American leaders sought to draft the constitution as a new plan of government. what had the previous plan failed?

The Articles of Confederation.

The Articles of Confederation failed for one simple reason; weakness. The first "constitution" failed was due to the following reasons:

Eventually, all these reasons created a very difficult and poorly designed government. Shay's Rebellion in 1786-1787 ultimately marked the end of the Articles Of Confederation, as it showed how weak the central government truly was. The U.S. could not protect a perpetual union, and Founders of the AOC pushed to create an entirely new and more effective document to lay the law of the land. And so, the U.S. Constitution was born in 1787, and it continues to be a flexible document to this day.

1.the population change is near or at replacement level.

4. the birth and death rates are balanced.

6. sweden is most likely a developed country.

the conditions that made the byzantine empire vulnerable to attacks by the muslin turks were the sack of constantinople by western crusaders, the conquests of the sultanate of rum, presence of rival kingdoms and finally the set up of fiefdoms at the empire which were owned by the ghazis (turkish warriors).