Final answer:
The necessary and proper clause has expanded federal authority, not limited it. Jefferson's economic pressure tactics were not effective against Britain and France. The Iroquois Confederacy did not maintain complete neutrality during the Revolutionary War.
Step-by-step explanation:
The statement that the necessary and proper clause has had the effect of limiting the power of the national government is False. The necessary and proper clause, also referred to as the elastic clause, has actually enabled Congress to enact laws that are deemed necessary and proper for carrying out its powers, thereby broadening the scope of federal authority over time.
Also, the assertion that Jefferson's efforts to use economic pressure to solve the situation with Britain and France were successful is False. Jefferson's efforts, particularly the Embargo Act of 1807, generally had a negative impact on the American economy and were not successful in changing the policies of Britain and France.
When addressing whether all tribes in the Iroquois Confederacy maintained neutrality during the Revolutionary War, the statement is False. While some members of the Iroquois Confederacy sought to remain neutral, the Confederacy itself was split, and different tribes ultimately took sides in the conflict.