The principal powers of Congress include all except

the power of the purse.
the power to declare war.
implied powers.
x the power to hire generals.

correct

To determine the correct answer to this question, we need to examine the role and powers of Congress.

The power of the purse is a term used to describe the power of Congress to control and allocate government spending. This includes the ability to collect taxes, create a budget, and appropriate funds for various government programs and activities. Therefore, the power of the purse is indeed one of the principal powers of Congress.

The power to declare war is also a significant power held by Congress. According to the United States Constitution, only Congress has the authority to declare war. This power ensures that decisions regarding military conflicts are made collectively by elected representatives rather than being concentrated solely in the hands of the executive branch.

Implied powers are another important aspect of Congress's authority. Implied powers refer to powers that are not explicitly stated in the Constitution but are necessary and proper to carry out its enumerated powers. These powers are derived from the Necessary and Proper Clause (also known as the Elastic Clause) found in Article I, Section 8 of the Constitution. Implied powers give Congress the flexibility to create laws and regulations that are necessary to carry out its duties effectively.

The power to hire generals, however, is not one of the principal powers of Congress. The task of appointing and hiring military officers, including generals, falls under the authority of the President as the Commander-in-Chief of the armed forces.

Therefore, the correct answer is "the power to hire generals" as it is not one of the principal powers of Congress.