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The coordination numbers of Co and Al in [CoCl(en)2]Cl and K3[Al(C2O4)3], respectively, are: (en = ethane-1,2-diamine) (1) 3 and 3 (2) 6 and 6 (3) 5 and 3 (4) 5 and 6

1. 3 and 3
2. 6 and 6
3. 5 and 3
4. 5 and 6

Correct answer: 6 and 6

Solution

In [CoCl(en)2]Cl, cobalt is coordinated by two bidentate ethylenediamine (en) ligands and one chloride ion, resulting in a coordination number of 6. In K3[Al(C2O4)3], aluminum is surrounded by three bidentate oxalate (C2O4) ligands, also giving it a coordination number of 6.

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