The major problem of the Nigerian federal structure in the first republic was

The major problem of the Nigerian federal structure in the first republic was ethnicity. The country was made up of diverse ethnic groups with different cultures, traditions, and languages. This led to ethnic tensions and conflicts, especially in the areas of political representation and distribution of resources. The competition for power and resources among the various ethnic groups often resulted in violence and instability, and this greatly undermined the effectiveness of the federal system. As a result, many people believed that the federal structure was incapable of managing Nigeria's diversity, and this contributed to the military coups and instability that characterized the first republic.