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In the complex salt [E(en)2(C2O4)]NO2, where en denotes ethylenediamine, what are the coordination number and oxidation state of element E, respectively?

1. 6 and 2
2. 4 and 2
3. 4 and 3
4. 6 and 3

Correct answer: 6 and 3

Solution

The coordination number of 6 indicates that element E is surrounded by six donor atoms from the ligands, which include two ethylenediamine (en) molecules and one oxalate (C2O4) ion. The oxidation state of 3 for element E is determined by balancing the overall charge of the complex with the charges contributed by the ligands and the nitrate counterion.

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