Which is the last step in amending the u.S. Constitution?

No, the Tenth Amendment is the last Amendment in the Bill of Rights (the first Ten Amendments to the Constitution). As of 2011, the US Constitution has 27 Amendments; the last, concerning compensation to members of Congress, was ratified in 1992.

Explanation:

The impact of adding a free or slave state would result in an imbalance of free and slave states in Congress.

Every state that is added to the US gets representation in both the House of Representatives and the Senate. Each state gets two representatives in the Senate and a number of representatives in the House based on the states population. Having members in the Senate and House of Representatives is extremely important, as these parts of the legislative branch make laws for the entire country to follow.

With this in mind, an imbalance of free and slave states could cause a problem. This is because free states are worried that if more slave states are added, they will try to create a law that makes slavery legal everywhere. On the other hand, slave states are worried that if free states gain too much power in Congress, they will make a law outlawing slavery in the US. This scenario helps to explain why the US faced so many problems during the early to middle part of the 19th century.