Transition Elements

The magnetic moments of the ions are related to the number of unpaired electrons in their electronic configuration. The given magnetic moments and electronic configurations for the ions are:

• (A) has a magnetic moment of 3.87 BM (which corresponds to 3 unpaired electrons).
• (B) has a magnetic moment of 5.92 BM (which corresponds to 5 unpaired electrons).
• (C) has a magnetic moment of 4.90 BM (which corresponds to 4 unpaired electrons).
• (D) has a magnetic moment of 1.73 BM (which corresponds to 1 unpaired electron).

Step 1: Coordination Numbers of Transition Elements.
Transition metals, especially in the second and third periods, commonly form complexes with high coordination numbers due to their relatively large size and ability to accommodate multiple ligands. Hence, they do not typically show low coordination numbers.

Step 2: Analyzing the Options.
- (1) The statement "The metals commonly show lower coordination number" is not true for the second and third row transition metals. They tend to have higher coordination numbers. - (2) Binuclear carboxylate complexes are common for transition metals. - (3) Many halides of transition elements are indeed cluster compounds, especially in higher oxidation states. - (4) Transition metals can form carbonyl complexes with metal-metal bonds, such as in dicobalt octacarbonyl.

Step 3: Conclusion.
Thus, the incorrect statement is (1), so the correct answer is option (1).