]²⁺. Each en ligand can be represented using N N[2]

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