Manganese, chromium and ruthenium are all transition elements.

1. (a)Explain what is meant by a transition element. [1][1]
2. (b)(i)Describe the colour change seen when an excess of Sn²⁺(aq) is added separately to • dilute acidified MnO₄⁻(aq) from .................................................... to .................................................... • dilute acidified Cr₂O₇²⁻(aq). from .................................................... to .................................................... [1][1]
3. (b)(ii)Write an equation for the reaction between Sn²⁺(aq) and acidified Cr₂O₇²⁻(aq). [1][1]
4. (c)(i)State what is meant by a co-ordination number of six. [1][1]
5. (c)(ii)State the formula of X. Include its charge. [1][1]
6. (c)(iii)Draw the two isomeric forms of X in the boxes below. Your diagrams should show • the three-dimensional shapes of the two isomers • how each ligand is attached to the central ruthenium ion. [3][3]
7. (c)(iv)Suggest the type of isomerism shown by X. [1][1]
8. (c)(v)Explain the origin of colour in a transition element complex such as X. [3][3]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.