Final answer:
The Senate holds impeachment trials and makes decisions about treaties.
Step-by-step explanation:
The body that holds impeachment trials and makes decisions about treaties is the Senate. The House of Representatives has the power to impeach federal officials, but the Senate conducts the actual trial and makes the final decision on whether to remove the official from office. The Senate also has the authority to ratify treaties negotiated by the President.
Learn more about structure of government